Abstract
The structure of ketodihydrocampholenolactone (II), which had been obtained by oxidation of dihydrocampholenolactone (I) (1, 8, 8-trimethyl-2-oxabicyclo [3, 3, 0] octan-3-one) and called by Fujita, was established to be the formula of 1, 8, 8-trimethyl-2-oxabicyclo [3, 3, 0] octan-3, 6-dione (III).