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RING-CHAIN TAUTOMERISM IN THE PRODUCTS OF THE REACTION BETWEEN 5-SUBSTITUTED FURFURYLAMINES AND ANHYDRIDES OF α,β-UNSATURATED CARBOXYLIC ACIDS

Фёдор И. Зубков, Виктор Д. Голубев, Владимир П. Зайцев, Ольга В. Баханович, Евгения В. Никитина, Виктор Н. Хрусталёв, Ринат Р. Айсин, Татьяна В. Тимофеева, Роман А. Новиков, Алексей Васильевич Варламов
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Abstract


The reactions of 5-substituted furfurylamines with anhydrides of α,β-unsaturated carboxylic acids (acryloyl chloride and maleic anhydride) were studied. The first step of the reaction mechanism involved acylation of furfurylamine nitrogen atom, followed by a stereospecific, spontaneous intramolecular Diels–Alder reaction at the furan ring of the N-furfurylamide intermediates. When the starting materials were 5-alkyl-substituted furfurylamines, the expected 1-oxo-2,3,7,7a-hexahydro-1Н-3а,6-epoxyisoindoles or the corresponding 7carboxylic acids were obtained in up to 98% yields. The acylation of 5-aryl-substituted furfurylamines with maleic anhydride led to N-furfurylmaleic amides, which formed a dynamic equilibrium in solutions with adducts formed by intramolecular [4+2] cycloaddition, 3а,6-epoxyisoindole-7-carboxylic acids, as proved by NMR spectroscopy. X-ray structural analysis results show that these mixtures crystallized in the form of the cyclic tautomer.

Authors: Fedor I. Zubkov*, Victor D. Golubev, Vladimir P. Zaytsev, Olga V. Bakhanovich, Evgeniya V. Nikitina, Victor N. Khrustalev, Rinat R. Aysin, Tatiana V. Timofeeva, Roman A. Novikov, Aleksey V. Varlamov


Keywords


furan; isoindole; [4+2] cycloaddition; dynamic stereochemistry; intramolecular Diels–Alder reaction; ring-chain tautomerism

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