Addition of borane-protected secondary phosphines to imines. A route to protected mono-N-substituted-alpha-aminophosphines

Addition of a secondary phosphine-borane adduct to imines was examined in o rder to improve the synthesis of mono-N-substituted-alpha-aminophosphines. The reaction demonstrates, for the first time, successful addition of a pho sphine-borane to a multiple carbon-nitrogen bond. The process tolerates a r ange of substituents on the imine and results in an efficient formation of a borane-protected alpha-aminophosphine, Borane protects the aminophosphine and improves the reliability of the Mannich-like phosphine addition to imi nes. (C) 2000 Elsevier Science Ltd. All rights reserved.