Addition of RMgCl (R = n-Bu, Ph) to pinacol esters of 6-tosyloxy-1-alkenyl boronic acids at -78 degrees C gave the borates, which upon warming to room temperature underwent migration of R on boron to C(l) carbon and concomitant ring construction C-C bond formation between C(2) and C(6), eventually producing cyclopentyl alkyl (or aryl) carbinols after oxidative workup of the borane intermediates with 35% H2O2. Eight examples are presented and the reaction was applied to construction of a cyclohexyl carbinol.
PREPARATION OF SOME CYCLOPENTANE DERIVATIVES
作者:W. R. Edwards、E. Emmet Reid
DOI:10.1021/ja01371a032
日期:1930.8
Photoinduced Carboborative Ring Contraction Enables Regio- and Stereoselective Synthesis of Multiply Substituted Five-Membered Carbocycles and Heterocycles
作者:Shengfei Jin、Vu T. Nguyen、Hang T. Dang、Dat P. Nguyen、Hadi D. Arman、Oleg V. Larionov
DOI:10.1021/jacs.7b07128
日期:2017.8.23
herein a photoinduced carboborative ringcontraction of monounsaturated six-membered carbocycles and heterocycles. The reaction produces substituted five-membered ring systems stereoselectively and on preparative scales. The products feature multiple stereocenters, including contiguous quaternary carbons. We show that the reaction can serve as a synthetic platform for ring system alteration of natural products