Anilines benzylidene

Benzylidene-aniline. CeH5CH NC6H5.(Semi-microScale.)... 

Mix I ml. of benzaldehyde and i ml. of aniline in a small evaporating-basin, place the latter on a boiling water-bath and stir the mixture gently with a glass rod. Globules of water soon appear on the oily layer. After about 20 minutes place the basin in ice-water, and stir the contents well, whereupon solidification should rapidly occur. (If the material does not solidify, replace the basin on the boiling water-bath for a further 10 minutes.) Break up the solid material in the basin, transfer to a conical flask, and recrystallise from rectified spirit. The benzylidene-aniline is obtained as colourless crystals, m.p, 52° yield, o-8 g. 

Irradiation of 1,2,3-triphenylaziridine (98) in various alcohols has been reported to give benzaldehyde acetals and N-benzylaniline (68T2193). Competitive fragmentation to give N-(benzylidene)aniline and phenylcarbene, which is trapped as the alkyl benzyl ether, also appears to occur. 

Entsprechend wird 4-Hydroxy-N-benzyliden-anilin durch Essigsaure in 4-Hydroxy-N-benzyl-acetanilid (88% d.Th.) iiberfiihrt. 

The group of Bolognese has disclosed a synthesis of thiazolidin-4-ones by condensation of benzylidene-anilines and mercaptoacetic acid (Scheme 6.215 a) [386]. The authors found that microwave heating of an equimolar mixture of the two components in benzene at 30 °C for just 10 min provides excellent yields of the thiazol-idin-4-one heterocycles. Surprisingly, when the same transformation was carried out at reflux temperature (80 °C), much longer reaction times (2 h) were required and the products were obtained in significantly lower yields (25-69%). 

Allyltantalum-mediated allylation of aldimines was reported by Bhuyan et al. in 1993 these workers compared tantalum and bismuth organometallic reagents over a series of transformations. Up to 60% yield was obtained for tantalum-mediated allylation (benzylidene aniline as electrophile). Bismuth reagents offered better yields in the cases compared but, in all cases, a remarkable effect for the addition of Bu NBr was observed.186... 

It is interesting to note that the reaction of N-salicylideneaniline, which possesses a free phenolic hydroxyl group at the ortho position in the benzylidene portion, with the acylzirconocene chloride gives the a-amino ketone in 67 % yield in the absence of any additive (Scheme 5.16) [23]. Similarly, N-(p-hydroxybenzylidene)aniline reacts with the acylzirconocene chloride to give the a-amino ketone in 58 % yield. The reaction of N-(m-hydroxyben-zylidene)aniline, however, gives the a-amino ketone in just 12 % yield. Neither N-(o-MeO-benzylidenejaniline nor N-(p-MeO-benzylidene)aniline gives an appreciable amount of product in the absence of additive. 

A three-component domino reaction of isobutyral-dehyde, N-benzylidene aniline and pyridine-2-thiol as nucleophile gives access to 1,2,3,4-tetrahydroquino-lines as shown by Annunziata et al..161... 

Benzylidene-aniline.—Aniline (1 c.c.) is heated in a test tube on the water bath with an equal quantity of benzaldehyde. The mixture becomes turbid because water separates. On cooling a solid is formed, a so-called SchifE s base (azomethine). Melting point 72°. 

Conversely, activated methylene compounds undergo an addition reaction across the C=N bond of imines. For example, benzylic ketones react with benzylidene anilines to from P-aminoketones [35], whereas the analogous reaction of diphenyl-methylene-protected a-amino esters, and nitriles, produces a disastereomeric mixture of the A-protected a,p-diamino esters, and nitriles [36, 37]. 

Also, the extremely labile trichloride 101 of Viehe salt 100 is reversibly and quantitatively obtained in the solid state [9]. This latter reaction is related to the solid-solid syntheses of the extremely reactive hexachloroantimonates or -phosphates (102) of the Viehe salt by its milling with antimony pentachloride or phosphorus pentachloride [9] (Scheme 11). Furthermore, the labile adduct of chlorine to benzylidene aniline is obtained at -20 °C in a solid-state reaction. 

Solid anilines (236) and solid aromatic aldehydes (77) give the benzylidene anilines 54 upon grinding with 100% yield after drying at 80 °C 20 combinations were performed [101-102] (Scheme 51). A semibatch large-scale experiment of236h with 77b yields quantitatively the hydrated imine 54h that can be dried as well [7]. The reaction of aniline (236s) with benzaldehyde (77k) cannot be run as a solid-state reaction. However, it should be mentioned that the stoichiometric liquid-liquid reaction proceeds with 100% yield because it profits from direct crystallization of the product 54s upon reaction. This technique can... 

For the stoichiometric liquid-liquid large-scale synthesis a flat steel pan (31x44 cm ) was charged with benzaldehyde (77k) (99.5% 848 g, 7.95 mol) and aniline (236s) (99.5% 744 g, 7.95 mol) (Scheme 51). The liquids were mixed at 18 °C. The temperature rose to a maximum of 32 °C and fell back to 24 °C when crystallization started with another increase in temperature to a maximum of 35 °C within 12 min when crystallization was virtually complete and water of reaction separated. Next day, the wet crystal cake was crunched with an ordinary household grain mill and dried in a vacuum at room temperature to give 1.438 kg (100%) of pure benzylidene-aniline (54s). 

