Ionic liquid (tetrachlorocobaltate(II) anion with a dicationic counterion) catalyzed N-Boc protection of amines

Abstract

Ionic liquid (1,1′-hexane-1,6-diylbis(3-methylpyridinium) tetrachlorocobaltate(II) ([C₆(mpy)₂][CoCl₄]²⁻)) catalyzed N-tert-butyloxycarbonylation (N-Boc) of various amines using (Boc)₂O is reported. Halogenated aniline and amino alcohols were converted efficiently to their corresponding N-Boc derivatives without any side products. The reported method is mild, solvent free, uses low amounts of ionic liquid, allows easy product separation and results in high yields of the products. The catalytic efficiency for N-Boc formation in IL is superior to previously reported catalysts.