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Solvent-controlled intramolecular [2 + 2] photocycloadditions of alpha-substituted enones.

ABSTRACT: The regio- and stereoselectivity of intramolecular [2 + 2] photocycloadditions of 2'-hydroxyenones are shown to be solvent-dependent. In the presence of aprotic solvents, 2'-hydroxyenones undergo photocycloadditions in a manner consistent with the presence of an intramolecular hydrogen bond between the carbonyl group and the tether's hydroxy functionality. In protic solvents, intermolecular interactions appear to disrupt the intramolecular hydrogen bond, providing products with complementary diastereoselectivity. If the facial accessibility of the alpha-tethered olefin is limited, the cycloadditions proceed to give head-to-tail or head-to-head regioisomers, depending on the nature of the solvent employed.

SUBMITTER: Ng SM

PROVIDER: S-EPMC2531221 | biostudies-literature | 2006 Jun

REPOSITORIES: biostudies-literature

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Solvent-controlled intramolecular [2 + 2] photocycloadditions of alpha-substituted enones.

Ng Stephanie M SM Bader Scott J SJ Snapper Marc L ML

Journal of the American Chemical Society 20060601 22

The regio- and stereoselectivity of intramolecular [2 + 2] photocycloadditions of 2'-hydroxyenones are shown to be solvent-dependent. In the presence of aprotic solvents, 2'-hydroxyenones undergo photocycloadditions in a manner consistent with the presence of an intramolecular hydrogen bond between the carbonyl group and the tether's hydroxy functionality. In protic solvents, intermolecular interactions appear to disrupt the intramolecular hydrogen bond, providing products with complementary dia ...[more]

PMID: 16734486

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