Abstract
The two regioisomeric 4-diazo-2,3,4,5-tetrahydrofuran-3-ones 6 and 7 were prepared via the common intermediate 2,3,4,5-tetrahydro-2,2-dimethyl-5,5-diphenylfuran-3-one (8). Diazo transfer with 2,4,6-triisopropylbenzenesulfonyl azide yielded 6, whereas 7 was obtained via oxidation of the monohydrazone 12, which was prepared selectively from tetrahydrofuran-3,4-dione 11. The crystal structures of 6 and 7 have been established by X-ray crystallography.