Synthesis of (2S,3S)-β-(trifluoromethyl)-α,β-diamino acid by Mannich addition of glycine Schiff base Ni(II) complexes to N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimine

• A chiral CF3-bearing sulfinimine is a suitable Mannich acceptor upon reaction with Ni(II) complexes of glycine Schiff bases.
• The Mannich reaction proceeds with very high diastereoselectivity starting from an achiral Ni(II) complex.
• The optically pure free diamino acid is released from the Ni(II) complex with recovery of the chiral ligand.

A convenient access to (2S,3S)-β-(trifluoromethyl)-α,β-diamino acid is reported by using highly diastereoselective Mannich addition reactions of either chiral or achiral Ni(II) complexes derived from glycine Schiff bases to a chiral sulfinimine, N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimine. Disassembly of the resultant Ni(II) complexes affords the target amino acid which was, for the first time, isolated in enantiomerically pure form and fully characterized.

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