Organic compounds of sulphur, selenium, and tellurium vol 3

Barrett 1 Textbooks and Reviews 2 Spectroscopic and Other Properties Photoelectron Spectra Dipole Moments Nuclear Magnetic Resonance Spectra Ultraviolet and Circular Dichroism Spectra

A Specialist Periodical Report

G C Barrstt, Oxford Polytechnic

R J S Beer, University of Liverpool

D C Dittmer, Syracuse University, New York, U.S.A

1 Durst, University of Ottawa, Ontario, Canada

F Duus, Odense University, Denmark

J Fabian, Sektion Chemie der Technischen Universitat, Dresden,

J G Gleason, Smith Kline and French Laboratories, Philadelphia,

S Gronowitz, University of Lund, Sweden

A W Johnson, University of North Dakota, U.S.A

F Kuner, Royal free Hospital School of Medicine, London

G Prota, Universita di Napoli, Italy

E Germany

Pennsylvania, U.S.A

The Chemical Society

ISBN: 0 85186 279 9

ISSN : 0305-98 1 2

Library of Congress Catalog Card No 77-23818

Filmset in Northern Ireland at The Universities Press, Belfast Printed by photolithography and bound in Great Britain at The Pitman Press, Bath

Preface

The general aims and structure of this third Volume of ‘Organic Compounds

of Sulphur, Selenium, and Tellurium’ remain those set out in the Preface to Volume 1

In accordance with intention expressed in the Preface to Volume 1 to give more detailed treatment to unusually important or topical subjects, a new chapter is introduced in this volume entitled ‘f3 -Lactam Antibiotics, Other Sulphur-containing Natural Products, and Related Compounds’

‘Theore tical Aspects of Organosulphur and Organoselenium Compounds’

is a review for the period April 1970 to March 1974, with emphasis in this volume on conjugated systems A review of the chemistry of Thiepins, Dithiins, and Thiazepines has been omitted A review of these subjects,

covering the four-year period April 1972 to March 1976, will appear in Volume 4 Reviewing of all other material covered in this Volume is for the two-year period April 1972 to March 1974

D H R

dime thy1 sulp hoxide

electron spectroscopy for chemical analysis electron spin resonance

Contents

Compounds, Compounds with Exocyclic Sulphur Functional Groups, and their Selenium and Tellurium Analogues

B y G C Barrett

1 Textbooks and Reviews

2 Spectroscopic and Other Properties

Photoelectron Spectra Dipole Moments Nuclear Magnetic Resonance Spectra Ultraviolet and Circular Dichroism Spectra Infrared Spectra

Mass Spectra Electron Spin Resonance Spectra Other Physical Studies

3 Thiols

Preparations Thiols as Nucleophiles Addition Reaction of Thiols Generation and Reactions of Thiyl Radicals React ions of T hiols with Organophosphorus Protection of -SH Groups

Thiols in Biochemistry Thiolacids and Thiolesters Compounds

4 Sulphides

Preparations Saturated Aliphatic Sulphides; Aryl Sulphides Unsaturated Sulphides

Reactions of Sulphides with Carbenes and Nitrenes; a-Thiocarbenes

Thiocyclopropenium Cations Sulphides in Synthesis

viii

Sulphides as Reagents Hete r oar y 1 Sulp hide s

Sulphides Related to Natural Products Sulphuranes

Thloacetals and Related Compounds

Preparations Reactions

Sulphoxides

Preparations Properties and Reactions of Sulphoxides a-Sulphinyl Carbanions

&-Halogenated Sulphoxides p-Keto-sulphoxides and Related Compounds Unsaturated Sulphoxides

Sulphoxides and Selenoxides in Alkene Applications of Dimethyl Sulphoxide and Synthesis

other Sulp hoxide s as Oxidants Sulphimides and Sulphoximides

Sulphimides Sulphoximides

Sulphones

Preparations Reduction of Sulphones Cleavage and Rearrangement of Sulphones Ring Substitution of Aryl Sulphones a-Halogenosulphones

Other a-Functional Sulphones P-Keto-sulphones

a-Sulphonyl Carbanions Bis(sulphony1)methanes Unsaturated Sulphones Sulphones in Synthesis

Sulphenic Acids

Preparations Reactions of Sulphenic Acids

Sulphenates Sulphenyl Halides Subhenamides

Contents

10 Thiocyanates and Isothiocyanates

Preparations of Thiocyanates

Properties of Thiocyanates Preparations of Isothiocyanates Reactions of Isothiocyanates

11 Sulphinic Acids

Preparations Reactions of Sulphinic Acids

Sulphinate Esters Sulphinyl Halides Sulphinamides

12 Sulphonic Acids

Preparation Sulphonates Sulphonyl Peroxides Sulphonyl Halides and Sulphenes Sulp honamide s

Sulphonyl Cyanides and Isocyanates Sulphonyl Azides

13 Disulphides, Polysulphides, and their

Thiiran 1-Oxides

Formation Intermediates in Reactions Chemical and Physical Properties

Thiiren Derivatives

Theoretical Considerations Intermediates in Reactions Chemical Properties

and One or Two other Heteroatoms 112

Thietans

Physical Properties Formation

Intermediates in Reactions Chemical Properties

Rings containing Two Nitrogen Atoms 129

Four-membered Rings containing Oxygen and

One Sulphur Atom

Sultones and Sultines (1,2-Oxathietan Oxathietans, Oxathiets, and Dioxathietans 2,2-Dioxides and 1,2-0xathietan 1-Oxides)

1,2-Dithietans and 1,3-Dithietans

Synthesis Reactions and Properties

in the Ring and their Oxy-sulphur Analogues

Cyclic Disulphides 1,3-Dithiolans and 1,3-Dithians Synthesis

React ions 1,5-Dithiocans 1,4-Dithians, 1,4-Dithiepans, and

Compounds containing Three or More Sulphur Atoms

1,2,4-Trithiolans, 1,3,5-Trithians, and 1,2,4,5Tetrathians

Large Ring Disulphides, including Sulphur-containing Cyclophanes

Compounds containing Sulphur o r Selenium and Oxygen

Sultines, Sultones, and Related Systems 1,3-Oxathiolans, 1,3-0xathians,

1,4-Oxathians, and Related Compounds Cyclic Sulphites and Related Compounds

xii Contents

Su I p hu r-contai ni ng Natural Products, and Related Compounds

B y J G Gleason

1 Introduction

2 Fermentation and Biosynthetic Aspects

3 Modification of the @-Lactam Ring System

Modification at C-6(7)

