Aminierende, reduktive Kupplung aromatischer Aldehyde mit Tris(dialkylamino)methylvanadium(IV) zu N,N,N',N'-Tetraalkyl-1,2-diarylaethylendiaminen

Article abstract of DOI:10.1002/hlca.19840670612

In a novel type of reaction, certain aromatic aldehydes (benzaldehyde, p-methoxy-benzaldehyde, 1-naphthaldehyde, furan-2-carbaldehyde) and secondary amines are coupled to give N,N,N',N'-tetraalkyl-1,2-diarylethylenediamines 1-6.The reagents are tris(dialkylamino)methylvanadium(IV) compounds (cf.Eqn.2).These are generated in situ either from isolable chlorotris(dialkylamino)vanadium(IV) (Eqn. 3), or preferably, from an Et2O/pentane solution of VCl4 which is treated sequentially with 3 equiv. of lithium dialkylamide, 1 equiv. of MeLi, and equiv. of aromatic aldehyde, to give the products 1-6 in a one-pot preparation (Schem 2).The yields range from 14 to 54percent.The diastereomeric mixtures (meso- and (+/-)forms) obtained are separated by chromatography (Al2O3, petroleum ether/Et2O/Et3N), and the pure stereoisomers fully characterized.A mechanism of the reductive coupling induced by CH3V(NR2)3 is proposed (Scheme 1).