Indolizines. Part IV. Syntheses from 2-acylmethylene-1-benzyl-1,2-dihydropyridine, phenyl-2-picolyl sulphone, and related compounds

Abstract

The scope of a new route to indolizines, which involves ring-closure at the 2,-3 positions, has been investigated. In this method suitable 2-acyl- and 2-ethoxycarbonylmethylene-1-benzyl-1,2-dihydropyridines are cyclised to 2-acetoxy-3-aryl-, 2,3-diaryl-, and 2-alkyl-3-aryl-1-acetylindolizines by the action of acetic anhydride. Preparations of 1-amino- and 1-aminomethyl-indolizines have been continued. Indolizinyl sulphones have been synthesised from phenyl 2-picolyl sulphone.