A thermoregulated phase transfer chiral Pt nanocatalyst for enantioselective hydrogenation of α-ketoesters

2020 ◽  
Vol 10 (23) ◽  
pp. 7824-7828
Author(s):  
Pu Chen ◽  
Yanhua Wang
Keyword(s):  
Phase Transfer ◽  
Enantioselective Hydrogenation

An efficient and recyclable thermoregulated phase transfer chiral Pt nanocatalyst was developed and applied to the enantioselective hydrogenation of α-ketoesters.

Enantioselective Construction of Alkylated Stereogenic Centers

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Phase Transfer ◽  
Enantioselective Hydrogenation ◽  
Gel Chromatography ◽  
Quaternary Centers ◽  
University Of Oxford ◽  
University Of Edinburgh ◽  
Enantioselective Alkylation ◽  
Silica Gel Chromatography ◽  
University Of Bristol ◽  
The University

Xiang-Ping Hu and Zhuo Zheng of the Dalian Institute of Chemical Physics developed (Organic Lett. 2009, 11, 3226; J. Org. Chem. 2009, 74, 9191) a family of Rh catalysts for the enantioselective hydrogenation of allylic phosphonates such as 1. Hon Wai Lam of the University of Edinburgh established (J. Am. Chem. Soc. 2009, 131, 10386) that an alkenyl heterocycle 3 could be reduced with high ee. The product 4 could be hydrolyzed to the carboxylic acid. Ken Tanaka of the Tokyo University of Agriculture and Technology showed (J. Am. Chem. Soc. 2009, 131, 12552) that an isopropenyl amide 6 could be hydroacylated with high ee. Gregory C. Fu of MIT observed (J. Am. Chem. Soc. 2009, 131, 14231) that nitromethane 9 could be added to the allenyl amide 8 to give 10, the product of γ-bond formation. Robert K. Boeckman Jr. of the University of Rochester devised (Organic Lett. 2009, 11, 4544) what appears to be a general protocol for the construction of alkylated ternary and quaternary centers: enantioselective hydroxymethylation of an aldehyde 11. In another approach to the construction of alkylated quaternary centers, Varinder K. Aggarwal of the University of Bristol demonstrated (Angew. Chem. Int. Ed. 2009, 48, 6289) that an enantiomerically enriched trifluoroborate salt 14 could be added to an aromatic aldehyde 15 with retention of absolute configuration. The salt 14 was prepared from the corresponding high ee secondary benzyl alcohol. Weinreb amides are versatile precursors to a variety of functional groups. Stephen G. Davies of the University of Oxford devised (Organic Lett. 2009, 11, 3254) a chiral Weinreb amide equivalent 17 that could be alkylated with high de. The minor diastereomer from the alkylation was readily separable by silica gel chromatography. Keiji Maruoka of Kyoto University established (Angew. Chem. Int. Ed. 2009, 48, 5014) that a chiral phase transfer catalyst was effective for the enantioselective alkylation of the alkynyl ester 19. Emmanuel Riguet of the Université de Reims Champagne-Ardenne developed (Tetrahedron Lett. 2009, 50, 4283) an improved catalyst for the enantioselective addition of malonate 22 to cyclohexenone 21.

Construction of Alkylated Stereogenic Centers

2013 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Phase Transfer ◽  
Conjugate Addition ◽  
Enantioselective Hydrogenation ◽  
Boronic Acids ◽  
National University ◽  
Cu Catalyst ◽  
Institute Of Technology ◽  
Enantioselective Alkylation ◽  
Seoul National University ◽  
The University

