Stereospecific synthesis of a family of novel (E)-2-aryl-1-silylalka-1,4-dienes or (E)-4-aryl-5-silyipenta-1,2,4-trienes via a cross-coupling of (Z)-silyl(stannyl)ethenes with allyl halides or propargyl bromide

Stereospecific synthesis of a family of novel (E)-2-aryl-1-silylalka-1,4-dienes or (E)-4-aryl-5-silyipenta-1,2,4-trienes via a cross-coupling of (Z)-silyl(stannyl)ethenes with allyl halides or propargyl bromide is described. In the reaction with allyl bromide, either a Pd(dba)(2)-Cul combination (dba, dibenzylideneacetone) in DMF or copper(l) iodide in DMSO-THF readily catalyzes or mediates the coupling reaction of (Z)-silyi(stannyl)ethenes at room temperature, producing novel vinylsilanes bearing an allyl group beta to silicon with cis-disposition in good yields. Allyl chlorides as halides can be used in the Cul-mediated reaction. Cul alone much more effectively mediates the cross-coupling reaction with propargyl bromide in DMSO-THIF at room temperature compared with a Pd(dba)(2)-Cul combination catalysis in DMF, providing novel stereodefined vinylsilanes bearing an allenyl group beta to silicon with cis-disposition in good yields. Copyright (c) 2008 John Wiley & Sons, Ltd.