dimethyl, diethyl and tetramethylene sulfides gave the corresponding sulfonium cyclopentadienylide. But the ylides from diisopropyl and di-t-butyl sulfides were unstable, and the reaction mixture gave the CH and CS insertion products of cyclopentadienylidene and olefin elimination products. Reaction of diazocyclopentadiene in ethers gave the CH insertion and some CO insertion products. For diethyl
[3-(Ethylthio)allyl]titanium reagent generated easily from allyl ethyl sulfides condensed with aldehydes to give erythro-β-hydroxy sulfides in highly regio- and stereoselective manner. In contrast, crotyl ethyl sulfide reacted with aldehydes affording δ-hydroxy vinyl sulfide exclusively. The substitution pattern of the starting sulfide can have a pronounced effect on the selectivity in this condensation reaction