Andreas Pfaltz of the University of Basel and Keisuke Suzuki of the Tokyo Institute of Technology showed (Angew. Chem. Int. Ed. 2010, 49, 881) that the iodohydrin of 1 did not interfere with the enantioselective hydrogenation. J. R. Falck of UT Southwestern developed (J. Am. Chem. Soc. 2010, 132, 2424) a procedure for coupling arene boronic acids with a cyano triflate 3, readily available in high ee from the corresponding aldehyde. Anita R. Maguire of University College Cork devised (J. Am. Chem. Soc. 2010, 132, 1184) a Cu catalyst for the enantioselective C-H insertion cyclization of 5 to 6. Jin-Quan Yu of Scripps/La Jolla established (J. Am. Chem. Soc. 2010, 132, 460) a complementary enantioselective C-H functionalization protocol, converting the prochiral 7 into 8 in high ee. Xumu Zhang of Rutgers University effected (Angew. Chem. Int. Ed. 2010, 49, 4047) enantioselective branching hydroformylation of 9 to give 10. T. V. RajanBabu of Ohio State University established (J. Am. Chem. Soc. 2010, 132, 3295) the enantioselective hydrovinylation of a diene 11 to the diene 12. Gregory C. Fu extended (J. Am. Chem. Soc. 2010, 132, 1264, 5010) Ni-mediated cross-coupling, both with alkenyl and aryl nucleophiles, to the racemic bromoketone 13. Hyeung-geun Park and Sang-sup Jew of Seoul National University used (Organic Lett. 2010, 12 , 2826) their asymmetric phase transfer protocol to effect the enantioselective alkylation of the amide 15. Kyung Woon Jung of the University of Southern California showed (J. Org. Chem. 2010, 75, 95) that the oxidative Pd-mediated Heck coupling of arene boronic acids to 17 could be effected in high ee. Nicolai Cramer of ETH Zurich observed (J. Am. Chem. Soc. 2010, 132, 5340) high enantioinduction in the cleavage of the prochiral cyclobutanol 19. Alexandre Alexakis of the University of Geneva achieved (Organic Lett. 2010, 12, 1988) the long-sought goal of efficient enantioselective conjugate addition of a Grignard reagent to an unsaturated aldehyde 21. Professor Alexakis also established (Organic Lett. 2010, 12, 2770) conditions for enantioselective conjugate addition to a nitrodiene 23. This procedure worked equally well for β-alkynyl nitroalkenes.

A Study on the Rearrangement of Dialkyl 1-Aryl-1-hydroxymethylphosphonates to Benzyl Phosphates

2020 ◽  
Vol 24 (4) ◽  
pp. 465-471 ◽  
Author(s):  
Zita Rádai ◽  
Réka Szabó ◽  
Áron Szigetvári ◽  
Nóra Zsuzsa Kiss ◽  
Zoltán Mucsi ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Room Temperature ◽  
Phase Transfer ◽  
One Pot ◽  
Substrate Dependence ◽  
Triethylbenzylammonium Chloride ◽  
One Step ◽  
The Pudovik Reaction ◽  
The One ◽  
Solid Liquid

The phospha-Brook rearrangement of dialkyl 1-aryl-1-hydroxymethylphosphonates (HPs) to the corresponding benzyl phosphates (BPs) has been elaborated under solid-liquid phase transfer catalytic conditions. The best procedure involved the use of triethylbenzylammonium chloride as the catalyst and Cs2CO3 as the base in acetonitrile as the solvent at room temperature. The substrate dependence of the rearrangement has been studied, and the mechanism of the transformation under discussion was explored by quantum chemical calculations. The key intermediate is an oxaphosphirane. The one-pot version starting with the Pudovik reaction has also been developed. The conditions of this tandem transformation were the same, as those for the one-step HP→BP conversion.

The Role of Phase Transfer Catalysis in the Microwave-Assisted N-Benzylation of Amides, Imides and N-Heterocycles

2009 ◽  
Vol 6 (7) ◽  
pp. 529-534 ◽  
Author(s):  
Istvan Greiner ◽  
Fanni Sypaseuth ◽  
Alajos Grun ◽  
Eva Karsai ◽  
Gyorgy Keglevich
Keyword(s):  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Microwave Assisted
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