One-Step Annelation. A Convenient Method for the Preparation of Diols, Spirolactones, and Spiroethers from Lactones

Article abstract of DOI:10.1021/jo01298a016

1-(ω-Hydroxyalkyl)cyclopentanols and -cyclohexanols were prepared in one step in high yields from butane-1,4-diyl- and pentane-1,5-diylmagnesium dibromides and lactones in tetrahydrofuran.This method was found to be general and applicable to lactones of any size (β, γ, δ, and ε) and structure whether aliphatic, aromatic, bicyclic, or spirocyclic.Evidently important steric hindrance close to the carbonyl group prevents annelation and attack on the second nucleophilic center of the Grignard reagent.Furthermore, in the case of oxetan-2-one one obtains, in additionto the corresponding diol, products resulting from scission of the C-O bond.The diols by appropriate transformation afford new routes to spirolactones and spiroethers.