Enantioselective Syntheses of syn- and anti-β-Hydroxyallylsilanes Via Allene Hydroboration-Aldehyde Allylboration Reactions
摘要:
The kinetic hydroboration of allenylsilane 5 with ((d)Ipc)(2)BH at -40 degrees C provides allylborane 9Z with >= 12:1 selectivity. When the hydroboration is performed at temperatures above -40 degrees C, 9Z isomerizes to the thermodynamically more stable allylborane 9E with >20:1 selectivity. Subsequent treatment of 9Z or 9E with aldehydes at -78 degrees C provides syn- or anti-beta-hydroxyallylsilanes, 7 or 8, respectively.
Enantioselective Syntheses of <i>syn</i>- and <i>anti</i>-β-Hydroxyallylsilanes Via Allene Hydroboration-Aldehyde Allylboration Reactions
作者:Ming Chen、William R. Roush
DOI:10.1021/ol200392u
日期:2011.4.15
The kinetic hydroboration of allenylsilane 5 with ((d)Ipc)(2)BH at -40 degrees C provides allylborane 9Z with >= 12:1 selectivity. When the hydroboration is performed at temperatures above -40 degrees C, 9Z isomerizes to the thermodynamically more stable allylborane 9E with >20:1 selectivity. Subsequent treatment of 9Z or 9E with aldehydes at -78 degrees C provides syn- or anti-beta-hydroxyallylsilanes, 7 or 8, respectively.