0000000000951273
AUTHOR
Maria J. Gil-gimeno
(-)-(5S,8S,9R,10S,13R,14R)-15,16-Dideoxy-16,17-epoxy-16-oxospongian-15-yl acetate.
The title compound (aplyroseol-14), C22H34O4, exhibits a lactone-based structure that is novel for spongian-type diterpenoids. The structure, which features a six-membered lactone ring, was proposed by Arno, Gonzalez & Zaragoza [J. Org. Chem. (2003), 68, 1242–1251] on the basis of spectroscopic data and chemical correlations. This assignment has been confirmed, and it is shown that the molecule contains a trans–anti–trans 6/6/6 tricyclic hydrocarbon system and that the acetoxymethyl group lies in an equatorial position. Pairs of near-linear C—H⋯O interactions link molecules into extended chains.
Determination of the absolute configuration of (−)-abietic acidviaits (4R,5R,9R,10R)-7,13-abietadien-18-ylp-bromobenzoate derivative
The absolute configuration of the title bromo derivative of abietic acid, C27H35BrO2, has been determined. The structural analysis confirms the absolute stereochemistry for (−)-abietic acid proposed by Bose & Struck [(1959). Chem. Ind. (London), pp. 1628–1630] on the basis of optical rotatory dispersion measurements. The molecule exhibits a trans anti 6/6/6 tricyclic hydrocarbon skeleton, with the cyclohexane ring in the expected chair form and the two cyclohexene rings, the double bonds of which are conjugated, in half-chair conformations.