Addition of 1,8-diaminonaphthalene1 to dimethylacetylene dicarboxylate (DMAD) leads to the perimidine4a and the naphthodiazepine3a. A similar reaction with the diethyl ester (DEAD) gave rise to3b and4b. The latter product has been incorrectly formulated as naphthodiazepine2b in the literature. 1,8-Dihydroxynaphthalene8 and DMAD gives rise to the naphthodioxane9, which is hydrolysed to the diacid11. 8-Hydroxy-1,2,3,4-tetrahydroquinoline (14) and acetylenic esters form pyridobenzoxazines15, which exist as equilibrium mixture of15 and16 in solution. The ethyl ester is hydrogenated to the dihydroderivative18b.1H and more particularly13C NMR spectra are used to assign structures to various products.
Volume 134, 2022
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