SYNTHESIS OF [C-11](-)-ALPHA,ALPHA-DIDEUTERO-PHENYLEPHRINE FOR IN-VIVO KINETIC ISOTOPE STUDIES

(-)-[C-11]phenylephrine and positron emission tomography could potenti ally be used to assess neuronal monoamine oxidase activity in the hear t. Previous data for (-)-[C-11]phenylephrine indicate that, although i ts retention and neuronal selectivity parallel that of the neuronal ma pping agent (-)-[C-11]hydroxyephedrine, its neuronal storage and clear ance properties are quite different. In order to study the In vivo kin etics of (-)-[C-11]phenylephrine in greater detail, the dideutero anal og [C-11]-(-)-alpha,alpha-dideutero-phenylephrine, 1. was synthesized by [C-11]methylation of the precursor (-)-alpha,alpha-dideutero-m-octo pamine. The key step in the procedure was BD3 reduction of the cyanohy drin derived from 3-hydroxybenzaldehyde. Deuterium incorporation at th e alpha positions of m-octopamine was confirmed by NMR and mass spectr oscopy of the deuterated product and by comparison of spectral data wi th undeuterated m-octopamine. (-)-alpha,alpha-Dideutero-m-octopamine w as methylated with (CF3SO3CH3)-C-11 to give 1 suitable for animal and clinical studies.