Dimethyl Acetylenedicarboxylate in Reactions with Substituted 3‐(2‐aminophenyl)‐6‐R¹‐1,2,4‐triazin‐5‐(2H)‐ones: Structure and Properties of the Products

Abstract

The article describes unusual [5 + 1]‐cyclocondensations of dimethyl acetylenedicarboxylate (DMAD), in which this reagent uncharacteristically acts as a 1,1‐biselelectrophilic agent. Reactions of DMAD with 1,5‐bisnucleophilic 3‐(2‐aminophenyl)‐6‐R1‐1,2,4‐triazin‐5(2H)‐ones yielded triazinoquinazoline‐derived diesters. The latter was shown to react with nucleophiles: hydrazine cleaved the pyrimidine ring of the diesters to give anilines, while ester hydrolysis furnished corresponding carboxylic acids.

Tandem heterocyclization of 2‐(azolyl‐(azinyl‐))anilines as an efficient method for preparation of substituted pyrrolo[1,2‐a]azolo‐(azino‐)[c]quinazolines

“…The usage of carbonyl‐containing compounds and their synthetic equivalents (aldehydes, ketones, paraform, acetals, and aldehydo acids) as electrophiles allowed to obtain partially hydrogenated or spiro‐condensed analogues . Similar results, namely, formation of 6,7‐dihydro‐2 H ‐[1,2,4]triazino[2,3‐ c ]quinazolines, were observed in the reaction of substituted 3‐(2‐aminophenyl)‐6‐ R ‐1,2,4‐triazin‐5(2 H )‐ones with DMAD, whereas reaction of 3‐(2‐aminophenyl)‐6‐ R ‐1,2,4‐triazin‐5(2 H )‐ones with о‐formylbenzoic and opianic acid occurred as tandem formation of pyrimidine and isoindole fragments that yielded corresponding isoindolo[2,1‐ a ][1,2,4]triazino[2,3‐ c ]quinazolines . 4 a ‐Alkyl‐2‐ R ‐5,6‐dihydropyrrolo[1,2‐ a ][1,2,4]triazolo[1,5‐ c ]quinazolin‐7(4 aH )‐ones were described as compounds that reveal anti‐inflammatory activity .…”