TANDEM SEQUENCE OF ARSCL INITIATED AD(E) REACTIONS RESULTING IN FORMATION OF 2 C-C BONDS

A one-pot procedure for the sequence of reactions between arylsulfanyl chloride, vinyl ether-I, vinyl ether-II and organomagnesium reagents has been developed for assembling polyfunctional compounds from simple precursors. 2,3-Dihydropyran and various vinyl ethers have been used as VE-I and/or VE-II. The dependence of the stereochemical course of t he carbon-carbon bond formation step upon the Lewis acid has been stud ied. In the case of the sequence p-tolylsulfanyl chloride, 2,3-dihydro pyran, 1-methoxy-2-methylpropene and Grignard reagent the reaction ini tiated with TiCl4 takes place with a very high diastereoselectivity (> 95%).