Aminomethylating reagents imines

High enantioselectivity has been achieved on addition of diethylzinc to benzaldehyde catalysed by a chiral diamine, (,S )-2-(A,A -disubstitutcd aminomethyl)pyrrolidine,116 and by chiral helical titanate complexes of tetradentate ligands.117 Enantioselective additions of dialkylzinc reagents to A,-(diphcnylphosphiiioyl)imines, promoted by aziridino alcohols,118 and to the carbon-nitrogen double bond of the nitrone 3,4-dihydroisoquinoline A-oxide, promoted by dicyclopentyl(R,R)-tartrate,119 have also been reported. 

Apart from rare exceptions, preformed reagents (Fig. 19) are intermediate derivatives having the structure of methyleneimmonium salts (31), X-aminomethyl compounds (32, X = heteroatom see Table 5, below) and imines (33), produced by different routes and capable of readily giving Mannich reactions with the appropriate substrate. 

Aminomethylation. The reagent is deprotonated by LDA in THE at -60° to give 2, which reacts with aikyi bromides (also allyl bromides) to form imines... 

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