Determination of the absolute stereochemistry of the epoxide group in alpinia epoxide by NMR.

The absolute stereochemistry of the epoxide group in alpinia epoxide [14,15-epoxylabda-8(17),12-dien-16-al (E)] has been determined by simultaneous reduction of the aldehyde and epoxide functional groups in this molecule to primary and secondary alcohols, followed by selective protection of the primary alcohol and derivitization of the secondary alcohol with S(+) and R(-) MTPCl as Mosher esters. Changes in (1)HNMR chemical shifts for all positions in these two esters were determined by 2D-NMR and used to infer the absolute stereochemistry of the epoxide group in the natural product alpinia epoxide.