Axisonitrile-3, axisothiocyanate-3 and axamide-3. Sesquiterpenes with a novel spiro[4,5]decane skeleton from the sponge Axinella cannabina

Axisonitrile-3 from the marine sponge Axinella cannabina has been shown, on the basis of chemical and spectral data and by single-crystal 3-dimensional X-ray diffraction study, to be 1. Axisonitrile-3 was found to be a sesquiterpene isonitrile with a novel carbon skeleton (“spiroaxane”). From the same sponge, axisothiocyanate-3 (2) and axamide-3 (3), closely related to 1, have been also isolated and their structures determined.