Preparation and photolysis of diaryl esters of acetylenedicarboxylic acid

Article abstract of DOI:10.1016/0040-4020(92)85017-9

Two diaryl acetylenedicarboxylates 1 a,b have been prepared in moderate yields by direct reaction of acetylenedicarboxylic acid with the corresponding phenols catalyzed by sulfuric or p-toluenesulfonic acids and also through acetylenedicarbonyl chloride. The accompanying by-products have been characterized. Attempted esterification using N,N'-dicyclohexylcarbodiimide as condensing agent gives an asymmetric ester amide 11a and a substituted uracil 12a. Photolysis of the aryl ester 1 a,b in benzene solution affords the benzocoumaran-3-ones 14 a,b. In the case of 1b, minor amounts of a polycyclic condensed 4-chromanone 17b have also been observed. These results show that the nature of the substituent attached at the β-position of the C ≡ C triple bond plays an important role in the cyclization of o-hydroxyaryl ethynyl ketones.