Novel synthesis of 3H-pyrroles, and novel intermediates in the Paal–Knorr 1H-pyrrole synthesis: 2-hydroxy-3,4-dihydro-2H-pyrroles from 1,4-diketones and liquid ammonia

Abstract

Reaction of 2,2-dimethyl-1,4-diketones with liquid ammonia gives high yields of isolable 2-hydroxy-3,4-dihydro-2H-pyrroles (3) and (5) which are readily dehydrated to give separable mixtures of 3H-pyrroles and methylenedihydropyrroles, while less-substituted 1,4-diketones give analogous hydroxy-compounds (4) and (6) which are hitherto-unsuspected intermediates in the Paal–Knorr 1H-pyrrole synthesis.