Periselectivity Switch of Acylketenes in Cycloadditions with 1-Azadienes: Microwave-Assisted Diastereoselective Domino Three-Component Synthesis of alpha-Spiro-delta-lactams

International audienceThe microwave-assisted Wolff rearrangement of cyclic 2-diazo-1,3-diketones in the presence of primary amines and alpha,beta-unsaturated aldehydes provides a straightforward three-component stereoselective access to a variety of alpha-spiro-delta-lactams following an imination/Wolff rearrangement/[2 + 4] cycloaddition domino sequence. With aniline derivatives, a complementary aza-Wittig/Wolff rearrangement/[2 + 4] sequence was developed. These reactions feature an unprecedented reactivity of acylketenes as dienophiles in 6 pi electrocyclic processes