A highly efficient synthesis of(Z)-1-aryl-2-silyl-1-stannylethenes and their conversion to(E)-2-arylethenyl-,(Z)-2-(2-pyridyl)ethenyl- and allenyl-silanes

摘要

A Pd(dba)2-P(OEt)3 combination allowed the silastannation of arylacetylenes,1-hexyne or propargyl alcohols with tributyl(trimethylsilyl)stannane to take place at room temperature,producing(Z)-2-silyl-1-stannyl-1-substituted ethenes in high yields.Novel silyl(stannyl)ethenes were fully characterized by 1H-,13C-,29Si- and 119Sn-NMR as well as infrared and mass analyses.Treatment of a series of(Z)-1-aryl-2-silyl-1-stannylethenes and(Z)-1-(3-pyridyl)-2-silyl-1-stannylethene with hydrochloric acid or hydroiodic acid in the presence of tetraethylammonium chloride(TEAC1)or tetrabutylammonium iodide(TBAI)led to the exclusive formation of(E)-trimethyl(2-arylethenyl)silanes with high stereoselectivity.A similar reaction of(Z)-1-(2-anisyl)-2-silyl-1-stannylethene also produced E-type trimethyl[2-(2-anisyl)ethenyl]silane,while(Z)-trimethyl [2-(2-pyridyl)ethenyl]silane was produced exclusively from(Z)-1-(2-pyridyl)-2-silyl-1-stannylethene.Protodestannylation of(Z)-1-[hydroxy(phenyl)methyl]-2-silyl-1-stannylethene with trifluoroacetic acid took place via the bete-elimination of hydroxystannane,providing trimefhyl(3-phenylpropa-1,2-dienyl)silane quite easily.The destannylation products were also fully characterized.