Synthesis of (1S)-1-amino-2,2-dimethylcyclopropane-1-carboxylic acid via PLE mediated hydrolysis of bis(2,2,2-trifluoroethyl) 2,2-dimethylcyclopropane-1,1-dicarboxylate

Hydrolysis of bis(2,2,2-trifluoroethyl) 2,2-dimethylcyclopropane-1,1-dicarboxylate with pig liver esterase afforded (1R)-2,2-dimethyl-1-(2,2,2-trifluoroethoxycarbonyl)-cyclopropane-1-carboxylic acid in high enantiomeric excess. This compound was rearranged to (1S)-2,2,2-trifluoroethyl-2,2-dimethyl-1-[(N-ethoxycarbonyl)amino]-cyclopropane-1-carboxylate via a Curtius type reaction with DPPA. Final alkaline hydrolysis gave (1S)-1-amino-2,2-dimethylcyclopropane-1-carboxylic acid.