An asymmetric synthesis of the 3,4-trans-disubstituted piperidine derivative (+)-paroxetine from the chiral non racemic lactam 1 is reported. The p-fluorophenyl substituent is introduced by conjugate addition to the unsaturated lactams 3 whereas the aryloxymethyl substituent at the 3-position is assembled by taking advantage of the activating alkoxycarbonyl group of 3. (C) 1996 Elsevier Science Ltd