Theoretical calculation of circular dichroic exciton-coupled spectra of ouabain 1,19,2',3',4'-pentanaphthoate and its analogs was executed by a combination of conformational analysis with molecular mechanics and quantum-chemical calculation. Most of the calculated CD spectra show good agreement with the corresponding experimental data, which suggests that the method may be generalized for applications to other conformationally flexible natural products. The CD calculation was then used to evaluate the plausibility of "fortuitous CD cancellation," which was observed in the microscale naphthoylation study of hypothalamic inhibitory factor, a presumed ouabain isomer from bovine hypothalamus.
Copyright 1999 Wiley-Liss, Inc.