Benzylamines, metalation

Activation of benzylamines. Metallation at the benzylic position of benzylatyines is facilitated after forming the borane complexes. 

In general the method is more satisfactory with esters of aromatic acids than with esters of aliphatic acids. Esters of alcohols other than methyl and ethyl are best treated by first converting them into methyl esters thus Heat together under reflux i ml. of the higher ester, 5 ml. of methanol and 0-2 g. of sodium methoxide. [In place of the sodium methoxide, it suffices to add o i g. of metallic sodium to the methanol.] After refluxing, distil off the excess of methanol (b.p, 65 ). The residue is then heated under reflux with benzylamine as described above. 

The unusual reactivity pattern of benzylamine and carbon tetrachloride under the influence of metal carbonyl catalysts is paralleled by the behavior... 

The separately treated METAL ALKOXIDES may perhaps be regarded as organic bases, as well as the more conventional nitrogenous bases below Aminoguanidine, 0507 1-Amino-2-propanol, 1311 Benzylamine, 2812 Benzyldimethylamine, 3168 Bis(2-aminoethyl)amine, 1777... 

Heteroalkenes, with iron, 6, 132 Heteroannulation, allylic benzylamines, 10, 156 Heteroarene chromium carbonyls, preparation and characteristics, 5, 260 Heteroarenes borylation, 10, 242 C—H functionalizations, 10, 127 as metal vapor synthesis milestone, 1, 237 with titanium, 4, 246 vanadium complexes, 5, 48 7]6-Heteroarenes, with platinum, 8, 664 Heteroaromatic compounds... 

So far in this section the examples discussed have comprised of hetero aromatic antenna receptors, which mainly function as pH sensors. The detection of metal cations in biological, medical and ecological applications is of major interest. However, this requires more elaborate receptors that can selectively bind a specific metal cation. Naturally, the more elaborate the receptor required, the more challenging its synthesis becomes. The synthesis of lanthanide-based sensors of 53 and 54 has been reported with each ligand incorporating an antenna/receptor selective for zinc(ll) [158,159]. In both cases the receptors are structurally similar, with 53 synthesised from benzylamine and 54 from aniline. 

The metalation of benzylamines is similarly interesting, because slight variations of the reaction conditions can significantly alter the regioselectivity of proton removal. Treatment of N,N-dimethylbenzylamine with organolithium compounds leads to dean ortho-metalation of the phenyl group [418, 431], If, however, phenyl-sodium [432] or mixtures of organolithium compounds and KOfBu [193, 209, 433]... 

Chiral addition of allyl metals to imines is one of the useful approaches toward the synthesis of homoallylic amines. These amines can be readily converted to a variety of biologically important molecules such as a-, / -, and y-amino acids. Itsuno and co-workers utilized the allylborane 174 derived from diisopropyl tartrate and cr-pinene for the enantioselective allylboration of imines. The corresponding iV-aluminoimines 173 are readily available from the nitriles via partial reduction using diisobutylaluminium hydride (DIBAL-H) <1999JOM103>. Recently, iV-benzyl-imines 176 have also been utilized for the asymmetric allylboration with allylpinacol boronate 177 in the presence of chiral phosphines as the chiral auxiliaries to obtain homoallylic A -benzylamines 178 in high yield and selectivity (Scheme 29) <2006JA7687>. 

Mixtures of metallic detergents, such as phenates, sulfonates, phosphonates, and salicylates with ashless dispersants such as succinimides and benzylamine, together with zinc dialkyldithiophosphate (ZDDP), can lead to new effects. The possible interactions between these main additives used in lubricating formulations when dissolved/dispersed in hydrocarbon media are shown in Fig. 2.8 together with an indication of the intensity of those respective interactions. 

The typical detergent-dispersant additives used in modem lubricating oils are metallic detergents/sulfonates, phenolates, phosphonates, salicylates, ashless dispersants/succinimides and benzylamines. Water is solubilized by strong ion-dipole interactions. The solubilization of water (Watanabe, 1970) by hydrogen bond formation with succinimides and the amount solubilized is smaller than that solubilized by sulfonates. 

