Organic letters

Highly regio-and stereoselective synthesis of (Z)-trisubstituted alkenes via propyne bromoboration and tandem Pd-catalyzed cross-coupling

C Wang, T Tobrman, Z Xu, E Negishi

Index: Wang, Chao; Tobrman, Tomas; Xu, Zhaoqing; Negishi, Ei-Ichi Organic Letters, 2009 , vol. 11, # 18 p. 4092 - 4095

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Citation Number: 52

Abstract

Contrary to all previous reports, bromoboration of propyne with BBr3 proceeds in≥ 98% syn- selectivity to produce (Z)-2-bromo-1-propenyldibromoborane (1). Although 1 is readily prone to stereoisomerization, it can be converted to the pinacolboronate (2) of≥ 98% isomeric purity by treatment with pinacol, which may then be subjected to Negishi coupling to give trisubstituted (Z)-alkenylpinacolboronates (3) containing various R groups in 73− 90% ...