Abstract
5, 9-Dimethyl-5, 6-dihydro- (or-5, 6, 8, 9-tetrahydro-) 4H-benzofuro- [5, 6, 7-de] isoquinoline-4, 6-dione (5a, 8a) were synthesized by the Claisen rearrangement of 4-allyloxynaphthal-N-methylimide. Similarly, 8-phenyl derivatives of (5a) and (8a), (5b, 8b) were obtained from 4-cinnamyloxynaphthal-N-methylimide. In addition to (8b), in the latter case, 5-methyl-8-phenyl-5, 6-dihydro-4 H, 10 H- [1] benzopyrano [6, 7, 8-de] isoquinoline-4, 6-dione (9) was formed as a by-product.
Furthermore, several 3-substituted-4-methoxynaphthal-N-methylimides [e. g. propenyl (11a), α-phenylpropenyl (11b), carboxy (12), methoxycarbonyl (13), carbamoyl (14) and benzoyl (16)] were derived from the 3-allyl- (10a) or 3-α-phenylallyl-4-methoxy derivative (10b). The fluorescence spectra of these compounds were determined and the relationship between their structures and spectra was discussed.
The results are as follows. 1) The annellated dihydrofuran ring (5a), (5b) causes a shift (30 mμ) to longer wavelength at the fluorescence maximum and a slight increase in the fluorescence intensity, compared with 4-methoxynaphthal-N-methylimide as the standard sample. 2) On the other hand, the annellated furan ring (8a) results in only 10mμ shift and its intensity falls to 1/10 of that of the standard sample. 3) Fluorescence intensities of (8b), (9), (11b) and (16) are too weak to be measured under the conditions probably due to the non-planarity between their phenyl group and the naphthalene nucleus.