Epimerization Modifications in the Thiazine Ring

4 Partial Synthesis of Cephalosporins

8 Other Sulphur-containing Natural Products

Chapter 5 Thiocarbonyl and Selenocarbonyl

3 Thioketones and Selenoketones

Synthesis Transient Species Metal Complexes Reactions

4 Thioketens and Selenoketens

5 Thiocarbonyl Ylides, Thiocarbonyl SImides,

and their Selenium Analogues

Thioureas and Selenoureas

Synthesis Reactions

Thiosemicarbazides and Selenosemicarbazides

Synthesis Reactions

Thionocarboxylic and Dithiocarboxylic Acids,

their Derivatives, and the Selenium Analogues

Synthesis Reactions

Thionocarbonates, Thionodithiocarbonates,

Trithiocarbonates, and their Selenium Analogues

Synthesis Reactions

Thionocarbamic and Dithiocarbamic Acids,

their Derivatives, and their Selenium Analogues

Synthesis Reactions

Physical Properties

Structure Tautomerism Hydrogen Bonding Polarization Effects, Restricted Rotation, and Isomerization Phenomena

Crystal and Molecular Structures Ultraviolet Spectra

Infrared and Raman Spectra Rotational Spectra

N.M.R Spectra E.S.R Spectra Photoelectron and ESCA Spectra Mass Spectra

xiv Contents

Other Physical Properties 320

Acidity and Basicity Measurements 321

Chapter 6 Ylides of Sulphur, Selenium, and

Tellurium, and Related

Contents

4 Thieno[3,4-c]thiophens and Related Compounds

Thieno[ 3,4-c] thiophens Thieno[ 3,4- c]f uran s

Thieno[3,4-~]pyrroles Thieno[3,4-c]pyrazoles

5 Miscellaneous Ring Systems

Chapter 8 Thiophens and their Selenium and

Electronic Spectra 1.r Spectra Dipole Moments N.M.R Spectra Various Physical Properties Electrophilic Substitution Electrophilic Ring-closure Radical Reactions Nucleophilic Substitutions Metallation and Halogen-Metal Exchange Photochemistry of Thiophens

Electrochemical Reactions The Structure and Reactions of Hydroxy- and Mercapto-thiophens

Aminothiophens and their Reactions Side-chain Reactivities

Chloromethyl Derivatives Reactions of Thiophen Aldehydes and Various Side-chain Reactions

Bi- and Poly-heterocycles Thiophen Analogues of Porphyrins Reactions Leading to Destruction of the Naturally occurring Thiophens

Thiophens of Pharmacological Interest

xvi Contents

3 Thienothiophens, their Benzo-derivatives,

and Analogous Compounds

Synthesis Theoretical Studies and Physical Properties Substitution Reactions

Non-classical Thienothiophens

4 Benzothiophens and their Benzo-fused Systems

Synthesis of Benzothiophens by

Ring-closure Reactions Physical Properties Electrophilic Substitution Nucleophilic Substitution, Metallation, Side-chain Reactions

Photochemistry

2- and 3-Hydroxybenzo[b]thiophen Systems

Reaction at Sulphur Pharmacologically Active Compounds and Halogen-Metal Exchange

5 Thiophen Analogues of Polycyclic

Related Compounds Thiophens

7

Heterocyclic Rings

Thiophen Analogues of Quinoline

Thiophen Analogues of Isoquinoline Pyrimidine-fused Systems

Pyridazine-fused Systems Thiophens Fused with other Nitrogen- containing Heterocycles

Miscellaneous Fused Systems

Physical Properties Electrophilic Substitution Nucleophilic Substitution, Metallation, Side-chain Reactivities

Derivatives

and Halogen-Metal Exchange Benzo[ b]selenophens and their Benzo-fused Selenophens Fused to Five-membered Rings Selenophens Fused to Six-membered Tellurophens

Heterocyclic Aromatic Rings

6a-Th ia t h io p h t he n s a n d Re I at ed

B y R J S Beer Introduction

Compounds

Structural and Theoretical Studies Synthesis of 6a-Thiathiophthens Properties and Reactions of

I ,2-Dithiolylidene Aldehydes and Ketones 6a-Thiathiophthens

Multisulphur Systems 6a-Selenathiophthens Other Analogues of 6s-Thiathiophthen

Thiop yran 1,l-Dioxides Thiopyrylium Salts Thiochromans and Thiochromenes Thiochromones and Thiocoumarins Thioisochromans and Related Compounds Thioxanthenes, Thioxanthones, and

Complex Thiopyran Derivatives

From Oxathiazolones

From Meso-ionic 1,3,2-0xathiazolium-5-olates

From Isoxazoles From 1 ,ZDithiolans Condensation of Nitriles and Dialkyl Sulphites Photoisomerization of Thiazoles

From Thione-S-imides From p-Aminocrotonic Esters Type F Syntheses

Physical Properties Chemical Properties

Free-radical Reactions Alkylation and Quaternization Nitration

Nucleophilic Reactions Further Rearrangements

Contents

Complex Formation Biochemical

7 Naphthisothiazoles and Isothiazolanthrene

8 Other Condensed Ring Systems

incorporating Isothiazole Thieno[2,3-~]isothiazoles

Isothiazolopyridines Isothiazolo[4,3-d] thioisocoumarin

3 Physical Properties of Thiazoles

4 Chemical Properties of Thiazoles

Photolytic and Related Reactions Quaternization and Alkylation Acylation

Electrophilic Substitution Nucleophilic Substitution Ring Expansion to 1,4-Thiazines Dimerization

Ylides of Thiazolium Ions Deh y drothiazole

Miscellaneous Reactions Cyanine Dyes

Analytical Meso-ionic Thiazoles

Physical Properties of A’-Thiazolines Chemical Properties of A2-Thiazolines Synthesis of A4-Thiazolines

Properties of A4-Thiazolines Synthesis of Thiazolidines

Type A Syntheses Type B Syntheses Type D Syntheses Type E Syntheses Type G Syntheses

Properties of Thiazolidines

Spectra N- Alk ylation Ring Scission Condensations at the 5-Methylene Group Grignard Reagents

Penicillins Pep tides Biochemical and Physiological Properties Rhodanine, Isorhodanine, and Thiorhodanine

From o-Aminothiophenols Jacobson-Hugershoff Synthesis

Contents

Other Type B Syntheses Type C Syntheses

3 Physical Properties of Benzothiazoles

4 Chemical Properties of Benzothiazoles

Homolysis, Oxidation, and Reduction Nucleophilic Substitution

Nitration Organometallic Reagents Condensations

Rearrangement Ring Expansion to 1,4-Thiazines Polymethine and other Dyes Metal Complexes

Chemiluminescence and Bioluminescence Biochemical and Miscellaneous

Rings

Thiazolo[3,2-d] tetrazoles ThiazoIo-[2,3-c]- and -[3,2-b]-syrn-triazoles Imidazo[2,l-b] thiazoles

