ru ii catalyzed enantioselective hydrogen transfer

... pharmaceuticals and drug To date, the examples of phase -transfer catalyzed enantioselective direct aldol reactions are quite limited Maruoka’s group developed an efficient, highly diastereo-and enantioselective ... Generally, in asymmetric phase -transfer catalysis, two representative mechanisms were proposed for phase -transfer catalyzed reactions First one is base catalyzed phase -transfer reactions Typically, ... cyanide or anhydrous hydrogen cyanide In the regard of green chemistry and practical usage, phase -transfer catalyzed enantioselective Strecker reaction using KCN is highly desirable Maruoka and co-workers...

Ngày tải lên: 09/09/2015, 17:53

... towards various phase -transfer catalyzed reactions In the additive screening experiments, it was found that CsCl played a role of rate enhancement in the phase -transfer catalyzed conjugate additions ... salt 57 as phase -transfer catalyst Scheme 2.4 Chiral binaphthyl-derived bis(ammonium) salt 58 as phase -transfer catalyst Scheme 2.5 Tartrate-derived bis(ammonium) salts 59 as phase -transfer catalysts ... synthesized by enantioselective conjugate addition of glycinate derivatives by chiral phase -transfer catalysis Corey et al utilized cinchonidinium bromide 11 as a chiral phase -transfer catalyst...

Ngày tải lên: 09/09/2015, 17:53

... occurrence of stereogenic cyclic aminals and similar 71 Chapter structures in drugs and other compounds of use and the lack of available enantioselective routes toward their preparations, asymmetric ... a facile route to the construction of fluorinated quaternary stereogenic centers (Scheme 3.7) Scheme 3.7 Enantioselective amination of fluorinated aromatic ketone catalyzed chiral bicycic guanidine ... be easily achieved by 76 Chapter phase -transfer catalysis Maruoka’s group reported a new binaphthyl-derived quaternary phosphonium salt as chiral phase -transfer catalyst, which shows excellent...

Ngày tải lên: 09/09/2015, 17:53

... Benzophenone Imines of Phosphoglycine Ester7 124 Chapter (i) Toluene reflux, Na2SO4, 95%, (ii) Diisopropylphosphite, 92%; (iii) DDQ, Å Molecular Sieves, Toluene, 99% To a solution of diphenylmethanamine ... solvent, the crude product was purified by flash chromatography Products obtained are known compounds.6 105 Chapter 4.2.4 Representative Procedure for Phase Transfer Michael Addition Reactions Catalyzed ... in oven-dried glassware equipped with a rubber septum inlet Air sensitive reagents were weighed in a glovebox Dried solvents and liquid reagents were transferred by oven-dried syringes or hypodermic...

Ngày tải lên: 09/09/2015, 17:53

Ngày tải lên: 09/09/2015, 17:53

... for Pd(0) -catalyzed cross-coupling reactions O R1 R2 R Pd0 PdII Ar PdII X R Nu Ar R1 R2 LG Nu O Ar Nu X H PdII R1 O PdII Ar R2 Pd(0) base R1 R R1 R sy n-Hydride Elimination PdIIX H PdII (d) Ar ... Reductive Elimination PdII L L PdIV I R' Oxidative Addition II IV (Pd /Pd ) PdII R'I (PdII/PdIV) R R' PdII R' R' R' β Alkyl II Pd Elimination R' R R' Pd0 Heck Coupling The Pd(0)/Pd (II) /Pd(IV) ‘cascade ... Canty N b) Sanf ord Me PdII N Me MeI N Me PdIV N Me N N PhI(OAc)2 PdII Me N N PdIV OAc I OAc X ray structure X ray structure Scheme 1.14 Pd (II) /Pd(IV) catalytic cycle R R1 PdII RH CH Activation Reductive...

Ngày tải lên: 09/09/2015, 11:25

... 221 III Summary The aim of this study is to develop guanidine catalyzed highly enantioselective Mannich reactions Inspired by nature, we developed chiral bicyclic guanidine catalyzed biomimetic ... - 87 II Chapter Bicyclic Guanidine Catalyzed Fluorocarbon Nucleophiles Enantioselective Mannich Reaction of 4.1 Fluorocarbon Nucleophiles 92 Enantioselective ... 83c and imine 86a Table 4.1 Highly enantioselective and diastereoselective Mannich reactions of fluorocarbon nucleophiles VIII List of Figures Figure 1.1 Structures of compounds 46 and 47 Figure...

Ngày tải lên: 10/09/2015, 08:31

... Chiral guanidine 57 catalyzed nitro Michael reaction Scheme 1.12 Terada’s axially chiral guanidine catalyzed enantioselective reactions Scheme 1.13 Guanidine salt catalyzed phase transfer asymmetric ... salt catalyzed phase transfer asymmetric alkylation Scheme 1.15 Guanidine salt catalyzed enantioselective Phospha-Mannich reactions Scheme 1.16 Conjugate additions of pyrrolidine to lactones 79 catalyzed ... Figure 2.5 Hydrogen bonding pattern between guanidinium groups and oxoanions revealed by crystal X-ray structures: I) guanidinium with phosphates; II) guanidinium with carboxylates; III) guanidinium...

