Refluxing of 4-chlorocoumarin-3-carbonitrile, heteroarylamines (3-aminopyrazole, 3-aminopyrazole-4carbonitrile, 3-amino-l,2,4-triazole-5-thiol, 2-amino-6-fluorobenzothiazole, 2-amino-pyridin-3-ol, 1aminoisoquinoline) and the catalytic amount of trimethylamine in acetonitrile gave the corresponding 3,4annelated coumarins 1.-6 in high yields. The spectral analysis showed that 7-amino-5-oxa-7a,8,lltriazacyclopenta[Z>]phenantren-6-one (1) existed as enamine, 2 as a mixture of enamine 7-amino-6-oxo-5-oxa-7a,8,l l-triazacyclopenta[6]phenantren-10-carbonitrile (2a) and imine 7-imino-6-oxo-7//,8//-5-oxa-7a,8,l 1triazacyclopenta[6]phenantren-10-carbonitrile (2b). whereas 10-fluoro-7-imino-7//-5-oxo-12-thia-7a, 13diazaindeno[l,2-£>]phenantren-6-one (4), 1 l-hydroxy-7-imino-7//-7a, 12-diazabenzo[a]anthracen-6-one (5) and 7-imino-7//-5-oxa-7a,14-diazadibenzo[a,/i]anthracen-6-on (6) took imino forms.Synthesis and structure of some 3,4-annelated coumarin systems 7.40 (t, 1H) and 7.45 (t, 1H) (H-2 and H-4) ppm. C14H7N5O2 (252.2): calcd. C 60.63, Η 2.54, Ν 25.26; found C 60 72, Η 2.57, Ν 25.36.