Synthesis of 6- and 8-Halogenosubstituted 3-Quinoline-Sulfonic Acid Derivatives[1]
摘要:
Treatment of 3,6‐di‐ and 3,6,8‐trihalogenosubstituted quinolines 1 with sodium alkanethiolates was carried out regioselectively at C3 of the pyridine ring, affording the corresponding halogenosubstituted 3‐methylsulfanylquinolines 2 and 3‐phenylmethylsulfanylquinolines 3. The structures of 2 and 3 were assigned by NMR studies, including 1H‐detected one‐bond (C–H) HSQC and long‐range HMBC, in addition to NOE experiments. Benzyl derivatives 3 were oxidatively chlorinated to obtain the title quinolinesulfonyl chlorides.
Regioselective halogenation of six-membered N-heteroarenes is crucial for precise functional derivatization. We present a meta-selective halogenation method for pyridines, quinolines, and isoquinolines via electrophilic halogen radical addition utilizing an N-benzyl activation strategy. This method achieves C3- and C5-dihalogenation in pyridines, C3- and C6-dihalogenation in quinolines, and C3-monohalogenation