Asymmetric synthesis and fragmentation reactions of 2-alkyl- and 2, 4-dialkyl-3-iodo-1-oxocyclohexan-2, 4-carbolactones. Single enantiomer preparation of Δα, β-butenolides, 2-alkyl-4-hydroxy-2-cyclohexen-1-ones and butyrolactones

Fragmentation reactions of keto iodolactones 4 provide access to butenolides 5, 2-alkyl-4-hydroxy-2-cyclohexen-1-ones 6, and butyrolactones 9. Delta(alpha,beta)-Butenolides 5e and 5f were converted to heterocycles 14-16 by way of intramolecular cycloaddition reactions. (C) 1998 Elsevier Science Ltd. All rights reserved.