Synthesis of γ-Butyrolactams by Photoinduced PhSe Group Transfer Radical Cyclization and Formal Synthesis of (±)-Isocynometrine with Diphenyldiselenide as Promoter
with high regioselectivity and stereoselectivity from N-alkenyl α-PhSe β-keto amides. Reaction outcomes were modulated by the steric effect of the substituents on the nitrogen atom of the cyclization precursors and the stereoelectronic effect of the substrates. Diphenyldiselenide, as an additive, was found to promote ring closure. The advantage of this strategy in natural product synthesis is demonstrated
Three contiguous stereocenters with syn–anti structure on the 3-(1-hydroxyalkyl)pyrrolidinone were constructed in one step with high yields and high diastereoselectivity by an Et2AlCl-catalyzed group transfer radical cyclization reaction from N-alkenyl-β-hydroxyalkanamides with 125-W UV lamp irradiation. The relative stereochemistry was confirmed by X-ray analysis.