New nitrogenous sesquiterpenes based on alloaromadendrane and epi-eudesmane skeletons from the marine sponge Axinellacannabina

Abstract

Six new nitrogenous sesquiterpenes (1–6), which form two new isocyanide-isothiocyanate-formamide series, have been isolated from the marine sponge Axinellacannabina. The structure elucidation of these compounds is based upon spectral data, including 2D-nmr, and chemical interconversions. The complete assignment of all proton and carbon resonances in nmr spectra of axisonitrile-2 (7), an isonitrile previously isolated from the same source, is also reported, along with its complete relative stereochemistry.