An efficient efficient preparation of 1,2-dihydropyridazines through a Diels-Alder/palladium-catalysed elimination sequence

A convenient, scalable synthesis of 1,2-dihydropyridazines is presented, based on the Diels-Alder cycloaddition of 1-acetoxy-1,3-butadiene with a variety of azo compounds, followed by a palladium-catalysed elimination. The products are produced on multigram scale and the new method is particularly efficient and atom-economical when compared with previous preparations of 1,2-dihydropyridazines. (C) 2019 Elsevier Ltd. All rights reserved.