Heterocyclization of caprolactam hydrazidine by the action of 2,3-dioxopyrrolo[2,1-a]isoquinolines

Abstract

Keywords: 2-hydrazino-3,4,5,6-tetrahydro-2H-azepine, 2,3-dioxopyrrolo[2,1-a]isoquinolines, 3,3-dimethyl-1-(1,2,4-triazolo[4,5-a]azepan-8-ylcarbonylmethylideno)-1,2,3,4-tetrahydroisoquinolines, opening of the dioxopyrroline ring.In previous work [1, 2], we showed that the reaction of 2,3-dioxopyrrolo[2,1-a]isoquinolines with several dinucleophiles might proceed with opening of the lactam bond and concurrent heterocyclization. The reactions of these compounds with cyclic hydrazidines have not yet been reported. In a continuation of a study of the chemical properties of these compounds, we found that dioxopyrrolines 1a,1b readily undergo opening of the pyrroline ring upon moderate heating in benzene to give enamino ketones 2a,b.This method was used to synthesize various compounds with potential biological activity. In the case R = H, the compounds obtained are enamino ketones, which are capable of further transformations.The 1 H NMR spectra were taken on a Bruker-300 spectrometer at 300 MHz in CDCl 3 with HMDS as the internal standard. The IR spectra were taken on a Specord M-80 spectrometer for vaseline mulls. The electron impact mass spectra were taken on an MAT-311 at 70 eV.

Reactions of enamino keto esters of 1,2,3,4-tetrahydroisoquinoline series with nucleophiles

“…On interacting ester 2a with other hydrazides, such as cyanoacetylhydrazide and benzoic acid hydrazide in boiling glacial acetic acid or 2-propanol, no new products were isolated, which may be explained by the weak nucleophilic properties of the reactants used. It is known that 2,3-dioxopyrrolo[2,1-a]isoquinolines frequently play the role of acylating reagents, interacting with N-nucleophiles with opening of the pyrrole ring [4][5][6][7]. It therefore seemed of interest to study the acylation reaction of hydrazides with these reagents with the aim of obtaining substances analogous to compounds 5a,b in structure.…”

“…The mass spectrum of compound 3 contains a peak* for the molecular ion of 300 [M] + (27), and also a peak for the 3,3-dimethyl-1-methylidenecarbonyl-1,2,3,4-tetrahydroisoquinoline fragment at 200 (35), characteristic for compounds having this fragment in their structure [4][5][6][7]. In the mass spectrum of tricyclic ketone 4a a peak was observed for the molecular ion at 284 [M] + (12), and also a peak corresponding to cleavage of the semicarbazide fragment 211 [M] + (17).…”

Reaction of 2,3-dioxopyrrolo[2,1-a]iso-quinolines with binucleophiles

“…The use of o-aminothiophenol as the binucleophile in the reaction with dioxopyrrolines 1a-d leads to benzothiazole derivatives 2c-f. We have recently shown that dioxopyrroline ring opening occurs in the reaction of pyrroloisoquinoline 1a with caprolactam hydrazidine to give the bicyclic 1,2,4-triazolo[4,5-a]azepine system [6].…”