Tetrahydrofurane und γ‐Lactone, VII. Synthese und Reaktionen von γ,γ‐disubstituierten γ‐Lactonen – ein Weg zu funktionalisierten Dodecandisäure‐Derivaten

Tetrahydrofurans and γ‐Lactones, VII. – Synthesis and Reactions of γ,γ‐Disubstituted γ‐Lactones – an Approach to 4,5‐Functionalized Dodecanedioic Acid Derivatives The title compounds 5 are obtained by Diels‐Alder reaction of cyclooctyne and 2‐substituted furans, subsequent hydrogenation, ozonolysis and oxidation with air. The lactone ring of 6c is opened by treatment with sodium iodide and zinc to give the methylene carbonyl derivative 9a. Compound 9a is converted into the cyclopropane 13 via the pyrazoline 12. magnified image