4-Vinylbenzoic acid → 5-(4-vinylbenzoyl)-1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylic acid

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Reaktionsschritte

A solution of methyl 1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylate (Formula B where Y is hydrogen) the synthesis of which is described in Preparations 1 and 2 hereinabove, (3.0 g, 18 mmol) and the acid chloride of 4-vinylbenzoic acid [J. Chem. Education, 55, 813 (1978)] (10.0 g, 60 mmol) in anhydrous xylene (100 ml) was heated at reflux temperature for 6 hours. The solvent was removed in vacuo and the residue was purified by column chromatography on Act II neutral alumina (Fluka, 200 g). The product was eluted with hexane-ethyl acetate (95:5) to give 5-(4-vinylbenzoyl)-1,2-dihydro-3H-pyrrolo[1,2,a]pyrrole-1-carboxylic acid, (36%) which had mp 99°-100° after crystallization from methanol. The purified product exhibited the following characteristics:

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