The highly stereoselective conversion of n,n-dimethylamphetamine into n-methylpseudoephedrine; A mimic of the enzyme mediated stereospecific benzylic h

Treatment of (S)-(η6-N,N-dimethylamphetamine)Cr(CO)3, with n-butyllithium below -40°C gives a stable benzylic carbanion via loss of the pro-R-benzylic proton. Warming of this anion above -40°C gives (η6-E-β-methylstyrene)Cr(CO)3 via an ElcB type elimination whilst trapping with an electrophile below -40°C gives benzylically functionalised amphetamines with overall retention of configuration. The use of oxodiperoxymolybdenum(pyridine)hexamethylphosphoramide as the electrophile gives optically pure (1S,2S)-N-methylpseudoephedrine after decomplexation.