Strategies for the Design of Organic Aziridination Reagents and Catalysts:  Transition Structures for Alkene Aziridinations by NH Transfer

B3LYP/6-31G* transition structures for aziridination of various alkenes by substituted oxaziridines and diaziridinum salts were located. Oxaziridines substituted with electron-withdrawing groups have activation energies for nitrogen transfer similar to those calculated for epoxidation by various known organic oxidants. These transition states are relatively insensitive to alkene substituents, but highly electron deficient alkenes were calculated to have low activation energies. N-Trimethylsilyl-derived oxaziridines are predicted to be good targets for alkene aziridination reagents. Activation energies calculated for aziridination by diaziridinium salts are generally lower in energy. Aziridinations of electron-rich and highly electron deficient alkenes by diaziridinium salts are predicted to be rapid. N-Methyl, N-trifluoroacetyl, and N-trimethylsilyl derivatives showed reasonable activation energies for nitrogen transfer.