Reactions of 4 or 3 .4-Disubstituted Coumarins With Nucleophilic Reagents

Reactions of 4-<>r 3,4-<lisubstituted-coumarins with nucleophilic reagents have been investigated. The reactions of 4-methoxy-coumarin with nucleophilic reagents were of limited success, however, 4-chloro-3-nitro-coumarin (III) with methanol, ethanol, benzyl alcohol or sodium acetate resulted in the formation of the corresponding 4-substituted-3-nitro-coumarins (Na-<l). 4-Alkoxyor chloro-3-nitro-coumarins (lYa, b or III) with benzyl mercaptan yielded 4-S-benzyl-3-nitro-coumarin (lYe) and 3,4-<li-S-benzyl-coumarin (VIII). Analogous reaction of 3-acetylarnin0-4-methoxy-coumarin with benzyl-mercaptan gave (X). Attempts to cyclise (X) to coumarino-thiazole resulted in the forma­tion of 3-<liacetylarnino derivative (XI). Reactions of the related 4-methoxy-6-methyl-2H-pyran-2-<>ne and its thio-analogue with benzylmercaptan afforded (XIIa) and (XIIb) respectively. 

P F G PRAILL ,A W KHAN ,M SIDDIQ ,