PyrroloC2, 1- b] thiazoles Thieno[2,3-d] thiazoles

6 Structures comprising One Five-membered

and One Six-membered Ring

Thiazolo[2,3-b] [ 1,3,5]thiadiazines

Thiazolo[3,2-a]-syrn-triazines

5 Structures comprising Two Five-membered

Meso-ionic Thiazolo[3,2,-a]-syrn- triazine-5,7-diones

Thiazolo[ 5,4-d]pyrimidines Thiazolo[ 3,2-a]pyridines

Thiazolo[4,5-b]pyridines

Thiazolo[5,4- blpyridines

7 Structures comprising Two Five-membered

and One Six-membered Ring

s yrn-Triazolo[3,4-b] benzothiazoles Thiazolo[ 3,2-e]purines

Thiazolo[4,5-flindazoles Imidazo[2,l-b]benzothiazoles

Pyrrolo[ 1,2-a]thiazol0[5,4-e]pyrimidines

Indolino[2,l-b] thiazoles

8 Structures comprising One Five-membered

and Two Six-membered Rings

Pyrido[3,2-d] thiazolo[ 3 ,2-a]pyrimidines Pyrimido[2,3-b] thiazolo[5,4-b]pyridines Pyrimido[2,l-b]benzothiazoles Thiazolo[4,5-c]cinnolines

Thiazolo [ 2,3 - b]quinazolines

Thiazolo[4,5-b]quinoxalines

Thiazolo[3 ,2-a]-quinolines (and -isoquinolines) Thiazolo[4,5-fl- and - [5,4-fl-quinolines

Thiazolo[2,3-a]isoquinoline

Thiazolo-[4,5-h]-, -[5,4-fl-, and -[5,4- h]-isoquinolines

9 Structures comprising Two Five-membered

and Two Six-membered Rings Pyrido[2,3-d]imidazo[2,l-b]thiazolo-

[5,4-b]pyridine and Related Systems

10 Structures comprising One Five-membered

and Three Six-membered Rings Thiazolo[4,5-b]phenothiazine

Pyrido[ 3,2-a] thiazolo [ 2,3- b]quinazolines Benzothiazolo- [2,3- b] - and

By Other Reactions

3 Properties of 1,2,3-Thiadiazoles

xxiv Contents

3 1,3-Thiazines

Simple 1,3-Thiazines Benzo- 1,3-thiazines

4 1,4-Thiazines

Monocyclic 1,4-Thiazines Benzo- 1,4-Thiazines and Related Compounds Phenothiazines (Dibenzo- 1,6thiazines) and Related Compounds

sulphur and Organoselenium Compounds

B y J Fabian

1 Introduction

2 Theoretical Methods

Semi-empirical Calculations Non-empirical Calculations

3 Aromaticity of Organosulphur Compounds

4 Cyclic n-Systems with Sulphur-containing Groups

Thiols and Sulphides Sulphonium Compounds, Sulphonic Acids, and Sulphones

Thiones

5 Heterocyclic Sulphur and Selenium Compounds

47r Heterocycles and Derivatives

67r Heterocycles and Derivatives Unsubstituted Thiophens Substituted Thiophens Annelated Thiophens Thiazoles, Isothiazoles, and Selenazoles Thiadiazoles and Selenathiadiazoles Thiopyrylium and Dithiolium Ions Thiopyrones, Dithiolones, and Derivatives Thiepins

Dithiins, Oxathiins, and Thiazines Heterocycles with more than Eight 7r Electrons Monocyclic Sulphur Compounds

Thiathiophthens and Oxygenated Derivatives

8n Heterocycles and Derivatives

Contents xxv

Cyclopentathiopyrans, Cyclopentadithiols, and Naphthothiopyrans 759

by a Polymethinic Chain 762 Sulphur Heterocyclic Radicals 764

Sulphur Heterocycles Bridged by a Single Sulphur Heterocycles Bridged by a Double Sulphur and Selenium Heterocycles Bridged

1

pounds with Exocyclic Sulphur Functional Groups, and their Selenium and Tellurium Analogues

BY G C BARRETT

The layout adopted in Volumes 1 and 2 of this Series is retained, though spectroscopic and other physical properties are given an integrated account (Section 2) this year This allows easier comparison to be made for the different sulphur-containing functional groups; it is also a device, one of several employed on this occasion, to save space, so that an ever-increasing volume of important work can be contained within a smaller number of

pages

1 Text-books and Reviews

Text-books and monographs include the reappearance of Suter’s book,’ and

a competitor with the same title,’ and others on ~ulphur,~ and on selenium‘ and tellurium’ compounds General reviews of developments in organo- sulphur chemistry: organo-selenium compounds,’ and organo-tellurium compounds’ are available, and more specialized reviews include: protection

‘The Organic Chemistry of Sulphur’, by C M Suter, Gordon and Breach, New York, 1971

* ‘The Organic Chemistry of Sulphur’, ed S Oae, Plenum Press, London, in the press (cited in

Tetrahedron Letters, 1973, 4751 and J.C.S Perkin I, 1973, 59)

’ ‘Chemistry and Biochemistry of the Sulphydryl Group in Amino-acids, Peptides and Proteins’,

by M Friedman, Pergamon, Oxford, 1973; ‘Sulphur Research Trends’, ACS Advances in Chemistry Series No 110, 1971; ‘The Determination of Sulphur-containing Groups’, by M R

F Ashworth, Vol 1, Academic Press, London, 1972; ‘The Analytical Chemistry of Sulphur and its Compounds’, ed J H Karchmer, Wiley-Interscience, New York, 1972

‘Organic Selenium Compounds’, ed D L Klayman and W H Gunther, Wiley-Interscience,

New York, 1973

D R Hogg, in MTP International Review of Science, Organic Chemistry Series One, Vol 2, p

259, 1973; L Field, Synthesis, 1972, 101

’ A Fredga, Kern Tidskr., 1972, 84, 26, 31

N Petragnani, Ann New York Acad Sci., 1972, 192, 10

’ ‘Tellurium’, ed W C Cooper, Van Nostrand, New York, 1971

1

2 Organic Compounds of Sulphur, Selenium, and Tellurium

of the -SH group: sulphur-centred radicals,” sulphuranes” and hyperva- lent Se and Te compounds,12 selenides of thiophen, furan, and selenophen,” (alkylthi~)acrylates,’~ sulphoxides (synthesis and reactions1sc and behaviour

in strong dimethyl sulphoxide with DCC11’*’8 or with P205’8 or Ac20I8 as an oxidant, sulphoximines in synthesis,Ia quadricovalent S as a chiral centre,’5b electronic effects of the sulphonyl g r o ~ p , ” ~ synthesis of aliphatic thiocyanates,” sulphinic a c i d P and sulphite sul- phenes,”“ sulphonyl isocyanates,Isf thi~lsulphinates,’~’ and Bunte saltsm

2 Spectroscopic and Other Physical Properties

Mention is made of those papers in which data are interpreted in terms of the electronic structure of the functional groups, their chemical properties,

or their conformational behaviour; data compilations are excluded Photoelectron Spectra.-Information on electronic structure may be ob- tained through this technique concerning interactions between a sulphur functional group and its neighbouring atoms, where d-orbital involvement has been inferred previously, often only tentatively, from chemical proper- ties C-S hyperconjugation (a-n mixing) is no more effective in ally1 methyl sulphide than analogous C-H hyperconjugation in propene, in contrast with the equivalent silane.21 Comparisons of photoelectron spectra

of H2S, RSH, and R2S show increasing delocalization of the sulphur lone pair with increasing s u b s t i t ~ t i o n , ~ ~ ~ ~ ~ but only a small effect of d-orbital bonding on the n-orbitals of the benzene ring in thiophenol” and no p,-d,

back-bonding in aryl methyl sulphides.”

