Chiral Silanes via Asymmetric Hydrosilylation with Catalytic CuH
作者:Bruce H. Lipshutz、Naoki Tanaka、Benjamin R. Taft、Ching-Tien Lee
DOI:10.1021/ol0529593
日期:2006.5.1
[reaction: see text] CuH-catalyzed asymmetric conjugate reduction of beta-silyl-alpha,beta-unsaturated esters has been developed. Using PMHS as a stoichiometric source of hydride and in situ generated CuH ligated by Solvias' JOSIPHOS analogue PPF-P(t-Bu)(2) leads to highly enantioselective 1,4-reductions.
Construction of Quaternary Stereogenic Centers via [2 + 2] Cycloaddition Reactions. Synthesis of Homochiral 4,4-Disubstituted 2-Azetidinones and Imine Substituent Effects on β-Lactam Formation
作者:Claudio Palomo、Jesus M. Aizpurua、Jesus M. García、Regina Galarza、Marta Legido、Raquel Urchegui、Pascual Román、Antonio Luque、Juan Server-Carrió、Anthony Linden
DOI:10.1021/jo962017z
日期:1997.4.1
A study on the asymmetric construction of quaternary stereogenic centers via [2 + 2] cycloadditionreaction of ketenes with ketimines is described. Reaction of achiral ketenes and chiral alpha-alkoxy ketone-derived imines resulted in formation of new beta-lactams as single diastereomers. The cycloaddition was extended to pyruvate imines, aralkyl ketone-derived imines, and dialkyl ketimines. In these