Photochemistry of unsaturated lactones. 2. Photoannelation of 2-acetyl-3,4,4-trimethyl-2-buten-4-olide by terminal alkynes

The photochemical cycloaddition of 2-acetyl-3,4,4-trimethyl-2-buten-4-olide to 1-heptyne and 1-chloro-2-propyne was carried out. The reaction gives isomeric cycloadducts of the head to head and head to tail types. The influence of solvent on the directivity of the reaction was investigated. The possibility was shown of using the cycloadducts obtained in the synthesis of difficulty available polyfunctionally substituted butanolides and heterocyclic compounds containing a spirocyclobutene fragment.For Communication 1, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1315–1320, October, 1986.