R G Hiskey, V R Rao, and W G Rhodes, in ‘Protecting Groups in Organic Chemistry’, ed J

F W McOmie, Plenum Press, London, 1973, p 235

l o J L Kice, in ‘Free Radicals’, Vol 2, Wiley, New York, 1973, p 711; L A Singer, Selectiue Organic Transformations, 1972, 2, 239

I ’ B M Trost, Fortschr Chem Forschung, 1973, 41, 1

l 2 J I Musher, Ann New York Acad Sci., 1972, 192, 52

l 3 V P Litvinov, A N Sukiasyan, and Ya L Goldfarb, Khim geterotsikl Soedinenii, 1972,723

l4 K D Gundermann, Intra-Sci Chem Reports, 1972, 6, 91

l 5 Internat J Sulfur Chem (B), 1971,6; (a) C J M Stirling, p 277; (b) 0 N Soerensen, p 321;

ibid., 1972,7; (c) G Tsuchihashi, p 185; (d) F G Bordwell, p 187; (e) T Nagai, p 207; (f) J

W McFarland, p 319; Internat J Sulfur Chem (C), 1972,7; (g) G Modena, p 95; Internat J Sulfur Chem., 1973, 8; (h) J G Tillett, p 289; (i) N Isenberg, p 307

(a) G Scorrano, Accounts Chem Res., 1973, 6, 132; (b) C R Johnson, ibid., p 310

” J G Moffatt, in ‘Oxidation’, ed R L Augustine, Dekker, New York, 1971, p 1

’* G H Jones and J G Moffatt, Methods Carbohydrate Chem., 1972, 6, 315

l9 D Knoke, K Kottke, and R Pohloudek-Fabini, Pharmazie, 1973, 28, 574, 617

’O S Oae, G Tsukamoto, and T Kurusu, Kagaku (Kyoto), 1971, 26, 1066

21 W Schafer and A Schweig, J.C.S Chem Comm., 1972,824; Tetrahedron Letters, 1972,5205

*’ H Bock and G Wagner, Angew Chem Internat Edn., 1972, 11, 150; Chem Ber., 1974,107,

23 P Mollere, H Bock, G Becker, and G Fritz, J Organometallic Chem., 1973, 61, 127

24 D C Frost, F G Herring, A Katrib, C A McDowell, and R A N McLean, J Phys Chem.,

H Bock, G Wagner, and J Kroner, Chem Ber., 1972, 105, 3850

68

1972, 76, 1030

Aliphatic Organo-sulphur Compounds 3 Sulphimides carry a larger positive charge on sulphur than in the corresponding sulphoxides.26 Differences in functional-group polarization are found in the series dimethyl sulphone, sulphoximide, and sulphur di-imide, and in comparisons of MeS0,F with F,SO,, or of MeS0,CI with Cl,SO,.” ThrQugh-conjugation and spiro-conjugation between the sulphonyl group and 7r-orbitals of vinyl groups are shown by comparing dimethyl sulphone with methyl vinyl sulphone and divinyl sulphone.” However, the inductive effect of the sulphonyl group has a greater polarizing effect on neighbouring functional groups,

Dipole Moments.-Conformations of arene thiolsulphonates ArSS0,Ar and the corresponding thiolsulphinates’9b are ~imilal’”~”~ to that of a disulphide

(1) or a sulphinate in its preferred synclinal conformation; the stereo-

(1)

Thiolsulphinate: one oxygen in place of lone pair on one sulphur atom

Thiolsulphonate: two oxygen atoms in place of two lone pairs on one sulphur atom

chemical control exerted through gauche interaction of the two C-S

bonds is now well-established.”

a-Disulphones, RSO,SO,R,”b are also represented by (1; oxygen atoms in place of lone pairs), while gern-dis~lphones,~~~ diacyl s u l p h i d e ~ , ~ ~ ~

sulphonic anhydrides,”” and thioanhydrides are represented by (2), as

Y /x-Ar X- - -Ar

26 C E Mixao and J B Lambed, J Org Chem., 1973, 38, 1350

27 B Solouki, H Bock, and R Appel, Angew Chem Internat Edn., 1972, 11, 927

28 C Muller and A Schweig, Tetrahedron, 1973, 29, 3973

29 (a) 0 Exner, D N Harpp, and J G Gleason, Canad J Chem., 1972,50,548; (b) P Dembech,

P Vivarelli, V Jehlicka, and 0 Exner; J.C.S Perkin 11, 1973,488; (c) 0 Exner, P Dembech,

G Seconi, and P Vivarelli, ibid., p 1870; (d) 0 Exner, V Jehlicka, and J Firl, Coil Czech Chem Comm., 1972, 37, 466; (e) K Sindelar and 0 Exner, ibid., p 2734

30 A N Vereshchagin, L A Monetina, 1 I Lapkin, N S Zelenina, and B A Arbuzov, Izuest Akad Nauk S.S.S.R., Ser khim., 1973, 1765

4 Organic Compounds of Sulphur, Selenium, and Tellurium

diary1 d i s ~ l p h i d e s ~ ~ ~ * ' and di-2-pyridyl and di-4-pyridyl disulphides.""."

Nuclear Magnetic Resonance Spectra.-Natural-abundance "S n.m.r of representative sulphur compounds appears to offer little scope for struc- tural identification purposes; the broad absorption peaks render chemical-

13C Chemical shifts of ring-substituted phenyl vinyl etherP compared

the aromatic ring."

that the thiol proton resonance suffers a much smaller induced shift compared with alcohols, but the shift, at a maximum in CS, as solvent, is structure-dependent Sulphides also interact less strongly than correspond-

spectra of thiolsulphinates." Chiral Eu shift reagents permit the estimation

while the chiral-solvent technique is used42 for the same purpose with

nitrophenyl sulphide in the presence of Et4NCl is accompanied by an upfield shift for the CH, resonances, attributed to close contact with Cl-.*'

sive interaction between C1 and SAr,43" while an intramolecular attractive

3 1 Y Y Borovikov, Y P Egorov, A M Penchuk, and T A Khimchenko, Zhur org Khim.,

1973, 43, 2476

32 (a) G C Pappalardo and G Ronsisvalle, Tetrahedron, 1972,28,4147; J Mol Structure, 1973,

16, 167; (b) J.C.S Perkin 11, 1973,701; (c) G C Pappalardo and S Pistara, Tetrahedron, 1972,

28, 1611

33 C L Cheng and G L D Ritchie, Austral J Chem., 1973, 26, 1785

34 H L Retcofsky and R A Friedel, J Arner Chem SOC., 1972, 94, 6579

'' (a) H McFarlane, E Christina, and W McFarlane, J.C.S Dalton, 1973, 2416; ( b ) W

