Depending upon the conditions, heating of 1,10a-dihydro-2H,5H-pyrrolo-[1,2-b]isoquinoline-3,10-diones in polyphosphoric or hydrochloric acid gives rise to hydride transfer and oxidative processes. Mono or dienyl lactams, or mixtures of dimers and acids or hydroxyacids of the isoquinotine series were thus formed. Procedures leading specifically to each of these products have been found.

During attempted Friedel–Crafts cyclization of some arylmethyl pyroglutamic acids or of N-phenacyl prolines, decomposition of the activated form of the acid have been observed, giving new heterocyclic systems. This general decarboxylation occurred when there are difficulties to realize a Friedel–Crafts cyclization and is explained by geometrical or electronic considerations.

Reduction of substituted benzophenones 1 with sodium borohydride and trifluoro-acetic acid yields diphenylmethanes 3 as well as dimers 5 and 6. The complete structure of these substituted diphenylmethane dimers 5 may be accurately determined by H-1, C-13, 2D NMR analysis, and a mechanism for their formation is suggested.

Vinylogs of N-acyl N,O-acetals are formed in good yields by anodic oxidation, in methanol or water, of β-enaminoesters derived from pyroglutamic acid. These new acetals react easily with nucleophiles or silylated amines.