Abstract
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Several derivatives of coumarin‐3__N__‐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‐3__N__‐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 heterocyclecontaining 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, ^1^H and ^13^C NMR, as well as elemental analysis.