Grignard reagents, alkyl reaction with cyclohexanone

When cyclohexanone oxime 6e was used as amination reagent, primary amines were obtained from phenylmagnesium bromide. Reaction of 6e with alkyl Grignard reagents gave aziridines, whereas reaction with phenyllithium gave aziridine and the addition product of phenyllithium to the imine (Scheme 57) 24. 

MAD and MAT have played a crucial role in the stereoselective synthesis of hitherto inaccessible equatorial carbinols from cyclohexanones and primary allyl Grignard reagents or methyllithium [44). In the reaction of cyclohexanone derivatives with tert-butylmagnesium chloride, reduction takes precedence over alkylation in the presence of MAD (Scheme 6.37) [45). 

Chiral sulfinimines 236 are very useful intermediates for the preparation of enantiomer-ically pure primary amines 237 (equation 158) . This reaction has been applied to the synthesis of a-amino acids . For sulfinimines obtained from simple ketones, lithium reagents are preferable for the addition , while for cyclic ketones organomagnesium compounds gave the best results. Addition of alkyl and aryl Grignard compounds to sulfinimines, derived from 3- and 4-substituted cyclohexanones, proceeds with excellent diastereoselectivity, depending on the stereochemistry of the ring substituents rather than the sulfinyl group . 

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