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Regioselective C–H Azidation of Anilines and Application to Synthesis of Key Intermediate for Pharmaceutical

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journal contribution
posted on 26.05.2021, 22:31 by Masahiko Seki, Yusuke Takahashi
A catalytic system for regioselective C–H azidation of inactive anilines was developed. In the presence of CuSO4·5H2O, simultaneous addition of NaN3 and Na2S2O8 to aq. CH3CN solution of free anilines under weakly acidic conditions (pH 4.5) smoothly underwent C–H azidation to provide corresponding α-azidated products in high yields. Methyl α-azidoanthranilate obtained by this method was readily transformed via simple reduction followed by cyclization to methyl 2-ethoxybenzimidazol-7-carboxylate, a key intermediate for antihypertensive Candesartan Cilexetil.