GROUP, TRANSFER ADDITION-REACTIONS OF METHYL(PHENYLSELENO)MALONONITRILE TO ALKENES

Results of a detailed study of group transfer additions of methyl(phen ylseleno)propanedinitrile (4) to a wide variety of alkenes are reporte d. For example, heating of 4 (60 degrees C) with 1-hexene and AIBN pro duces (2-(phenylseleno)-hexyl)methylpropanedinitrile in 97% yield. Rea gent 4 adds in high yields to monosubstituted styrenes, enol ethers, e nol acetates, enol sulfides, enamides, and enol imidazoles and carbazo les. Additions to many classes of 1,2-disubstituted alkenes also occur , and modest to good levels of 1,2-asymmetric induction are observed i n the selenium transfer step. Oxygen- and sulfur-substituted alkenes p roduce anti products, and N-substituted alkenes produce syn products. The proposed mechanism involves radical addition followed by phenylsel enium group transfer, and it is shown that radical additions to certai n classes of disubstituted alkenes can be reversible. Additions to tri substituted alkenes fair, probably because of this reversibility. Comp etition studies provide a relative reactivity scale of alkenes toward the electrophilic methylpropanedinitrile radical. Finally, a series of transformations serve to illustrate some synthetic possibilities for the products of these selenium transfer addition reactions.