含窒素共軛系ジエンに関するDiels-Alder反応 (第1報)

1-Styryl-6,7-dimethoxy-3,4-dihydroisoquinolineと無水マレイン酸の反応

抄録

The Diels-Alder reactions reported to date chiefly used C=C-C=C system as the diene component and the use of C=C-C=N or N=C-C=N system was extremely rare. The present series of experiments were carrid out in order to see how far the nitrogen-containing conjugated diene system would submit to this reaction and, becuase, if C=C-C=N system diene synthesis was possible in 1-vinyl-3, 4-dihydroisoquinoline derivatives, it would contribute much to the synthesis of benzoquinolizine compounds, important as the basic structure of numerous alkaloids.
The synthesis of 1-vinyl derivative of isoquinoline seemed somewhat difficult that 1-styryl derivative, which can be prepared easily, was chosen. Its reaction with maleic anhydride was carried out and the reduction and decarboxylation of its reaction product afforded 1, 2, 3, 4, 6, 7-hexahydro-9, 10-dimethoxy-2-phenyl-11bH-benzo[α]-quinolizine, whose structure was confirmed by the identity of its infrared absorption spectrum with that of the authentic specimen synthesized by another route. Although the yield of this product is still not satisfactory as yet, it is certain that the desired objective had been attained.