36 0 Kajimoto, M Kobayashi, and T Fueno, Bull Chern SOC Japan, 1973, 46, 1422

37 W A Sheppard and R W Taft, J Amer Chern SOC., 1972, 94, 1919

38 H Yanagawa, T Kato, and Y Kitahara, Tetrahedron Letters, 1973, 2137

39 T C Morrill, R J Optiz, and R Mozzer, Tetrahedron Letters, 1973, 3715

*' H Nozaki, K Yoshino, K Oshima, and Y Yamamoto, Bull Chem SOC Japan, 1972,45,3495

42 W H Pirkle and M S Pavlin, J.C.S Chem Comm., 1974, 274

43 J Hayami, N Tanaka, N Hihara, and A Kaji, Tetrahedron Letters, 1973, 385

43* G M Underwood, C T Watts, and C A Kingsbury, J Org Chem., 1973, 38, 1553; G M Underwood, A K Chan, T Green, C T Watts, and C A Kingsbury, ibid., p 2735; G M Underwood and C A Kingsbury, J.C.S Perkin

McFarlane and R J Wood, ibid., 1972, 1397

L E Legler, S L Jindal, and R W Murray, Tetrahedron Letters, 1972, 3907

Aliphatic Organo-sulphur Compounds 5

interaction is demonstratedu between a sulphone or sulphoxide group and

an alkoxide function, using hubstituted 1,3-dioxans, and its strength is of

about the same order as an intramolecular hydrogen bond for the sulphone Solution conformations are deduced for ring-substituted diphenyl sulphides and disulphides."

Protonation equilibria for aliphatic sulphoxides in H,SO,, as determined by n.m.r., compare well with data obtained earlier by U.V and c.d methods."se pKBH+ Values obtained similarly for sulphinates" and sulphides* have been reported; values for sulphides are some 4 units more positive than for

corresponding ethers, and a basicity order R,S > RSSR - RSH emerges,& in interesting contrast with the oxygen series (MeOH is more basic than MeOMe) "C N.m.r of DMSO and diethyl sulphoxide reveal O-protonation

in strong acid since both CH, and CH, resonances are shifted to higher field."

N.m.r data for s ~ l p h o n e s ~ ~ " and sulph~ximines"~ have been interpreted

Ultraviolet and Circular Dichroism Spectra.-U.v spectra of benzene-, toluene-, and mesitylene-thiols and derived alkyl sulphides show bands in the 205-230, 235-270, and 275-300 nm wavelength regions, which are structure- and solvent-sensitive;" a predominantly conjugative interaction between S and aryl chromophores is revealed, with solvent shifts attributed to hydrogen-bonding to S Detailed calculations have permitted assignments of transitions responsible for the absorption features near 200, 220, and 240 nm for simple alkyl sulphides."." Substituted aryl allyl sulphides and selenides show variations in

A,, related to Hammett u constants:' with electron-donating ability order allyl Se z= allyl 0 > allyl S Near-u.v absorption of sulphoxides has been discussed:2 and the thiolsulphinate absorption maximum

at 254nm (in hexane) has been exploited in estimation of the cysteine thiolsulphinate produced enzymically from S-allyl-L-cysteine sulphoxide present in ~ n i o n ~ '

The c.d of alkyl 2-phenylbutyl sulphides is interpreted in terms of

E Eliel and S A Evans, J Amer Chem SOC., 1972, 94, 8587

45 G C Pappalardo, Spectrochirn Acta, 1973, A29, 2055

46 (a) P Bonvicini, A Levi, V Lucchini, and G Scorrano, J.C.S Perkin 11, 1972, 2267; (b) R Curci, A Levi, V Lucchini, and G Scorrano, ibid., 1973,531; ( c ) P Bonvicini, A Levi, V

Lucchini, G Modena, and G Scorrano, J Amer Chem SOC., 1973,95,5960; ( d ) G Gatti, A Levi, V Lucchini, G Modena, and G Scorrano, J.C.S Chem Comm., 1973, 251; (e) P

Bonvicini, A Levi, and G Scorrano, Gazzetta, 1972, 102, 621

" G Montaudo, P Finocchiaro, E Trivellone, F Bottino, and P Maravigna, J Mol Structure,

1973, 16, 299; S Oae, K Harada, K Tsujihara, and N Furukawa, Internat J Sulfur Chem (A), 1972, 2, 49

18 I W Jones and J C Tebby, J.C.S Perkin IZ, 1973, 1125

49 J S Rosenfield and A Moscowitz, J Amer Chem Sac., 1972, 94, 4797

5 0 G L Bendazzoli, G Gottarelli, and P Palmien, J Amer Chem SOC., 1974, 96, 1 1

" G A Chmutova and V I Neonilina, Zhur fiz Khim., 1972, 46, 201

52 A Mangini, M Pallotti, M Tiecco, A Dondini, and P Vivarelli, Internat J Sulfur Chem (A),

G G Freeman and F McBreen, Biochem SOC Trans., 1973, 1, 1150

1972, 2, 69

6 Organic Compounds of Sulphur, Selenium, and Tellurium

interaction between phenyl and sulphur chromophores.s4 The optical active ity of cysteine and its derivatives has unusual features due to the sulphur chromophores, and a c.d study of common sulphur-containing amino-acids has been made." In particular, the high optical rotation of the disulphide L-cystine has been taken as evidence for a chiral disulphide grouping but it

is in fact due to accumulated optical rotatory power from three staggered rotamers in An inherently dissymmetric disulphide chromophore explanation is adopted for interpretation of the near-u.v c.d of disulphide- bridged peptides, and the temperature-dependence of the c.d of cystine derivatives is accounted for by changes of the dihedral angle;" the spacing

of the c.d bands of chiral disulphides is largest when the dihedral angle

is 0°.'8 Calculations" for orbital models of the chiral disulphide moiety provide estimates for rotation barriers in fair agreement with microwave data, and their u.v.-spectroscopic properties strongly reflect d-orbital par- ticipation in the excited states &sociated with the lowest-lying transitions.'" The right-handed screw-sense of the disulphide chromophore with dihedral angle 120" is associated with a negative c.d band near 240nm.s'd

Infrared Spectra.-A large batch of papers has appeared in the period under review concerning self-association of alkanethiolsm"*f and of thiophenols,m"e

as demonstrated by i.r, (and n.m.r.).60d-' Inert solvents, or weak oxygen* or nitrogenmb bases, were used, and temperature and concentration eff ectsmb

studied; apart from evidence for 1:l dimer formation in inert solvents,

SH - 0 association@' and SH n-bQnding in thiophenols,ma*g in PhCMsSH,md and between thiols and furanm' were demonstrated The proton-donor ability of the thiol proton and the protonacceptance ability of

bivalent sulphur have been reviewed in comparison with oxygen,6' also the proton-acceptor properties of alkyl isothiocyanates, which form hydrogen bonds through N." Pronounced hydrogen-bonding is found63 in NH,- C(:NH)S02H

