Thermische Umlagerung von Benzyl-1-alkinyl-äthern in Gegenwart von Aminen

Abstract

The benzyl-l-alkynyl ethers 1a and 1b in the presence of ammonia or diethylamine at 50 to 80° are transformed into the corresponding o-tolyl-acetamides 4 to 6 (scheme 1). This observation gives good evidence that benzyl-1-alkynyl ethers 1 rearrange by a [3,3] sigmatropic process to ketene intermediates 3 – as suggested by Arens et al. – which then react with the amine present. In the absence of ammonia and diethylamine, respectively, 3 yield 2-indanones 2 (scheme 1).