Michael Addition of Stannyl Ketone Enolate to α,β-Unsaturated Esters Catalyzed by Tetrabutylammonium Bromide and an ab Initio Theoretical Study of the Reaction Course
作者:Makoto Yasuda、Kouji Chiba、Noriyuki Ohigashi、Yasuhiro Katoh、Akio Baba
DOI:10.1021/ja028853+
日期:2003.6.1
Michael addition of stannyl ketone enolates to alpha,beta-unsaturated esters was accomplished in the presence of a catalytic amount of tetrabutylammonium bromide (Bu(4)NBr). Other typical systems using lithium enolate or silyl enolate with catalysts (TiCl(4) or Bu(4)NF) failed to give the desired products. The bromide anion from Bu(4)NBr coordinates to the tin center in enolate to accelerate the conjugate
Changing course with an additive: A striking example of the effect of TMSCl on lithium amide reactivity
作者:David C. Harrowven、Hon Suen Poon
DOI:10.1016/0040-4039(96)00817-9
日期:1996.6
When a solution of diethyl maleate and acetophenone is added to a cooled (−78°C) solution of a lithiumamide the maleate derivative 3 is given in good yield. Pre-treatment of the lithiumamide with TMSCl alters the course of this reaction dramatically. With half an equivalent of this additive the Michael adduct 4 is given in 62% yield while employing three equivalents leads to the silyl enol ether