Ngày tải lên: 11/09/2015, 09:17

... X-ray structure of 81c Figure 2.5 Structure of aziridine-2,3-dicarboxylate and aspartic acid Figure 3.1 General structure of dithiocarbamate Figure 3.2 Structure of fluoxetine Figure 5.1 Structure ... γ-lactones by enantioselective intramolecular Michael addition reactions of α,β-unsaturated carbonyl compounds 102 viii List of Figures Figure 2.1 General sturcture of guanidine Figure 2.2 Structural ... benzenethiol 63c catalyzed by guanidine 79b Table 2.11 Desymmetrization of cis-aziridine-2,3-dicarboxylate 91d with various thiols catalyzed by guanidine 79b Table 3.1 Chiral guanidine 79b catalyzed...

Ngày tải lên: 11/09/2015, 10:05

... Chapter 2.1 Bicyclic guanidine catalyzed enantioselective desymmetrization of meso N-tosyl aziridines with thiols 2.1.1 Bicyclic guanidine catalyzed enantioselective reactions Guanidine ... racemization Scheme 2.12 Chiral bicyclic guanidine catalyzed Diels-Alder reactions of anthrones.21 32 Chapter 2.1.2 Bicyclic guanidine catalyzed enantioselective desymmetrization of meso N-tosyl ... O-protected aminoindanols 2.3 Guanidine catalyzed enantioselective desymmetrization of meso N-acyl aziridines with thiols 2.3.1 Optimization studies on the enantioselective desymmetrization of meso...

Ngày tải lên: 11/09/2015, 10:05

... anti-Trichomonas activities Figure 3.2 Structure of fluoxetine Scheme 3.4 Synthesis of carbodithioic acid esters of fluoxetine 63 Chapter 3.2 Guanidine catalyzed enantioselective desymmetrization of ... 3.2.1 Optimization studies on the enantioselective desymmetrization of meso-aziridines with in situ generated carbamodithioic acids Table 3.1 Chiral guanidine 79b catalyzed desymmetrization of meso ... increasing interest in synthetic organic chemistry during the past few years Figure 3.1 General structure of dithiocarbamate General methods for the synthesis of dithiocarbamate derivatives involved...

Ngày tải lên: 11/09/2015, 10:05

... with rubber septa and reactions were conducted under a positive pressure of nitrogen, unless otherwise noted All solvent distillation was done at 760 Torr Toluene, THF, diethyl ether and diisopropyl ... mL) was added Pd(OH)2/C (170 mg) Bubbling of hydrogen gas for 15 minutes, the reaction was stirred for a further hours under a positive atmosphere of hydrogen gas (balloon) The reaction mixture ... BÜCHI B-540 melting point apparatus Single crystal X-Ray diffraction studies were obtained on a Bruker-AXS Smart Apex CCD single-crystal diffractometer 4.2 Preparation of the aminoindanol derived...

Ngày tải lên: 11/09/2015, 10:05

... Figure 5.1), which has been widely found in natural compounds, are interesting lead structures for new drugs due to the broad scope of their biological activities including antibiotic, antihelmetic, ... equivalent dicyclohexylcarbodiimide (DCC) afforded the desired α,β-unsaturated carbonyl compounds 102.11 Scheme 5.4 Synthesis of donor–acceptor functionalized substrates 102 5.3 TBD catalyzed intramolecular ... carbonyl compounds 102 towards base -catalyzed intramolecular Michael addition reactions by using TBD as the catalyst for the racemic reactions Table 5.1 TBD catalyzed intramolecular Michael addition...

Ngày tải lên: 11/09/2015, 10:05

... 60 catalyzed enantioselective Strecker reaction Scheme 2.2 Enantioselective transamination reactions of an imine catalyzed by bicyclic guanidine 60 Scheme 2.3 Bicyclic guanidine 65 catalyzed enantioselective ... 17 1.4.2 Molybdenum -Catalyzed Asymmetric Allylic Alkylations - 21 1.5 Organocatalyst Catalyzed Enantioselective Allylic Addition - 27 Chapter Bicyclic Guanidine Catalyzed Direct Asymmetric ... trichlorosilanes to aldehydes catalyzed by 17 Scheme 1.16 Addition of allyltrichlorosilane catalyzed by N-Oxide Scheme 1.17 Mo -catalyzed asymmetric allylic alkylation Scheme 1.18 Mo -catalyzed asymmetric...

