New one-step process for the synthesis of functionalized 1,6-dioxaspiro[4,5]decanes

Article abstract of DOI:10.1016/0040-4020(95)00453-F

β-Phenylsulfonyl dihydrofurans 1 were readily prepared by reduction of α-phenylsulfonyl-γ-lactones with DIBAL-H, followed by dehydration with MsCl-Et₃N. Dihydrofurans 1 were deprotonated with n-BuLi and the resulting α-lithiated carbanion reacted with a wide variety of electrophiles. Particularly interesting is its reaction with γ-lactones because it affords 1,6-dioxaspiro[4,5]decanes in good yields in one-step procedure. This new method of synthesis of spiroketals, in non-acid conditions, is thermodynamically controlled and occurs with high stereoselectivity at C-4, C-5 and C-7, but not at C-2.