Other Alkylations and Allylations of Imines

Primary alkyl radicals have been generated from alkyl iodides (RCH2I) using dimethyl-zinc and air as initiator the radicals can then be used to alkylate iV-tosylimines, ArCH=NTs, to give the corresponding amines, ArCH(CH2R)NHTs42 The latter process is promoted by BF3 etherate and catalysed by copper(II). 

Di(f-butyl) tartrate has been used as an auxiliary to give asymmetric addition of alkynylzincs to nitrones, yielding optically active a-substituted propargylic N-hydroxylamines.43 Addition of product-like iV-hydroxylamine boosted ees up to 95%. 

A C2-chiral bisformamide (18) derived from diaminocyclohexane catalyses the enantioselective allylation of simple aldimines, using allyltrichlorosilane in the presence of L-proline.44 The more immediate allylating agent is, in fact, L-proline derivative (19), formed in situ, and observed by NMR and MS. 

Phenols have been employed as directing groups in the enantioselective allylation of aldimines and ketimines using allylchlorosilane reagents.45 

Regio- and stereo-selective allylation of sulfonylimines has been carried out with trifluoro(allyl)borates and allylstannanes, using palladium-pincer complexes as catalysts.47 Syn products predominate, in contrast to the corresponding reaction of aldehyde electrophiles DFT calculations have been employed to probe the mechanistic differences. 

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