Synthesis of (R)-[2-H-2]isopentenyl diphosphate and determination of its enantiopurity by H-2 NMR spectroscopy in a lyotropic medium

[GRAPHICS] The synthesis of (R)-[2-H-2]isopentenyl diphosphate from D-mannitol 1,2:5,6 -bis acetonide in 10 steps is reported. Stereospecific incorporation of the label is achieved by a BF3-catalyzed NaCNBD3 reduction of the enantiomeric ally pure (S)-isopropylidene oxirane intermediate. The enantiomeric excess of the penultimate precursor [2-H-2]isopentenyl tosylate (>95% ee) was dete rmined by H-2 NMR spectroscopy in a poly-gamma-benzyl-L-glutamate/CH2Cl2 li quid crystal at -50 degrees C.