Aminomethylation of Michael Acceptors: Complementary Radical and Polar Approaches Mediated by Dialkylzincs

Phtalimidomethyl iodide and substituted maleimidomethyl iodide were used as radical precursors in dialkylzinc‐mediated radical addition to diethyl fumarate. The reactions led stereoselectively to functionalized pyrrolizidines. The radical mechanism was supported by spin‐trapping experiments and rationalized by theoretical calculations. Radical additions, on the one hand, and carbozincation followed by transmetalation with copper(I), on the other, were shown to be complementary methods to achieve the formal aminomethylation of activated unsaturated compounds. Radical attack: Phtalimidomethyl iodide and diiodomaleimidomethyl iodide were used as radical precursors in the dialkylzinc‐mediated radical addition to diethyl fumarate (see scheme). The reactions led stereoselectively to functionalized pyrrolizidines. Radical additions and carbozincation followed by transmetalation with copper(I) were shown to be complementary methods to achieve the formal aminomethylation of Michael acceptors.