Synthesis of some new hydrazide-hydrazones related to isatin and its Mannich and Schiff bases

Abstract

The hydrazide-hydrazones 6a-d and 7a, b were obtained by treating isatin (1) or its Mannich base 2 with hydrazides incorporating piperidine, morpholine, and piperazine units. The reaction of 1 and 2 with hydrazides related to triazenes having piperidine, morpholine, and 1,2,3,4-tetrahydroisoquinoline moieties gave 12a-c and 13a-c. Treatment of 1 and 2 with iminodiacetohydrazide (14) and ethylenediamine tetraacetohydrazide (18) afforded 15-17 and 19a, b, respectively. The Mannich reaction of the Schiff base 20 with formaldehyde and the appropriate hydrazide or bis(hydrazide) gave 21a, b and 22a, b. The hydrazides related to Schiff bases 20 and 26 were used as precursors in synthesis of compounds incorporating two 2-oxoindoline units or formazan moiety.