Stereochemical disposition of the geminal dimethyl groups in the enzymatic cyclization of geranyl diphosphate to (+)-bornyl diphosphate by recombinant (+)-bornyl diphosphate synthase from Salvia officinalis

Regiospecifically deuterated geranyl diphosphate, in concert with NMR spectrometry, was employed to demonstrate that the trans-methyl group (C8) of geranyl diphosphate becomes the C9 carbon of (+)-bornyl diphosphate (geminal methyl syn to the diphosphate moiety) and that the cis-methyl group (C9) becomes the C8 (geminal methyl anti to the diphosphate). The syntheses of the relevant substrates and products, with accompanying spectrometric data are provided.