A purpose designed CEC stationary phase that gives excellent EOF character yet allows rapid simultaneous acidic, basic and neutral separations under isocratic conditions without tailing is yet to be discovered. Nevertheless, the Hypersil BDS unbonded silica used in this work was taken forward to explore such complex mixture separations as it combines features of both pure and traditional media. As a phase, it possesses a reasonable EOF (as it is based on traditional silica) with a lower number of activated silanol groups on the silica surface (due to the pre-treatment procedure used to remove surface metal contamination). Figure 3.3 shows the separation of benzylamine, caffeine and p-hydroxybenzoic acid in a single chromatographic analysis. 

For 2-benzylaminopyridine the methods of significance in the literature are condensation of 2-pyridinesulfonic acid and benzylamine,4 condensation of the alkali metal salts of 2-amino-pyridine with benzyl chloride,6 reductive alkylation of 2-amino-pyridine in the presence of benzaldehyde and formic acid,2 oxidation of N-benzyl-N-pyridylaminoacetonitrile or N-benzyl-N-pyridylaminoacetaldoxine,6 and the method described here modified by use of an inert solvent.7... 

Benzyl groups are the second fiddles of the amine protection repertoire, and they are especially useful when a substrate is to be subjected to powerful orga-no metal lie reagents or metal hydrides which might attack a carbamate. Benzyl-amines are not generally cleaved by Lewis acids under preparatively useful conditions. The following discussion embraces benzylamines, diphenylmethylamines and their methoxy-substituted derivatives. 

Three milhgrams apiece of the Step 1 and Step 2 products were dissolved in 10 ml of water and 1 ml of methanol by heating the solution to 70°C. This mixture was then treated with tetraethoxysUane (20 mg) followed by benzylamine (6 mg). A gel that formed during gradual cooling of the mixture stood uninterrupted at ambient temperature for seven days. The sample was then sintered in a nitrogen gas atmosphere first for two hours at 200°C and then for four hours at 500°C, and metal oxide nanotubes were isolated. 

Amines containing a Chiral carbon center in the aliphatic residue attached to the nitrogen atom, for example, o -methyl benzylamine (24), (25), are of considerable interest to the coordination chemist as, when coordinated, these ligands induce chirality in the metal-ligand chromophore. Methods for the resolution of more than 1000 racemic nitrogen containing organic compounds have been described. ... 

In the presence of a catalytic amount of a metal carbonyl, benzylamine reacts with carbon tetrachloride to form a mixture of 2,4,5-triphenylimidazole and 2,4,5-triphenyl-2-imidazo-line. The reaction is probably of the free radical type involving, ultimately, cyclization of a species such as (57). When hydrobenzamide (58) is treated with an acid chloride in the presence of triethylamine the product is an iV-acyl-3-imidazoline (59). When, however, (58) is heated and subsequently reacts with an acid chloride in the presence of triethylamine, the isomeric 2-imidazoline is formed (Scheme 31) (72JOC2158). 

CE has been widely used for the analysis of metal ions generally with indirect UV detection. A recent volume of J. Chromatography (201 has covered developments and applications. Typically a small amine such as imidazole or benzylamine is added to the buffer to provide the background UV absorbance signal. Low-pH buffers are normally employed to suppress EOF flow and enhance resolution. Selectivity of metal ion separations can be modified (21 ( by the addition of small oiganic acids such as lactic or formic acid. 

TriarylimidazoIes have been isolated from reactions of alkenes, carbon monoxide and ammonia in the presence of a rhodium catalyst, while benzylamines react with catalytic quantities of metal carbonyls to form the same compounds [69, 70]. 4-Aminoimidazolium salts have been made by assembling iminochloro sulfides, benzaldimines and isocyanides in a process believed to involve a transient 7V-imidobenzylideniminium halide intermediate. Yields of 25-76% are reported [71]. 

Metal oxide catalyzed reactions of anilines and benzylamines have been utilized to synthesize azobenzenes and A-benzylidenebenzyl amines in good yields (Scheme 32) [67, 241, 242],... 

There have been reports of a novel synthesis of 2,4,5-trialkyl-imidazoles by the rhodium-catalyzed reactions of alkenes with carbon monoxide and ammonia. Yields are 50-60%. Benzylamine and derivatives react with carbon tetrachloride in the presence of a catalytic amount of metal carbonyls to yield 2,4,5-triarylimidazoles and -imidazolines. The suggested reaction mechanism implicates an initially formed radical species which coordinates with the metal carbonyl. 

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