Synthesis of Dihydropyridin-4(1H)-ones via Wolff Rearrangement

Significance

Reported is the synthesis of dihydropyridin-4(1H)-ones 3 via the Wolff rearrangement of amino acid derived diazoketones 1. The starting materials are easily prepared from the ­corresponding amino acids (N-benzylglycine, N-methylalanine and N-methylleucine) in three steps. The cyclic enaminone products 3 are obtained in excellent yield and as a single diastereo­mer in all cases. Diazoketones derived from cyclic amino acids lead to bicyclic and tricyclic products. A simple 6-exo-dig mechanism is suggested since no racemization of the amino acid derived starting materials is observed.