The reactions of 2-alkynylbenzaldehydes with hydrazides: a route to isoquinoline N-imines

Abstract

Sulphonyl-and acyl-hydrazones of 2-ethynylbenzaldehyde cyclise in the presence of base to give isoquinoline N-imines in moderate yield. The suggested mechanism involves primary formation of the hydrazone anion followed by nucleophilic attack on the alkyne bond, either by the anionic nitrogen to give an unstable 3H-2,3-benzodiazepine which rearranges to the isoquinoline N-imine, or by the neutral imine nitrogen to give the isoquinoline system directly. Attempts to extend the reaction to the semicarbazone and 2,4-dinitrophenylhydrazone were not successful.

Generation of Polyfluoroaryl‐Fused H‐Pyrazolo[5,1‐a]isoquinolines through a Reaction of N′‐(2‐Alkynylbenzylidene)hydrazide with Polyfluoroarene

“…HRMS spectra were obtained on a micrOTOF II instrument. N ′‐(2‐Alkynylbenzylidene)hydrazide was synthesized according to the literature method by condensation of 2‐alkynylbenzaldehyde with hydrazine 8…”

“…N'-(2-Alkynylbenzylidene)hydrazide was synthesized according to the literature method by condensation of 2-alkynylbenzaldehyde with hydrazine. [8] General Experimental Procedure for the Generation of Polyfluoroaryl-…”

Integrated Chemical Process: One-Pot Double Elimination Method for Acetylenes

“…The crude mixture was subjected to column chromatography to give 3 cc [9] in 88 % yield. [24] Compound 3cb: …”

Synthesis of Heterocycles and Carbocycles by Electrophilic Cyclization of Alkynes

“…80 Quinoline derivatives have been prepared by the base-promoted cyclization of 2-(1-alkynyl)benzaldehyde oximes [176] and hydrazones [177] (Equation 2.132).…”