Chiral nitrido complexes

The nitrido complex was applied to the direct asymmetric animation with a silyl enol ether as a substrate. Although several examples for achiral aminations of silyl enol ethers have been reported [32], an asymmetric version of reagent-controlled reaction has not appeared except for the one recent example [33] and the diastereoselective reactions with silyl enol ethers having a chiral auxiliary [34], The amination, which is presumed to take place via an aziridine intermediate [5g, lid,32], proceeded smoothly to give the A-tosylated a-aminoketone in 76% yield with 48% ee. When the same silyl enol ether was treated with complex 15 under Carreira s condition, the TV-trifluoroacetylated a-aminoketone was obtained in 58 % yield with 79 % ee (Scheme 24). 

Very recently, Jprgensen s group reported the preparation of some chiral nitrido-manganese complexes, which closely resemble those synthesized by the authors group, and the application to asymmetric amination of silyl enol ethers with the chiral complexes using Carreira s method [35], These results were very similar to those of the authors [22]. 

Chiral analogs of the Carreira systems were studied by Komatsu, who reported that good levels of enantioselection could be obtained in the aziridination of certain trans-olefins with a 1,2-diaminocyclohexane-derived (salen)Mn-nitrido complex (Scheme 3) [9]. 

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