Treatment of the cyclic diketones (I) or (IV) with NH4OAc (II) yields the acylpyrroles (III) or (V) via rearrangement.

Complete 13C NMR chemical shift assignments are reported for 32 cyclic and one acyclic 1,3‐diketones, either unsubstituted or having one or two substituents at the 2‐position. The first two classes exist exclusively in the enol form in (CD3)2SO and as mixed tautomers in CDCl3.

Reaction of 2,2-dimethyl-I ,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 1 H-pyrrole synthesis.

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Treatment of the carbonyl compounds (I), (IV), and (VII) with liquid ammonia yields the hydroxydihydropyrroles (II), (III), (V), (VIII), and (IX) and the pyrroles (VI) and (X).