| Abstract: | For the first time, oxacyclic ketones and -diketones are reacted with diazoacetic ester in the presence of a Lewis acid. It is found that 2,2, 5, 5-tetramethylfuranid-3-one(I) and 2, 2, 5, 5-tetramethylfuranidine-3, 4-dione (IV) undergo ring enlargement between the third and fourth carbon atoms in the ring, to give, respectively, 4-ethoxycarbonyl-2,2, 6, 6-tetramethyltetrahydropyrone-3 (II) and 4-ethoxycarbonyl-2, 2, 6, 6-tetramethyltetrahydropyran-3, 5-dione (V), with the characteristic properties of ß-ketoesters.For Part III see [17]. |
