Ring-opening cyclization of spirocyclopropanes with stabilized sulfonium ylides for the construction of a chromane skeleton

Regioselective ring-opening cyclization of cyclohexane-1,3-dione-2-spirocyclopropanes with stabilized sulfonium ylides provided 2,3- trans -disubstituted 2,3,4,6,7,8-hexahydro-5 H -1-benzopyran-5-ones in high yields without the formation of any isomers. The obtained product was readily converted into highly substituted chromane. A regioselective ring-opening cyclization of spirocyclopropanes with sulfonium ylides afforded 2,3- trans -hexahydrobenzopyran-5-ones in high yields without the formation of any diastereoisomers.