Synthesis of novel coumarin and benzocoumarin derivatives and their biological and photophysical studies

Several derivatives of coumarin-3N-carboxamides (3-21) have been prepared via the reaction of the coumarin-3-carbonyl chloride (1) with a number of nucleophiles. Novel double-headed coumarin-3N-carboxamides (26-33) were also produced using the same method. The Pechmann-Duisberg reaction was applied to prepare new benzo[f]- benzo[h]coumarins and 4-(chloromethyl)-pyrano[3,2-c]coumarin-2-one (36-42). The reaction of 1-chloromethylbenzo[f]coumarins (36) with cyanide anion under different reaction conditions was also investigated in order to assess its suitability for nucleophilic substitution reactions as well as ring transformation products (43-49). Synthesis of 1-((benzo[d]thiazol-2-yl)methyl)-9-hydroxybenzo[f]coumarin (50) represented the first example of methylene bridge-head heterocycle-containing benzo[f]coumarin. Some of the newly prepared coumarins exhibited anti-bacterial activity against Gram Positive and Gram negative bacteria. Compound 36d was found to be active against all the screened bacteria. Photophysical studies were performed on selected fluorescent benzo[f - and benzo[h]coumarin and the quantum yields were also calculated. All new compounds were characterized by IR, MS, H-1 and 13C NMR, as well as elemental analysis.