Labdanediol, 2. the major component of the neutral part of Cistus ladaniferus L, was transformed into 12-nor-ambreinolide, precursor of ambrox(R), in three steps with an overall yield of 70%. Molecular modelling techniques have been used to determine the stereochemistry of the byproducts of these reactions. The selenylation and elimination reactions of alpha and betalevantanolides, obtained from labdanediol, 2, were used to synthetise alpha and beta-levantenolides.
Catalytic Carbonylative Spirolactonization of Hydroxycyclopropanols
作者:Dexter C. Davis、Katherine L. Walker、Chunhua Hu、Richard N. Zare、Robert M. Waymouth、Mingji Dai
DOI:10.1021/jacs.6b06573
日期:2016.8.24
four steps, respectively. The hydroxycyclopropanol substrates are readily available in one step via a Kulinkovich reaction of the corresponding lactones. Mechanistic studies utilizing high-resolution electrospray ionization massspectrometry (ESI-MS) identified several keyintermediates in the catalytic cycle, as well as those related to catalyst decomposition and competitive pathways.
Two hitherto unknown diterpene lactones have been isolated from Turkish tobacco. Characterization studies show that these compounds, now called α- and β-levantenolides, are represented by I and II. The levantenolides differ only in being epimeric at C12, and are closely related to labdanolic acid.