toluene-4-sulfonic acid in acetonitrile T=20°C;

zinc(II) chloride 1) 30 min, 2) 3 h; Yield given. Multistep reaction;

1.1: toluene-4-sulfonic acid / N,N-dimethyl-formamide / 20 - 50 °C 2.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 0.5 h / Inert atmosphere 2.2: 20 °C / Inert atmosphere 3.1: hydrogenchloride; sodium cyanoborohydride / tetrahydrofuran; diethyl ether / 5 h / 0 - 20 °C / Molecular sieve 4.1: N-iodo-succinimide; silver trifluoromethanesulfonate / dichloromethane / 0.17 h / 20 °C / Inert atmosphere View Scheme