RITTER REACTIONS - XIII REACTIVITY OF METHYL SCHIFF-BASES WITH DIMETHYL ACETYLENEDICARBOXYLATE AND MERCAPTOACETIC ACID

Reactions of several methyl imines with dimethyl acetylenedicarboxylat e and with mercaptoacetic acid have been studied to investigate furthe r the capricious behaviour of this functionality. The 1:1 adduct of im ine (1) and dimethyl acetylenedicarboxylate is confirmed as the pyrrol oisoquinoline structure (7) by X-ray methods [C17H17NO5, P (1) over ba r, a 9.037(2), b 9.276(2), c 10.033(2) Angstrom, alpha 81.99(1), beta 81.28(1), gamma 64.99(2)degrees, Z 2, R 0.044]. New products from (2) and dimethyl acetylenedicarboxylate, the 1:1 adduct (10) which is read ily converted into the known product (9), and the 1:2 adduct (12), are described. The structure of the last compound, which arises through a rearrangement process, was determined by X-ray crystallography [C27H3 6N2O9, Pca2(1), a 19.083(4), b 15.217(3), c 9.669(2) Angstrom, Z 4, R 0.038]. Methyl imines (1) and (4) undergo cyclocondensation with merca ptoacetic acid yielding thiazolidinone products but others are inert u nder similar conditions.