RADICAL-ADDITION REACTIONS OF 2-(PHENYLSELENO)PROPANEDIOATES TO ALKENES AND ALKYNES

Sunlamp photolysis of methyl or ethyl 2-(phenylseleno)propanedioate with a variety of alkenes and alkynes in benzene yielded addition products in good to excellent yields. The proposed mechanism involves a radical chain process in which addition of a malonate ester radical is followed by phenylseleno transfer. Monosubstituted alkenes,l,l-and l,2-disubstituted alkenes, terminal alkynes, and internal alkynes were shown to undergo this reaction. Addition to diallyl ether led to substituted tetrahydrofurans, characteristic of a process involving initial addition, followed by cyclization prior to phenylseleno transfer. Vinyl arenes, conjugated dienes, and unsaturated carbonyl compounds proved unreactive.