Effective tuning of the arene and alkanesulfinamides for highly enantioselective synthesis of (S)-4-chlorophenylphenylmethylamine, a key intermediate for antihistamic (S)-cetirizine

High diastereoselectivity (>94%) has been achieved in the phenylMgBr addition process to chlorophenyl aldimine derived from the new and sterically hindered triisopropylbenzene sulfinamide (TIPBSA) in the synthesis of a key intermediate of (S)-Cetirizine. Surprisingly, under the same reaction conditions, toluenesulfinamide derived chlorophenyl aldimine provided only 10% ee.