Semiempirical calculation of 13C nuclear magnetic resonance chemical shift of acyclic hydrocarbons. Aplication to the stereochemical analysis of steroideal side chains

GONZALEZ SIERRA, M.; BUSTOS, D.A.; RUVEDA, E.A.; OLIVIERI, A.C.; MARIANO GRASSELLI

CANADIAN JOURNAL OF CHEMISTRY

NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

Lugar: Otawa; Año: 1988 vol. 66 p. 71 - 75

0008-4042

A semiempirical approach for predicting 13C nuclear magnetic resonance chemical shifts of acyclic hydrocarbons has been adapted to a microcomputer program. A series of methyl and dimethyl substituted cholesterols has been studied using thisprogram, and the predicted shifts are in agreement with literature reports. Preferred conformations of the steroidal side chains have been also predicted and agree with previous studies. A simple rule for analyzing the trends in the chemical shift of the carbon C-20, which is sensitive to changes in the configuration at C-22, is also given, not only for hydrocarbon side chains but also for hydroxy substituted compounds.