Addition of boranes to N-aryl-salicylaldimines: Intramolecular hydrogenation of imines

Abstract

Addition of boranes to N-aryl-salicylaldimines takes place initially at the reactive phenolic O–H bond to give an activated boron-containing imine and dihydrogen. In some cases a subsequent intramolecular hydrogenation step is observed and the CN imine bond is reduced to the corresponding amine. Reactions with dimesitylborane in THF are unique in that the reduced amine product is the major product observed in solution.