Carbon-13 nuclear magnetic resonance spectra of pterosin-sesquiterpenes and related indan-1-one derivatives.

Methyl derivatives of indan-1-one were prepared as models to aid in interpreting the carbon-13 nuclear magnetic resonance (13C-NMR) spectra of pterosin-sesquiterpenes which were isolated from bracken fern, Pteridium aquilinum var. latiusculum. The chemical shifts of the carbons of the methylindan-1-ones were assigned by the proton decoupling technique. All the 13C-NMR signals of the pterosin-sesquiterpenes were assigned by means of selective proton decouplings, and from the 13C-1H long-range couplings and 13C chemical shifts of the model compounds..