The action of benzoyl chloride and pyridine on 5-hydroxy-6-acetyl-4-methylcoumarin and reactions related thereto

Abstract

5-Hydroxy-6-acetyl-4-methylcomarin (I) with bezol chloride and pyridene in the cold gives the 5- benzoate (II) ; R = Ph) which can be transformed into the 5-hydroxy-diketone (III; R = Ph) by an intramolecular Claisen condensation. Both these products can be cyclized to 2'-phenyl-4-methylechromono (7' : 8'-6:5)pyr-2-one (VI : R = Ph0, previously (Shah and Deliwala, proc. Indian Acad, Sci., 1942, 16,387) obtained by the direct action of benzol chloride in boiling pyridine on (I). The 5-hydroxy-diketone is probably not an intermediate, as postulated by Shah and Deliwala, in this direct formulation of (IV) from (I), since benzol chloride and pyridene intrroduce a further benzol group to yield 3'-benzoyl-2' phenyl-4-methylchromono(7' : 8'-6 : 5)pyr-2-one (V: R = R' = Ph). This 3'-benzoyl derivative is also formed by the action of pyride alone on a mixture of the 5-benzoate (II) and 5-hydroxy-diketone (III). Several analogous reactions are effected with other aroyl chloride.