Bei der Elektrolyse eines 1 10-Gemisches von N-Benzyliden-anilin und 1,4-Dibrom-butan in Dimethylformamid in Gegenwart von Tetrabutylammonium-jodid an einer Quecksil-ber-Kathode entsteht durch reduktive Cyclokondensation 1,2-Diphenyl-piperidin1 ... 

Auf ahnliche Weise erhalt man z. B. aus 3,4-Dichlor-N-(2,4,6-trimethyl-benzyliden)-anilin durch Deprotonierung mit Butyl-lithium in Tetrahydrofuran und anschlieBende Umset-zungmit 2-Amino-propan, gefolgt von saurer Hydrolyse, 1-Amino-1-( 3,4-dichlor-phenyl)-2-metkyl-propan (90%)2. 

The chlorine group of iV-chloroimines [21] and C-chloro-A-benzylidene-anilines [22] react with Grignard reagents in fair to good yields to give the corresponding imines as described in Eqs. (11) and (12). 

Tertiary alcohols or halides react with hydrazoic acid in sulfuric acid to give imines. Under the same conditions, benzhydrol gives A-benzylidene-aniline in 90 % yield [52]. 

A large number of benzylidene-anilines, substituted in either or both rings, have been tested for phototropic behaviour, Of these, some are phototropic and others not. There is no apparent chemical basis for this distinction and, in fact, the different polymorphic forms of certain compounds have been found to react differently towards light. 

Benzol ani I in. See Benzylidene aniline Benzalazine. Same as Banzaldehyde Azine... 

Keywords chalcone, benzylidene aniline, trimethyloxosulfonium iodide, ylide reaction, cyclopropane, aziridine... 

A mixture of benzaldehyde 1 (0.53 g, 5 mmol), aniline 2 (0.47 g, 5 mmol) and Envirocat EPZGR (100 mg) is placed in a small beaker inside the alumina bath (heat sink) and the contents are irradiated in a MW oven at full power for 1.0 min the reaction is monitored by TLC (hexane-AcOEt, 10 1). The product is extracted into dichloromethane (10 mL) and Envirocat EPZGR is removed by filtration and washed with dichloromethane (3xl0mL). Removal of the solvent on a rotary evaporator affords the benzylidene aniline 3 in 97% yield. 

To an equimolar (1 mmol) mixture of benzaldehyde 2a (106 mg) and aniline la (93 mg) placed in an open glass container, montmorillonite K-10 clay (20 mg) is added and the reaction mixture is irradiated in a microwave oven at full power for 3 min. Upon completion of the reaction, as followed by TLC examination, the product is extracted into dichloromethane (3 x 10 mL). Removal of the solvent under reduced pressure affords the benzylidene aniline 3a in 98% yield. 

The powder THG results are also shown in Table 2. An unesterified azo compound (A-l) shows a small THG at all wavelengths measured in this experiments. On the other hand, ester derivatives such as acetate (A-2), nitrobenzoate (A-3) and acrylate (A-4) show a very large THG. The THG intensity is more than 10 times larger than that of the unesterified compound at 2.05 pm wavelength. The enhancement of THG in powders by esterification is observed not only in azo benzene derivatives but also in stilbene and benzylidene aniline derivative(28k These results have not been expected due to effects on an electronic state because esterification occurs at a hydroxy group... 

Hydroxy-8,9-methylenedioxyphenanthridine, [10]. The method developed by Kessar et al. [11] for phenanthridines and related compounds was applied to the synthesis [10] of 3-hydroxy-8,9-methylenedioxyphenanthridine (22) (Scheme 5). Thus, the benzylidene aniline 23, prepared from 6-chloropiperonal and 3-benzyloxyaniline, was reduced to the secondary amine 24. Treatment of 24 with excess lithium diisopropylamide furnished, on work-up, the benzyl ethers 25 (22%) and 26 (6%) respectively. Catalytic debenzylation of the former generated 22. 

These results indicate that, in acetic acid solution in which indole is unprotonated, the 3-phenyl ring is less reactive than the indole benzo ring, but that in sulfuric acid in which indole is protonated, the 3-phenyl ring is more reactive and the heterocyclic system is para directing. Even in sulfuric acid the 2-phenyl ring is less reactive than the benzene ring of indole (cf. protonated benzylidene aniline, Fig. 2) (66JOC65). 

Benzylidene anilines formed from benzaldehydes and anilines have been found to undergo ortho arylation effectively when a ruthenium catalyst such as [RuC12(/ 6-C6H6)]2 is used in the presence of K2C03 as base (Eqs. 11 and 12) [17]. A polar solvent such as NMP is used. In this reaction the substrates have no acidic hydrogen and thus ortho metalation seems to occur via coordination of the neutral nitrogen to the metal center, as in the reaction of phosphinite (Scheme 3). Similarly, 2-phenylpyridine [18] (Eq. 13) and 2-phenyl-lH-imidazole (Eq. 14) [19] are arylated. 

As stated earlier, disilanes are sometimes reported as byproducts in hydrosilylation reactions. A number of halide complexes of Nb, Ru, Ir, Pd, and Pt were utilized in the reaction of Et3SiH with benzylidene aniline and Et3SiSiH3 was observed as a byproduct in yields up to 38%.139 However, since the aim of these studies is usually hydrosilylation, it is somewhat difficult to identify where disilanes (or other oligomers) are byproducts and the example just mentioned is unlikely to be the only one but could provide clues for complexes for future development. 

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