Photomediated Functionalization and Carbon—Carbon Bond Formation in Unactivated Molecules. Part 1. The Photomediated Reaction of Alkynes with Cycloalkanes.

Abstract

Cyclopentane derivatives Q 0030Photomediated Functionalization and Carbon-Carbon Bond Formation in Unactivated Molecules. Part 1. The Photomediated Reaction of Alkynes with Cycloalkanes. -Cycloalkanes react with alkynes bearing electron-withdrawing groups in the presence of benzophenone as photomediator to give alkenes as a mixture of (E) and (Z) isomers. In the case of substrates (IIf)-(IIh), only partial isolation of the products becomes possible. The reaction of cycloalkanes with acetylenedicarboxylates is highly stereoselective forming the (Z) isomer preferentially. The resulting products undergo photochemical double bond migration at 254 nm. In the case of (VI), a double migration affords initially a cyclopentylidene intermediate and leads finally to the cyclopentene (VII). -(DOOHAN, R. A.; HANNAN, J. J.; GERAGHTY*, N. W. A.; Org. Biomol. Chem. 4 (2006) 5, 942-952; Chem. Dep., Natl. Univ. Ire., Galway, Ire.; Eng.) -S. Adam 30-067