Aminomethyl Transfer (Mannich) Reactions Between an O‐Triethylsilylated Hemiaminal and Anilines, R_nC₆H_5−nNH₂ Leading to New Diamines, Triamines, Imines, or 1,3,5‐Triazines Dependent upon Substituent R

Abstract

The reactions of the Mannich reagent Et 3 SiOCH 2 NMe 2 (1)w ith av ariety of anilines (mono-substituted RC 6 H 4 NH 2 ,R = H, 4-CN, 4-NO 2 ,4 -Ph, 4-Me, 4-MeO, 4-Me 2 N; di-substituted R 2 C 6 H 3 NH 2 ,R 2 = 3,5-(CH 3 ) 2 ,3 ,5-(CF 3 ) 2 ;t risubstituted R 3 C 6 H 2 NH 2 ,R 3 = 3,5-Me 2 -4-Bra nd a" superb ulky" aniline (Ar*NH 2 )[ Ar* = 2,6-bis(diphenylmethyl)-4-tert-butylphenyl]) led to the formation of ar ange of products dependent upon the substituent. With electron-withdrawing substituents, previously unknown diamines, RC 6 H 4 NH(CH 2 NMe 2 ) [R = CN (2a), NO 2 (2b)] and R 2 C 6 H 3 NH(CH 2 NMe 2 )[ R 2 = 3,5-(CF 3 ) 2 (2c)]w ere formed. Further reaction of 2a, b, c with 1 yielded the corresponding triamines RC 6 H 4 N(CH 2 NMe 2 ) 2 (R = CN (3a), NO 2 (3b)a nd R 2 C 6 H 3 N(CH 2 NMe 2 ) 2 ,R 2 = 3,5-(CF 3 ) 2 (3c). The new polyamines were characterized by NMR spectroscopy,a nd for 2a, 2c , and 3c,b ys ingle crystal XRD. In the case of electron-donating groups, R = 4-OMe, 4-NMe 2 ,4 -Me, 3,5-Me 2 ,3 ,5-Me 2 -4-Br, and for R = 4-Ph, the reactions with 1 immediately led to the formation of the related 1,3,5triazines, R = 4-MeO (5a), 4-Me 2 N( 5b), 4-Me (5c), 3,5-Me 2 (5d), 3,5-Me 2 -4-Br (5e), 4-Ph (5f), 4-Cl (5g). The "super bulky" aniline rapidlyp roduced as ingle product, namely the corresponding imine Ar*N=CH 2 (4)w hich was also characterized by single crystal XRD. Imine 4 is both thermally and oxidatively stable. All reactions are very fast, thus based upon the presence of Si we are tempted to denote the reactions of 1 as examples of "Silick" chemistry.Scheme1.Suggestedmechanism for 1,3,5-triazine formation.