Ngày tải lên: 12/09/2015, 09:07

... Chapter 2 Enantioselective Protonation Reactions Catalyzed by Chiral  Bicyclic Guanidine  Enantioselective Protonation Reactions Catalyzed by Chiral Bicyclic Guanidine  2.1 Catalytic Enantioselective Protonation Reactions  ... List of Figures  List of Abbreviations  Chapter 1 Chiral Guanidines Catalyzed Enantioselective Reactions  Chiral Guanidines Catalyzed Enantioselective Reactions  1  1.1 Introduction  2  1.2 Chiral Guanidines as Asymmetric Catalysts  ... CHIRAL GUANIDINE CATALYZED ENANTIOSELECTIVE PROTONATION REACTIONS    LEOW DASHENG JACKSON  2009  CHIRAL GUANIDINE CATALYZED ENANTIOSELECTIVE PROTONATION REACTIONS   ...

Ngày tải lên: 12/09/2015, 10:17

... phosphorus compounds5, which limits the scope of the enantiopure organophosphorus compounds The direct approach to build phosphorus-carbon (P-C) bonds, which was a convenient method to generate structurally ... organophosphorus chemistry Wiley: New York, 2000; p x, 394 p (a) Tang, W.; Zhang, X Chem Rev 2003, 103, 3029–3069 (b) Crepy, K V L.; Imamoto, T., In New Aspects in Phosphorus Chemistry Iii, 2003; ... Ph2PH/BuLi (1.8 euqiv.), THF, -78 oC, 3h, then Na2SO4 10H2O; (b) i BH3.THF, -50 oC; ii CF3CO2H, then NaOH, 90%; iii NaH, THF, 25 oC, BH3.THF, -78 oC, 1N HCl; (c) DABCO, 1.1 eq., 100 oC, 1h Feringa...

Ngày tải lên: 14/09/2015, 08:38

... 110 NH iv t iii i, ii t N H I114b.HI Bu vii t Bu N t Bu N N H 114b (base) Scheme 2.3 Synthesis of symmetrical chiral bicyclic guanidines Reagents and conditions: (i) TsCl, Et3N, MeCN; (ii) MsCl, ... MeCN; (ii) MsCl, Et3N, DMAP, DCM, rt; (iii) NH3/MeOH, oC to rt; (iv) MeCH, 90 oC, days; (v) Na/NH3, -78 oC; (vi) (MeS)2C=S, MeI/AcOH, MeNO2, reflux; (vii) K2CO3 column Our group employed the ... obtained in all examples 2.3 Bicyclic guanidine -catalyzed phospha-Michael enantioselective reactions The phospha-Michael reactions employing phosphorus nucleophiles such as phosphonates were investigated...

Ngày tải lên: 14/09/2015, 08:38

... Chapter 3.1 Hydrogen bond donors catalyzed asymmetric reactions Electrophilic activation by small-molecule hydrogen bond donors has provided an important paradigam for design of enantioselective ... P OTMS 176 ii OH O P Bn H OH O P Bn Bn 177 178 iii OBn O P Bn H 179a Scheme 3.6 Synthesis of benzyl benzylphosphinate Reagents and conditions: (i) 1.05 eq (TMS)2NH, 110 oC, 1-2h; (ii) 0.5 eq ... CO2 tBu NO Scheme 3.3 Johnston’s chiral proton catalyst catalyzed enantioselective direct aza-Herry reaction 3.2 Chiral guanidinium salt catalyzed phospha-Mannich reactions The addition of phosphonates...

Ngày tải lên: 14/09/2015, 08:38

... Protocol for bicyclic guanidine -catalyzed phospha-Michael reactions and characterization of phospha-Michael reaction products 4.4.1 Protocol for bicyclic guanidine -catalyzed phospha-Michael reactions ... ether (x 6) Acidify the aqueous layer with HBF4 solution (Caution: CO2 generated!) until PH = The crude product was collected via reduce pressure filtration and purified by 87 Chapter recrystallization ... Chapter 4.1 General Procedures H and 13 C NMR spectra were recorded on a Bruker ACF300 (300MHz) or AMX500 (500MHz) spectrometer Chemical shifts are reported in parts per...

Ngày tải lên: 14/09/2015, 08:38

... F VIII p-cymene Ruthenium (II) NHC complexes i [RuCl2(η -p-cymene)( Pr2-imy)] i [RuCl2(η -p-cymene)( Pr2-bimy)] 6 [RuCl2(η -p-cymene)(Bn2-bimy)] me [RuCl(η -p-cymene)(κ C,C-diNHC )][PF6] et [RuCl(η ... p-cymene Ru( II) NHC complexes 19 2.1.1 p-cymene Ru( II) NHC complexes bearing monodentate NHC ligands 19 2.1.2 p-cymene Ru( II) NHC complexes bearing bidentate NHC ligands 22 2.2 Catalytic hydrogenation ... and angles []: Ru( 1)-C(4) 2.041(4), Ru( 1)-C(6) 2.047(4), Ru( 1)-Cl(1) 2.413(1), Ru( 1)-Ct1 1.739, C(4) -Ru( 1)-C(6) 83.3(2), N(2)-C(1)-N(3) 109.9(4), C(4) -Ru( 1)-Cl(1) 86.3(1), C(6) -Ru( 1)-Cl(1) * 86.3(1)...

Ngày tải lên: 01/10/2015, 17:27