Synthesis of chiral C-2-symmetric 1,2-diamines by the addition of organolithium reagents to N,N '-bis[(S)-1-phenylethyl]ethanediimine

The additions of alkyl-, phenyl- and vinyllithium reagents to N,N'-bis[(S)- 1-phenylethyl]ethanediimine in THF at -78 degrees C and in DME at -60 degre es C gave high yields of 1,2-diamines with low stereocontrol. Care was take n to quench the reaction mixtures with de-aerated H2O to avoid formation of N-alkylidene-1-phenylethylamines which were formed through homolysis of th e dilithium 1,2-diamides to give alpha-amido radicals which reacted with O- 2/H2O in the quenching step. Pentadienyl-, cinnamyl- and 1-trimethylsilylal lyllithium reagents gave only the linear 1,2-diamines with high yields and moderate to good diastereoselectivities. (C) 2000 Published by Elsevier Sci ence Ltd.