Sterolic and triterpenoidic constituents of stem bark of Drypetes gossweileri.

Four compounds have been identified from the stem bark of Drypetes gossweileri by means of 1H- and 13C-NMR spectroscopy, stearic acid, methyl putranjate, and two new compounds: stigmasterol stearate and beta-sitosterol stearate.

[Application of artificial intelligence techniques in organic chemistry. Study, by computer, of NMR 13C of steroids]. / Aplicações de técnicas de inteligência artificial em química orgânica. Estudo, por computador, de RMN 13C de esteróides.

This work describes the utilization of two groups of programs in searching for characteristic signals of NMR 13C of steroidal compounds. The first group of programs used data bases with the spectral data and a methodology that enables the choice and the search of substructures. The chemical shifts and multiplicities for each specific substructure are used as rules to identify different types and subtypes of steroidal compounds. The second one was built to apply the rules formulated by the first group of programs and to foresee any skeletal based on a spectral analysis.