A simple conversion of [E]- into the isomeric [Z]-2-(1-substituted-1-alkenyl)-1,3,2-dioxaborinanes, providing a convenient stereospecific synthesis of both [E]- and [Z]-1,2-disubstituted vinyl bromides
作者:Herbert C. Brown、Narayan G. Bhat
DOI:10.1016/0040-4039(88)80005-4
日期:——
A highly stereo- and regioselective conversion of [E]- into [Z]-2-(1-substituted-l-alkenyl)-1,3,2-dioxaborinane has been achieved for the first time. Treatment of these boronic acid esters with bromine, followed by base, produces either [Z]- or [E]-disubstituted vinyl bromides in good yields (76–81%) and excellent stereochemical purities (> 99%). Replacement of boron moiety with bromine proceeds with
首次实现了[ E ]-到[ Z ] -2-(1-取代-1-烯基)-1,3,2-二氧杂硼烷的高度立体和区域选择性转化。用溴,然后用碱处理这些硼酸酯,可制得[ Z ]-或[ E ]-二取代的乙烯基溴化物,收率好(76-81%),立体化学纯度也好(> 99%)。用溴取代硼部分进行完全转化。