Abstract
Following the previous report on the reaction of 1-styryl-3, 4-dihydroisoquinoline derivatives, as diene component of a C=C-C=N system, with maleic anhydride, a reaction of 1-cyclohexenyl-3, 4-dihydro-6, 7-dimethoxyisoquinoline, possessing a cyclohexenyl group in place of styryl, with maleic anhydride was carried out under practically identical conditions. A compound (IV), identical in analytical values with that anticipated, was isolated as its picrate. In order to establish its structure, Hofmann degradation of the methiodide of the substance obtained by reduction and saponification of (IV), was carried out. Repeated three degradations resulted in the liberation of trimethylamine to form a neutral substance. Such a fact confirms the benzoquinolizine structure of the product and thereby indicates that this is a regular reaction. It was concluded from the result of the present and the preceding experiments that the diene component of C=C-C=N system including the C=N bond in 1-2 positions of the 3, 4-dihydroisoquinoline compound can take part in the Diels-Alder type reaction.