1.r and Raman spectra of dialkyl disulphides" and benzyl sulphidess

5 4 P Biscarini, G Gottarelli, B Samori, and G D Nivellini, Tetrahedron, 1972, 28, 4139

5 5 G Jung, M Ottnad, and M Rimpler, European J Biochem., 1973, 35, 436

" J P Casey and R B Martin, J Amer Chem Soc., 1972, 94, 6141

" T Takagi, R Okano, and T Miyazawa, Biochim Biophys Acta, 1973, 310, 11

'' L A Neubert and M Carmack, J Amer Chem Soc., 1974, 96, 943

59 (a) D B Boyd, J Amer Chem Soc., 1972,94,8799; (b) Theor Chim Acta, 1973,30,137; (c)

J Webb, R W Strickland, and F S Richardson, J Amer Chem SOC., 1973,95,4775; (d) R

W Woody, Tetrahedron, 1973, 29, 1273

6o (a) R Bicca de Alencastro and C Sandorfy, Canad J Chem., 1972,50,3594; (b) ibid., 1973, 51,985; (c) R Bicca de Alencastro, ibid., 1974,52,738; (d) 0 P Yablonskii, L F Lapuka, N

M Rodionova, and V E Mazaev, Zhur priklad Spectroskopii, 1973,19,565; (e) ibid., p 750;

(f) S J Hu and S I Miller, Org Magn Resonance, 1973.5, 197; (g) G Geiseler, H Seidel, and

J Fruwert, Spectrochim Acta, 1973, A29, 1385

I Zuika and J Bankovskis, Uspekhi Khim., 1973, 42, 39

62 S Stankovsky, S Kovac, M Dandarova, and M Livar, Tetrahedron, 1973, 29, 1825

D de Filippo, G Ponticelli, E F Trogu, and A Lai, J.C.S Perkin 11, 1972, 1500

a H Sugeta, A Go, and T Miyazawa, Bull Chem Soc Japan, 1973, 46, 3407

K Doerf€el and B Adler, J prakt Chem., 1972, 314, 401

Aliphatic Organo-sulphur Compounds 7

provide conf ormational information, and aliphatic sulphides" and di- sulphones RSO,(CH,),SO,R" ( n = 1-6) have been studied with the same objectivẹ 1.r data feature prominently in studies of electronic interactions

in vinyl sulphides,"" meta-substituted benzenethiolsab and related sul- phides,"b and meta- and para-substituted methyl phenyl sulphoxides and sulphones."' Sulphur d-orbital acceptance is identified for phenyl sul- phides, sulphoxides, and sulphones where the phenyl group carries a strongly electron-donating substituent,"bsc while substituted analogues less capable of relaying charge to the sulphur grouping show MeSQ, to be a resonance acceptor while MeSO, SMe, SH, and SBú are resonance donors Mass Spectrạ-While most papers eligible for citation in this section could

be described as routine and useful, unusual features are to be found in the mass spectra of many organosulphur compounds Vinyl sulphides share the unusual mechanistic aspects by which the mass spectra of their oxygen analogues are interpreted,69n'b though the base peak at m/e 60 is MeCH=S* when H is transferred from position 2 in pentyl vinyl sulphide, and CH,==CHSH* when H is transferred from positions 3 or 4,69b though this was earlier assigned to the former.69" S-Migration occurs in the molecular ion of ethyl thĩbenzoate,~~" and S to 0 migration in styryl sulphoxides and sulphones on electron impact." An example of the ortho-effect, loss of C1 from the molecular ions of chloro diphenyl ethers, sulphides, and sul- phoxides, is not observed in corresponding sulphanes, which take a more favourable rearrangement path."

Mass spectra of sulphinate esters and isomeric sulphones are clearly differentiated." A preliminary communication of the results of ion cyclotron resonance studies of 2 - methoxyethanethiol and related compounds de- scribes gas-phase reactions involving CH,=O-Mẹ"

Similarities are noted between the mass spectra of aliphatic and aromatic selenides with analogous sulphides and ph~sphines.~~" Selenoxides show the expected fragments derived from the selenate rearrangement pr~duct.~"' Extensions of these studies cover selenium dihalides (no molecular ion is

and selenonẽ.~~' Mass spectra of

diary1 tellurides are very much like those of S and Se analoguệ^^

seleninic acids and

66 M Ohsaku, Y Shiro, and H Murata, Bull Chem SOC Japan, 1972, 45, 3480

67 K Dathe, K Doerffel, and Ẹ Muller, Z Chem., 1972, 12, 425

(a) Ạ R Katritzky, R F Pinzelli, and R D Topsom, Tetrahedron, 1972,28,3441; (b) N C Cutress, T B Grindley, Ạ R Katritzky, and R D Topsom, J.C.S Ferkin 11,1974,263; ( c ) N

C Cutress, T 8 Grindley, Ạ R Katritzky, M Shome, and R D Topsom, ibid., p 268

" (a) M Katoh, D Ạ Jaeger, and C Djerassi, J Amer Chem SOC., 1972,94, 3107; (b) K B Tomer and C Djerassi, ibid., 1973, 95, 5335; ( c ) Org Mass Spectrometry, 1973, 7, 771

'' T H Kinstle and W R Oliver, Org Mass Spectrometry, 1972, 6, 699

'' 1 Granoth, J.C.S Ferkin 11, 1972, 1503

72 W H Baarschers and B W Krupay, Canad J Chem., 1973, 51, 177

73 J K Kim, J K Pau, and M C Caserio, J.C.S Chem Comm., 1974, 121

74 (a) Ẹ Rebane, Acta Chem Scand., 1973,27,2861; (b) ibid, p 2870; ( c ) Chemica Scripta, 1973,

4, 219; (d) ibid., 1974, 5, 5; (e) ibid., p 65

8 Organic Compounds of Sulphur, Selenium, and Tellurium Electron Spin Resonance Spectra.-The complexity of reaction mixtures from ceric ion oxidation of thiols is clearly demonstrated by e.s.r.; in repre- sentative cases76 at least seven different species can be recognized Ti"*-H,O, oxidation of /3 -hydroxy-sulphides produces both C- and S- centred radicals," while studies of syn- and anti-a-sulphonyliminoxyl

radicals'' and alkylsulphinyl and alkylsulphonyl radical^'^ deal with cleaner samples

Continuing interest in rotation barriers about single bonds in acyclic radicals, as determined by the interpretation of e.s.r data, is illustrated in a study of R1CHSR2 radicalsm and alkane-, arene-, and alkoxy-sulphonyl radicals (obtained" by high-intensity U.V irradiation of sulphinic acids in the presence of di-t-butyl peroxide at low temperatures) Further evidence for hindered rotation about the C-S bond in these species is obtained,80-8' and

an unusual order of proton hyperfine splittings la1 (P-H)>lal (a-H)-

la1 (y -H) is reported" for propanesulphonyl radicals The potential of the e.s.r method in conformational analysis is shown in studies of radical cations (3) from 2,5-bis(alkylthio)thiophens, where the S-cis-cis conformer

