Addition of Me₃SiCN to trifluoromethyl derivates of N‐(pyridylmethylidene) anilines catalyzed by Lewis acids

Abstract

A series of novel Shiff bases (1a-h) was synthesized by condensation of pyridinecarboxaldehydes (1-4) with 3-and 4-trifluoromethylanilines (5, 6) in the presence of molecular sieves (4 Å ). It was found that AlCl 3 and AlBr 3 catalyzed the addition of Me 3 SiCN to the C=N bond of the imines obtained, whereas the other Lewis acids studied (YCl 3 , LaCl 3 , ZnI 2 ) were not active. The reactivity of the imines in the title reaction, on the whole, correlated with their basicity. Besides the addition giving the expected a-amino nitriles (2a,b,d-f,h), an unusual reaction leading to unsaturated nitriles (3a-h) was observed. The structures of saturated and unsaturated products 2d and 3c were determined by X-ray diffraction.

Synthesis, structure and quantum chemical calculations on p-trifluoromethylphenyl thioacid amide

“…C-N bond distances are also good agreement with those C-N single bond distances [14]. The bond lengths of C-F are from 1.222 to 1.348 Å , which are consistent with those found in the derivates of trifluoromethylphenyl, such as N-(4-pyridyl(cyano)methylidene)-3-trifluoromethylaniline [1.205(3), 1.223(5), 1.237(5) Å ] [15], N-(6-methyl-2-pyridyl(cyano)methyl)-3-trifluoromethylaniline [1.278(2), 1.270(4), 1.298(5) Å ] [15] and 5-(3-trifluoromethylbenzylidene)-thiazolidine-2,4-dione [1.332(4), 1.326(4), 1.332(5) Å ] [16]. From the view of Fig.…”

Diastereoselective addition of trimethylsilyl cyanide to chiral O‐, S‐ and N‐heterocyclic aldimines

“…This fact suggests that the pyridine N-atom plays some role in the formation of products 3 (yields in our conditions were up to 33% Ð run 10, Table 5). Comparable results were obtained in previous investigations 25,26 of Me 3 SiCN addition to imines (produced from reactions of furan, thiophene and pyridine aldehydes with unchiral amines), and were also accompanied by the formation of the corresponding unsaturated compounds from pyridine imines only. Apparently, the pathway to unsaturated nitriles is achieved via formation of the intermediate s-complex of AlX 3 with imine (through the N-atom of the pyridine ring) leading to an increase in the hydrogen atom mobility in the CH=N group.…”

New iron-based bis(imino)pyridine and acetyliminopyridine complexes as single-site catalysts for the oligomerization of ethylene

“…2,6-Bis [1-(3-methoxyphenylimino)ethyl]pyridine (1a) [19]: 2,6-diacetylpyridine (0.74 g, 4.5 mmol) was stirred with m-anisidine (1.83 g, 15 mmol, 3.3 eq) in 20 ml of dry benzene at ambient temperature in the presence of 8.5 g of molecular sieves. The reaction was performed under argon in a closed flask for approximately 50 days.…”

“…Yield: 1.1 g (3.0 mmol, 66%). 1 [19]: 2,6-diacetylpyridine (0.82 g, 5.0 mmol) was stirred with 3-trifluoromethylaniline (1.62 g, 10 mmol, 2 eq) in 25 ml of dry benzene at ambient temperature in the presence of 2.8 g of molecular sieves. The reaction was performed under argon in a closed flask for 48 h. The molecular sieves were removed by filtration, the reaction mixture was concentrated and a few ml of dichloromethane were added.…”