Direct Reduction of Allylic Alcohols Using Isopropanol as Reductant
作者:Masahiro Sai
DOI:10.1002/adsc.201800731
日期:2018.9.17
lithium cation‐catalyzed direct reduction of allylicalcohols to alkenes using isopropanol as a hydride donor was developed. The hydride transfer of the in situ‐generated lithium isopropoxide to an allylic cation is the key process in this transformation. The reaction generates only water and acetone as byproducts, which highlights the synthetic utility of this method.
Tetraorganoindium atecomplexes, prepared by the addition of organolithium reagents to trialkylindium, reacted with α,β-unsaturated ketones in a 1,4-addition fashion; allylic indates derived from allylic indium sesquihalides coupled with allylichalides regio- and stereo-specifically to give high yields of head-to-tail 1,5-dienes.
An efficient reductive Claisen rearrangement, catalyzed by in situ generated copper hydride and stoichiometric in diethoxymethylsilane, has been developed. Yields of up to 95 % with good to excellent diastereoselectivities were observed in this reaction. Mechanistic studies showed that the stereospecific rearrangement proceeded via a chair transition state of (E)‐silyl ketene acetals as intermediates