Carbon‐13 nuclear magnetic resonance spectra of ceveratrum alkaloids

Abstract

The 13C NMR speetra were determined and signals assigned to the various carbons of the alkamines veracevine, germine and zygacine derived from steroidal alkaloids of the ceveratrum class. Assignment of signals was aided by analysis of the partially relaxed spectrum of cevagenine 9,12,14-orthoacetate-3,16-diacetate.

Carbon-13 and Proton Nuclear Magnetic Resonance Spectra of Veratrum Alkaloids

“…Loss of the shielding environment provided by C-18 and other portions of the ß-face of the steroidal framework could be responsible for these differences. 13C-nmr data have been reported (8) for the cevanine alkaloids shinonomenine (6) and veraflorizine (7), both of which contain A, B, and C rings similar to the jerveratrum alkaloids. Whereas most of the 13C-nmr assignments to carbons of the A and B rings of these C-nor-D-homo steroidal alkaloids are nearly identical to those determined for cyclopamine and cycloposine, values assigned (8) to C-7 (~31 ppm) and C-8 (~39 ppm) of 6 and 7 are ~8 and 3.5 ppm upfield (Table 3).…”