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

Abstract

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

How easy are the syntheses of allenes?

“…Ni(II) also worked well for this reaction, which coordinated to the triple carbon-carbon bond to facilitate the attack of nucleophiles. 156 In most cases, the CuI-mediated catalytic system afforded better yields than the corresponding palladium catalysis. The configuration of all products was E, except for butyl substituted substrates.…”