

SYNTHESIS AND STRUCTURE OF ESTERIFICATION PRODUCTS OF 6-ARYL-1,2,3,6,7,7а-HEXAHYDRO-3а,6-EPOXYISOINDOLE-7-CARBOXYLIC ACIDS

Abstract
It was found that the reaction of 5-arylfurfurilamines with maleic anhydride leads to the formation of 6-aryl-3a,6-epoxyisoindole-7-carboxylic acids (the cyclic form), which in solution are in dynamic equilibrium with N-furfurylmaleinamides (the open form). During the esterification of these tautomeric mixtures with methanol in the presence of a catalytic amount of sulfuric acid, methyl esters of 5-aryl-7a-hydroxy-7-methoxy-3-oxo-2,3,3a,4,7,7a-hexahydro-1H-isoindole-4-carboxylic acids, unexpected cleavage products of the 3a,6-oxobridge of the cyclic form, are formed diastereospecifically. The structure of the obtained products was confirmed by X-ray structural analysis.
Keywords
furan; isoindole; 7-oxabicyclo[2.2.1]heptene; [4+2] cycloaddition; esterification; IMDAF reaction; intramolecular Diels– Alder reaction.
Latvian Institute of Organic Synthesis - Aizkraukles iela, 21, Riga, LV-1006, Latvia - hgs@osi.lv