Aminierende reduktive Kupplung aromatischer Aldehyde mit niervalenten Titan‐Reagenzien zu 1,2‐Diarylethylendiaminen

Preparation of 1,2‐Diarylethylenediamines by Aminative Reductive Coupling of Aromatic Aldehydes with Low‐Valent Titanium Reagents In a novel McMurry‐ Type one‐pot reaction, aromatic aldehydes and secondary amines are poupled of give the N, N, N′, N′‐tetraalkyl‐1,2‐diarylethylendiamines 1–22 (Table 3). To this end, a lithium dialkylamide is added to an aromatic aldehyde to give the adduct B which is then treated with 1 equiv. of TiC14 to yield a coloured suspension of a reagent synthetically equivalent to a iminium salt (C/D in Scheme 4). After treatment with a low‐valent Ti reagent which is prepared by reduction of TiC14 with either K or, preferably, Mg, the coupling products are isolated in 23 to 81% yield as a 1:1 mixture of the diastereoisomers (meso‐ and rac‐form). These are separated either by chromatography or by crystallization and characterized.