Esters, Paterno-Biichi reaction

Photoaddition of carboxylate esters to diphenylacetylene has also been reported. For example, irradiation of methyl p-cyanobenzoate and diphenylacetylene gave in 86% overall yield the enol ether (71), presumably a result of carbonyl n,tt triplet addition to the alkyne to form the unstable oxetene, which r idly ring opens. This complements the utility of aromatic esters in the Paterno-Biichi reaction with al-kenes as discussed by Cantrell. - ... 

The following tables contain a representative survey of inter- and intramolecular Paterno-Biichi reactions with the emphasis on cycloadditions of aldehydes (Tables 9 and 14) and ketones (Tables 10 and 14). In addition, examples of cycloadditions of 1,2-diketones, a-oxocarboxylic esters, simple esters, and imides are presented in Tables 11 -13. The formation of side products and further transformations to consecutive products are denoted when possible. 

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