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Trifluoromethyl aldimines derived from α-amino esters have proven to be very good starting materials to obtain the title compounds. A Ag 2 O-catalyzed Mannich-type/cyclization cascade reaction starting from suitable α-isocyano acetates leads to enantiopure valuable trans -carboxylic trifluoromethyl substituted 2-imidazolines by a highly stereoselective addition without the need to add organocatalysts. [ABSTRACT FROM AUTHOR]

Abstract: Chiral racemic α-diimines, tested in aziridination reactions with NsONHCO2Et, for the first time led to the synthesis of (±)-bidiaziridines, stereoselectively derived from the corresponding meso (E-s-trans-E)-α-diimines. Moreover, a minor bidiaziridine isomer, probably a meso form that was lost under classical work-up conditions, can be obtained by adding water to the crude mixtures at the end of amination reactions. The results definitively prove that the imine aziridination by carbamates is a two-step domino process. The structures of the compounds were determined using 2D NMR on purified bidiaziridines. [Copyright &y& Elsevier]