Simple and highly diastereoselective synthesis of trifluoromethyl-containing myosmines via reaction between 2-(aminomethyl)pyridine and 1,1,1,5,5,5-hexafluoro-2,4-pentanedione

The reaction between 1,1,1,5,5,5-hexafluoro-2,4-pentanedione and 2-(aminomethyl)pyridine, or its salts with carboxylic acids, was found to produce a mixture of diastereomeric 2-(2′-pyridyl)-3-hydroxy-3,5-bis-trifluoromethyl-1-pyrrolines with high (up to 85% de) of kinetic (3R*,5S*)-diastereoselectivity. The thermodynamic (3R*,5R*) diastereomer was prepared as a major product (90% de) by epimerization of the kinetic (3R*,5S*) diastereomer with triethylamine.