Cobalt(II)/TPPMS-Catalyzed Dehydrative Nucleophilic Substitution of Alcohols in Water

A green and sustainable direct dehydrative amination of alcohols, catalyzed by cobalt(II)/TPPMS (sodium diphen-ylphosphinobenzene-3-sulfonate) in water, is described. Earth-abundant cobalt is used in form of Co(hfac) 2 center dot xH(2)O (hfac: hexa-fluoroacetylacetone), which acts as a highly efficient Lewis acidic catalyst. This simple atom-economical protocol features mild conditions without the need for a base or other additives and affords the corresponding benzylic and allylic anilines along with water as the only coproduct. Mechanistic studies suggest that this system is driven by direct nucleophilic substitution of alcohols.