(3) is identified as more stable than other rotamers;'* this is assumed to be the case too for the neutral molecule

Other Physical Studies.-Bond lengths in 4-dimethylaminophenyl phenyl sulphide between S and C are shorter than in other diary1 sulphides,83 and a conclusion is drawn that sulphur 3d orbitals are not involved in conjugation with neighbouring rr-systems The bond energy of the C-Se bond in dibenzyl diselenide is 57kcal mol-' from heat of combustion and heat of sublimation measurements.s4

Thermodynamic acid dissociation constants for a series of thiophenols correlate well with the Hammett a-constants of ring s ~ b s t i t u e n t s , ~ ~ and pK, values for aryl P-disulphones and p-keto-sulphones in DMF vary with substitution patterns in the aryl moiety, indicating conjugation through the

76 J C Kertesz, W Wolf, and H Hayase, J Magn Resonance, 1973, 10, 22

77 B C Gilbert, J P Larkin, and R 0 C Norman, J.C.S Perkin I!, 1973, 272

J J Zeilstra and J B F N Engberts, Tetrahedron, 1973, 29, 4299

79 T Kawamura, P J Krusic, and J C Kochi, Tetrahedron Letters, 1972, 4075

E A C Lucken and B Poncioni, Helv Chim Acta, 1972, 55, 2673

A G Davies, B P Roberts, and B R Sanderson, J.C.S Perkin I!, 1973, 626

C M Camaggi, L Lunazzi, and G Placucci, J.C.S Perkin 11, 1973, 1491

83 G Bandoli, D A Clemente, E Tondello, and A Dondini, J.C.S Perkin !I, 1974, 157

M R Arshadi and M Shabrang, J.C.S Perkin I!, 1973, 1732

P De Maria, A Fini, and F M Hall, J.C.S Perkin I!, 1973, 1%9

Aliphatic Organo-sulphur Compounds 9

sulphone grouping.86 The origin of the enhancement of the acidity of a CH group adjacent to sulphur has a satisfactory theoretical basks7 A p-amino- group enhances the acidity of an alkanethiol.88

Electron-diff raction studies for dimethyl sulphoneS9 and polarographic data for alkenes and alkynes bearing sulphonium, sulphinyl, and sulphonyl groupsgo are reported Data of practical importance in analysis have been obtained for the relationship of structure of bivalent sulphur compounds

to the temperature-dependence of the electron-capture me~hanism.~'

3 Thiols

Preparations.-a-Mercapto-a-amino-acids R'NHCR2(SH)C02H are ob- tained from corresponding chloro-compounds" or from 4-chloro-oxazol- 5(4H)-0nes.~~ Conventional methods are also used for synthesis of thio- resorcinols (from benzene- 1,3-disulphonic acids via sulphonyl chlorides, reduced with red P-12-AcOH,'" or from resorcinols via Newman-Kwart rearrangement of 0-dimethylaminothiocarbonyl-resorcinols followed by alkaline hydrolysis9') Dithiols are unexpectedly obtained" from ethyl a - acetonylacetate by treatment with H2S in acid solution at -40 "C Mercapto- ethylation of aliphatic amines is best achieved by a modification of the well-established method using episulphides, in aqueous solution in the presence of a silver salt." Methyl sulphides ArSMe may be demethylated by chlorination to ArSCC1, followed by acid methanolysis," while aryl diphenylmethyl sulphides are susceptible to electrolytic reduction to the

t hiophenol

A variation of the use of thiourea for converting alkyl halides into thiols uses N-acetylthiourea;'" although reaction with an alkyl halide in refluxing EtOH is slow, a separate hydrolysis step is not required and the method may prove useful for the synthesis of water- or alkali-sensitive thiols Other methods based upon thiocarbonyl derivatives are exemplified by the addition of allylic Grignard reagents to thioketones, giving &-unsaturated

86 V M Neplynev, V P Kukhar, R G Dubenko, and P S Pelkis, Zhur osg Khim., 1972, 8,

87 S Wolfe, L M Tel, and I G Csizmadia, Theor Chim Acta, 1973, 31, 355

2174

Y L Kostyukovskii, Y A Bruk, L V Pavlova, N M Slavachevskaya, A V Kokushkina, B

S Mirkin, and I A Belenkaya, Zhur obshchei Khim., 1972, 42, 662

R W Howsam and C J M Stirling, J.C.S Perkin 11, 1972, 847

89 M Hargittai and I Hargittai, J Mol Structure, 1974, 20, 283

9' M Satouchi and T Kojima, Analyt Letters, 1972, 5, 931

92 S M Patel, J 0 Currie, and R K Olsen, J Org Chem., 1973, 38, 126

93 P M Pojer and I D Rae, Austral J Chem., 1972, 25, 1737

94 F Voegtle, R G Lichtenhaler, and M Zuber, Chem Ber., 1973, 106, 719

95 H J Kurth, U Kraatz, and F Korte, Chern Ber., 1973, 106, 2419

% F Duus, Acta Chem Scand., 1973, 27, 466

97 R Luhowy and F Meneghini, J Org Chem., 1973, 38, 2405

98 J M Lavanish, Tetrahedron Letters, 1973, 3847

99 G Farnia, A Ceccon, and P Cesselli, J.C.S Perkin 11, 1972, 1016

D L Klayman, R J Shine, and J D Bower, J Org Chem., 1972, 37, 1532

10 Organic Compounds of Sulphur, Selenium, and Tellurium

thiols"' (see also ref 188b), and synthesis of adamantane-2-thiol from the thione by treatment with Bu"Li followed by aqueous acid."' Only about 5%

2-adamantyl butyl sulphide is formed in this reaction, while use of PhLi gives ca 25% thiol and 75% su1phide.'O2 Useful syntheses based upon the thiobenzophenone dianion Ph&S include the synthesis of Ph,C(SH)- C0,H by its reaction with C02.'03 An unusual photochemical addition of

acrylonitrile to the 4-thiouracil derivative (4) gives the thiol ( 5 ) and its geometrical isomer.'04

NC, ,CH,SH

Ring-opening of sulphur heterocycles to give thiols is illustrated in recent papers by thiazole cleavage (Na-NH, gives substituted propenethiolate~),'~~ thiophen cleavage (6) + (7),'06 and a novel penicillin cleavage reaction, potassium benzylpenicillinate with mercury(I1) acetate in AcOH giving (8) '07

lo' M Dagonneau and J Vialle, Tetrahedron, 1974, 30, 415,

'02 V Rautenstrauch, Helv Chim Acta, 1974, 57, 496

Io3 Y Minoura and S Tsuboi, J Org Chem., 1972, 37, 2064

Io5 S Hoff and A P Blok, Rec Trau chim., 1974, 93, 18

J L Fourrey, P Jouin, and J Moron, Tetrahedron Letters, 1973, 3229

R Heckendorn and A R Gagneux, Tetrahedron Letters, 1973, 2279

R J Stoodley and N R Whitehouse, J.C.S Chem Cornm., 1973, 477; J.C.S Perkin I, 1974,

181

D M E Reuben and T C Bruice, J.C.S Chem Comm., 1974, 113

lo' A Behzadi and L N Owen, J.C.S Perkin I, 1973, 2733

Aliphatic Organo-sulphur Compounds 11 involved in drug metabolism and tyrosine biosynthesis The four isomers of

dibenzylmercaptocyclohexanediol obtained by reaction of the cis-trans-

mixture of cyclohexa-l,4diene dioxide with PhCH,SNa have been isolated and characterized."'

