Influence des substituants sur la vitesse de racémisation des cétones à carbone dissymétrique en alpha
作者:A. K. Mills、A. E. Wilder Smith
DOI:10.1002/hlca.19600430705
日期:——
The rates of racemisation, under constant conditions of pH and temperature, of two series of ketones with an asymmetric C-atom in α have been determined. As would be expected, substituents in the α position to the keto group influence the rate of racemisation, and it has been found possible to assess the relative electron donating or electron attracting effect of aliphatic, aliphatic-aromatic or aromatic
Chiral Bis(oxazolidine)pyridine–Copper-Catalyzed Enantioselective Friedel–Crafts Alkylation of Indoles with Nitroalkenes
作者:Takayoshi Arai、Toru Sato
DOI:10.1055/s-0033-1340311
日期:——
asymmetric Friedel–Crafts reaction of indoles with nitroalkenes was catalyzed by the stereochemically tunable bis(oxazolidine)pyridine (PyBodine)–Cu(OTf)2 complex. Using the PyBodine(Val)–Cu(OTf)2 catalyst gave the Friedel–Crafts adducts with highly enantioselective manner. For the 1,4-bis[(E)-2-nitrovinyl]benzene, the reaction proceeded in a meso-trick manner to give the chiral double Friedel–Crafts adduct
Highly Enantioselective Direct Aldol Reaction Catalyzed by Organic Molecules
作者:Monika Raj、Vishnumaya、Sandeep K. Ginotra、Vinod K. Singh
DOI:10.1021/ol0616081
日期:2006.8.1
compounds catalyzed the directaldolreaction between aldehydes and acetone to provide beta-hydroxy ketones in good yields. The reaction is efficient, and 5-10 mol % of the catalyst and excellent enantioselectivities (97-99% ee) were obtained in both aromatic and aliphatic aldehydes. The presence of a gem-diphenyl group at the beta-carbon is necessary for high enantioselectivity.
Enantioselective catalysis 94. The “diphenyl effect” in the enantioselective hydrosilylation of acetophenone with diphenylsilane using Rh/5,5-diphenyl-2-(2-pyridinyl)oxazoline catalysts
作者:Henri Brunner、Christopher Henrichs
DOI:10.1016/0957-4166(95)00052-q
日期:1995.3
The 5,5-diphenyl-2-(2-pyridinyl)oxazolines 2a-e give ee values 9.6 - 34.2 % higher than their unsubstituted counterparts 1a-e in the Rh-catalyzed enantioselective hydrosilylation of acetophenone with diphenylsilane.