Cycloaddition of sodium azide to polarized ketene S,S- and S,N-acetals: synthesis of novel substituted triazole and tetrazole derivatives

Abstract

Thermal [3+2] cycloadditon of aroylketene dithioacetals 1a-e with sodium azide affords novel 4-aroyl-5-methylthio-1H-1,2,3-triazoles 3a-e. The corresponding S,N-acetals 5a-m derived from primary amines react with sodium azide through different pathway involving cyclization of initially formed imidoyl azide intermediates to give novel 1,5-disubstituted tetrazole 7a-m in good yields. The S,N-acetal 5n obtained from malononitrile, however, undergoes cycloaddition on one of the nitrile groups to give a tetrazole 8.