One or both vinylic fluorines in CF,CR=CF, can be substituted by reaction with a sodium thiolate."' Corresponding reactions with arylhalo- geno-alkynes proceed uia an a-addition-dimination mechanism,"' but with 2-chloro- or -bromo- 1,l-diphenylpropenes an allenic elimination-addition mechanism is ruled out (though this path is followed by the corresponding reaction with phenoxides)."' Selective homotropic intermolecular hydrogen- bonding in alkyl halides in Cl(CH,), or "CONHCONHR mixtures accounts for the exclusive formation of symmetrical bis-sulphides with ethane- 1,2- dithiol."' Reductive dehalogenation of aryl halides by thiophenol,"' and substitutions of pentachloro- and polychlorofluoro-pyridines'I6 and 4-sub-

four-centre concerted mechanism is proposed''' for the reaction of PhHgSPh with picryl chloride Demethylation of bromo-anisoles with NaSEt gives bromophenols.'""

The greater reactivity of sulphur nucleophiles, compared with their oxygen analogues, towards methyl benzenesulphonate,'" and the 10'-fold rate enhancement in the reaction of long-chain alkanethiols with p - nitrophenyl acetate in the presence of stearyl trimethylammonium bromide, above the critical micellar concentration,12' are the subjects of recent papers dealing with nucleophilic attack by thiols on esters Steric effects have been assessed for their influence on the nucleophilicity of alkyl-substituted ben- zenethiolate anions towards N-ethylmaleimide"' and towards disulphides."' Reactions of cysteine and cysteamine with H,O, show kinetics charac- teristic of nucleophilic attack of the thiolate at oxygen;"' the rate decreases

as the pH is raised, and this suggests that hydrogen-bonding between the peroxide and -NH: facilitates the reaction

' I o G E McCasland, A K M Anisuzzaman, S R Naik, and L J Durham, J Org Chem., 1972,

'I1 S R Sterlin, V M Izmailov, V L Isaev, A A Shal, R N Sterlin, B L Dyatkin, and I L

'Iz P Beltrame, P L Beltrame, M G Cattania, and M Simonetta, J.C.S Perkin 11, 1973, 63

' I 3 M Ballabio, P L Beltrame, and P Beltrame, J.C.S Perkin 11, 1972, 1229

'I4 T Mukaiyama, T Endo, Y Kojima, and T Sato, J Amer Chem SOC., 1972, 94, 7575; T

Endo, T Sato, S Sato, and T Mukaiyama, Chem Letters, 1W3, 1201

'I5 M W Barker, S C Lauderdale, and J R West, J Org Chem., 1972, 37, 3555

J Bratt and H Suschitzky, J.C.S Perkin I , 1973, 1689

I " P Carniti, P Beltrame and S Cabiddu J.C.S Perkin I I 1973, 1430

'18 C Dell'Erba, G Guanti, M Novi, and G Leandri, J.C.S Perkin 11, 1973, 1879

I l 9 A Kyllonen and J Koskikallio, Suomen Kern., 1972, 45, B, 212,

I2O W Tagaki, T Amada, Y Yamashita, and Y Yano, J.C.S Chem Comm., 1972, 1131

12' D Semenow-Garwood, J Org Chem., 1972, 37, 3797

122 D Semenow-Garwood, and D C Garwood, J Org Chem., 1972, 37, 3804

J P Barton, J E Packer, and R J Sims, J.C.S Perkin 11, 1973, 1547

37, 1201

Knunyants, Zhur Vsesoyuz Khim obshch im D.I Mendeleeva, 1973, 18, 710

G I Feutrill and R N Mirrington, Austral J Chem., 1972, 25, 1719

12 Organic Compounds of Sulphur, Selenium, and Tellurium Ađition Reactions of Thiols.-Ethylthiopicrate ađs EtS- to give the first

gem-di(alky1thio) analogue (9) of a Meisenheimer ađuct.’” Thiophenoxide- 1,3,5-trinitrobenzene ađucts (heats of formation have been measured”’)

are in equilibrium with their component species, and carbon basicity values derived from equilibrium constants are in good agreement with the nucleo- philic reactivities of substituted thiophenoxides derived from their reaction with l-chloro-2,4-dinitrobenzenẹ””

Base-catalysed ađition to aryl vinyl sulphones sets up the order PhO- < HO- < EtO- 4 PhS- (relative nucleophilicities 1 : 20 : 378 : 37 800) 12’ Various forms of acid catalysis can be used; with TiCL, EtSH ađs to vinyl ketones

to give p-ethylthio-ketones,’** and acid-catalysed ađition of thiols to the

ap -unsaturated carbonyl grouping in dehydrocyclodipeptides gives a-

ađucts under kinetic control, which slowly isomerize to (3-ađ~cts.l~~ Ger- macrone and acoragermacrone (sesquiterpene vinyl ketones), in ađing

PhSH from AcOH solution, undergo cyclization to guiaine derivativệ'^' Thiolate anions ađ in trans fashion to cycl~hexenes,’~~ 4-t-butyl- l-cyano- cyclohexene giving an ađuct with axial PhS.”’*

Cysteine-catalysed H-D exchange at the 5-position of uridylic acid is rationalized by an ađition-elimination sequence (10) + (1 l).”’

G Biggi and F Pietra, J.C.S Perkin I, 1973, 1980; J.C.S Chem Comm., 1973, 229

’” J W Larsen, K Amin, S Ewing, and L L Magid, J Org Chem., 1972, 37, 3857

M R Crampton and M J Willison, J.C.S Perkin 11, 1974, 238

P De Maria and Ạ Fini, J.C.S Perkin 11, 1973, 1773

T Mukaiyama, T Izawa, K Saigo, and H Takei, Chem Letters, 1973, 355

129 P J Machin and P G Sammes, J.C.S Perkin I, 1974, 698

130 (a) M Iguchi, M Niwa, and S Yamamura, Tetrahedron Letters, 1973, 1687; (b) ibid., p 4367

13’ (a)Ạ van Bruijnsvoort, Ẹ R de Waard, J L van Bruijnsvoort-Meray, and H 0 Huisman, Rec Traụ chim., 1973, 92, 937; (b) R Ạ Abramovitch, M R Rogic, S S Singer, and N Venkateswaran, J Org Chem., 1972, 37, 3577

Ỵ Wataya, H Hayatsu, and Ỵ Kawazoe, J Amer Chem SOC., 1972, 94, 8927