Highly cis- and trans-selective alkyl radical addition to α-methylene-γ-phenyl-γ-butyrolactams

The 1,3-asymmetric induction in alkyl radical additions to α-methylene-γ-phenyl-γ-butyrolactams was investigated. The reactions of N-unsubstituted lactam using (Me3Si)3SiH under UV irradiation give cis-α,γ-disubstituted lactams, whereas reactions of N-pivaloyllactams using Et3B and Bu3SnH in the presence of Yb(OTf)3 give trans-α,γ-disubstituted lactams, both with high diastereoselectivities.