Reaction of acetylenic esters with 1,8-diaminonaphthalene, 1,8-dihydroxynaphthalene and 8-hydroxy-1,2,3,4-tetrahydroquinoline

Abstract

Addition of 1,8-diaminonaphthalene1 to dimethylacetylene dicarboxylate (DMAD) leads to the perimidine 4a and the naphthodiazepine 3a. A similar reaction with the diethyl ester (DEAD) gave rise to 3b and4b. The latter product has been incorrectly formulated as naphthodiazepine 2b in the literature. 1,8-Dihydroxynaphthalene 8 and DMAD gives rise to the naphthodioxane 9, which is hydrolysed to the diacid 11. 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 particularly ¹³C NMR spectra are used to assign structures to various products.