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3-NITRO-2-PHENYL-2-TRIFLUOROMETHYL-2H-CHROMENES IN REACTIONS WITH AZOMETHINE YLIDES FROM ISATINS AND (THIA)PROLINE: SYNTHESIS OF SPIRO[CHROMENO(THIA)PYRROLIZIDINE-11,3'-OXINDOLES]

Игорь Б. Кутяшев, Иван A. Кочнев, Анастатсия A. Черепкова, Николай C. Зимницкий, Алексей Ю. Барков, Владислав Ю. Коротаев, Вячеслав Я. Сосновских
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Abstract


1,3-Dipolar cycloaddition of stabilized azomethine ylides generated in situ from isatins and proline to 3-nitro-2-phenyl-2-trifluoromethyl-2H-chromenes in i-PrOH proceeds stereoselectively at room temperature and leads to the formation of hexahydro-6H-spiro[chromeno[3,4-a]pyrrolizine-11,3'-indolin]-2'-ones with the cis arrangement of the trifluoromethyl group and the nitro group. A similar reaction with the participation of thiaproline-based ylides at 50°С leads to mixtures of diastereomeric tetrahydro-6H,9H-spiro[chromeno[3',4':3,4]pyrrolo[1,2-c]thiazole-11,3'-indolin]-2'-ones with a predominance of the cis- or trans-isomer. The stereochemistry of the obtained products was confirmed by the NOESY experiment and X-ray structural analysis.

Keywords


3-nitro-2-phenyl-2-trifluoromethyl-2H-chromenes; spiro[chromeno(thia)pyrrolizidine-11,3'-oxindoles]; 1,3-dipolar cycloaddition; stabilized azomethine ylides.

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