Ammonia-Promoted Fragmentation of 2-Alkyl- and 2,4-Dialkyl-3-iodo-1- oxocyclohexan-2,4-carbolactones

2-Alkyl- and 2,4-dialkyl-3-iodo-1-oxocyclohexan-2,4-carbolactones undergo ammonia-promoted fragmentation reactions to provide butenolides, γ-butyrolactone, and/or β,γ-epoxycyclohexanones. Product distribution is governed by
the relative size of the substituents at C-2 and C-4 of the
cyclohexanones. Butenolide amide, the major product from
the fragmentation, is further converted into their respective
piperidinone and pyrrolidine derivatives.