Enantioselective synthesis of 3-substituted-4-aryl piperidines useful for the preparation of paroxetine

The asymmetric conjugate addition reaction between 4-fluorophenylmagnesium bromide and various chiral α,β-unsaturated esters and enoylsultam substrates was explored to prepare a key intermediate useful in the preparation of paroxetine. The most selective auxiliary was found to be Oppolzer's (1S)-(−)-camphorsultam. Interestingly, the diastereoselection was opposite to that reported for acyclic enoylsultams.