In the presence of a photomediator such as benzophenone, alkynes with electron-withdrawing groups react with cycloalkanes to give vinyl cycloalkanes. The reaction involves the regiospecific addition of a photochemically generated cycloalkyl radical to the beta-carbon of the alkyne. The stereochemical outcome of the reaction depends on the nature of the photomediator and alkyne used.

No abstract

No abstract

2001 photochemistry, radiation chemistry, chemoluminescence photochemistry, radiation chemistry, chemoluminescence O 0160 30 -057 Functionalization of Cycloalkanes: The Photomediated Reaction of Cycloalkanes with Alkynes. -In the presence of a photomediator, cycloalkanes are functionalized by photolytic C-H insertion of electron-deficient alkynes. -(GERAGHTY, NIALL W. A.; HANNAN, JOHN J.; Tetrahedron Lett. 42 (2001) 18, 3211-3213; Chem. Dep., Natl. Univ. Ire., Galway, Ire.; EN)

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