Sulfur Ylide-based Aziridination of Imines

The required chiral sulfur ylide of type 59 is formed in a reaction with a diazo compound in the presence of an achiral metal catalyst. Subsequently, asymmetric reaction of the chiral ylide 59 with the C=N double bond of the imine proceeds diastereoselectively and enantioselectively, giving the optically active aziridine 57. The chiral sulfide catalyst released is then used for the next catalytic cycle. The cat-alytically active species in the asymmetric process is the sulfide, so this concept can also be regarded as an organocatalytic reaction. 

The use of stoichiometric amounts of sulfur ylides in the diastereoselective addition to imines has been recognized for a long time as a means of efficient synthesis 

Screening of several sulfide catalysts revealed that sulfide 64 is the most efficient, although other sulfide catalysts also gave high enantioselectivity [81]. To improve the diastereoselectivity further, the effect of an electron-withdrawing N-substituent 

The range of diazo compounds as substrates was also studied. It was found that 

Study of the scope and limitations of the reaction revealed that a broad variety of aldimine is tolerated [83]. These reactions were conducted with a loading of orga- 

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