One-Step Spiroannelation. Synthesis of Spiro γ- and δ-Lactones

Article abstract of DOI:10.1021/jo00328a021

Carbocyclic acid anhydrides can be converted to spiro γ- and δ-lactones by addition of di-Grignard reagents in tetrahydrofuran solution.Five- and six-membered rings have been formed in one-step reactions.Possible mechanistic pathways for this reaction are discussed.The conversion of spirolactones to 1-(ω-hydroxyalkyl)cycloalkanols was accomplished by reduction with LAH to illustrate the versatility of these substances giving (after or upon treatment with tosyl chloride) the corresponding spiroethers.