Asymmetric Synthesis of trans--Lactams by a Kinugasa Reaction on Water

The asymmetric Kinugasa reaction was performed on pure water for the first time without the need for any organic co-solvents. In contrast to most asymmetric Kinugasa reactions, trans--lactams were obtained as the major products in good yields, enantioselectivities, and diastereoselectivities (up to 90% yield, 98% ee, and >99:1 d.r.). This reaction is atom-economical, environmentally friendly, and affords synthetically useful but challenging products.