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

Abstract

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.