Alkynyl Phenyl Selenides as Convenient Precursors for the Synthesis of Stereodefined Trisubstituted Alkenes

Article abstract of DOI:10.1016/0040-4020(95)00153-Y

The addition of p-toluenesulfonic acid to alkynyl phenyl selenides is regio- and stereospecific and affords (Z)-α-(phenylseleno)vinyl p-toluenesulfonates in good yield. α-(Phenylseleno)vinyl halides are obtained from the reactions of these compounds with magnesium halides.The reactions of (Z)-α-(phenylseleno)vinyl p-toluenesulfonates with cyanocuprates afford the corresponding trisubstituted alkenes in which the tosyl group has been selectively substituted by an aryl or an alkyl group with retention of configuration.Finally, the cross coupling reaction of these vinyl selenides with methylmagnesium bromide, in the presence of a nickel catalyst, occurs with retention of configuration and affords the selenium free trisubstituted alkenes.