E- and Z-β-formylvinyl synthons from 1-tributylstannyl-3,3-diethoxy-prop-1-ene via cross coupling with acid chlorides
摘要:
The easily prepared and stored E-1-tributylstannyl-3,3-diethoxy-prop-1-ene 1E reacts with acyl chlorides in DMF in the presence of PdCl2(MeCN)2 to give the expected 1,4-ketoacetals (E isomers). Similarly cross coupling of 1E with tosyl chloride performed in THF in the presence of Pd(PPh3)4 affords the E-beta-diethoxymethylvinylsulphone whose metallation with MeLi, LiBr generates a beta-formylvinylanion equivalent with the anionic centre in a cis relationship relative to the diethoxymethyl group.