Aliphatic, transamination

A variety of cleavage conditions have been reported for the release of amines from a solid support. Triazene linker 52 prepared from Merrifield resin in three steps was used for the solid-phase synthesis of aliphatic amines (Scheme 22) [61]. The triazenes were stable to basic conditions and the amino products were released in high yields upon treatment with mild acids. Alternatively, base labile linker 53 synthesized from a-bromo-p-toluic acid in two steps was used to anchor amino functions (Scheme 23) [62]. Cleavage was accomplished by oxidation of the thioether to the sulfone with m-chloroperbenzoic acid followed by 13-elimination with a 10% solution of NH4OH in 2,2,2-trifluoroethanol. A linker based on l-(4,4 -dimethyl-2,6-dioxocyclohexylidene)ethyl (Dde) primary amine protecting group was developed for attaching amino functions (Scheme 24) [65]. Linker 54 was stable to both acidic and basic conditions and the final products were cleaved from the resin by treatment with hydrazine or transamination with ra-propylamine. 

The compounds described herein were prepared by three methods. The first route involves deprotonation/substitution at the N-H sites of 1, the second consists of a cleavage reaction of an Si-N derivative of 1 with PhBCI2, and the third route is a transamination reaction between a bis(dimethylamino)boryl derivative of 1 and an aliphatic diamine. In the first approach, compound 1 is deprotonated by treatment with one equivalent of n-BuLi. Quenching of the resulting anion with various electrophiles produces the monosubstituted products 2-4 (eq 3). 

B-Aminoborazines are of particular interest for fundamental studies. In these compounds, boron is bonded to three nitrogen atoms with two different types of environment. B-Aminoborazines are also useful precursors for the synthesis of thermally stable polymers. Quite a few polycondensates of aminoborazines and copolymerisates with organic difunctional molecules have been described 4>. Of major interest are difunctional borazines yielding linear polycondensates. The condensation of l,3,5-tris(2,6-dimethylphenyl)-2,4-dichloroborazine (cf. Section II.2.5) with aliphatic, aromatic, and heterocyclic diamines, as well as the preparation of the same linear polyborazines by transamination of 1,3,5-tris(2,6-dimethylphenyl)2,4-bis(diethyl-amino)borazine with diamines was studied 139). 

A number of studies have shown that natural metabolites can inhibit transamination. With a partially purified mung bean preparation which could use lysine, methionine, or aromatic amino acids as amino donors, it was found that the aliphatic substrates (e.g., lysine and methionine) inhibited the transamination of phenylalanine. The extent of this inhibition was related to their effectiveness as substrates, suggesting that they competed with phenylalanine (Gamborg, 1965). Using the highly purified but multispecific aromatic amino acid (and aspartate) aminotransferase from bush bean. Forest and Wightman (1973) demonstrated that 40 mM aspartate inhibited transamination of L-phenylalanine (40 mM) by 85%. Further experiments showed that elevated concentrations of phenylalanine reduced the inhibition by aspartate double-reciprocal plots indicated competitive inhibition. These... 

This reaction was first reported by Pellizzari in 1894. It is the preparation of 1,2,4-triazole derivatives by baking the mixture of amide and acyl hydrazide. Therefore, it is generally known as the Pellizzari reaction. This reaction is usually carried out at temperatures > 250°C, but very reactive substrates can proceed at relatively lower temperatures, such as the coupling between diphenylformamidine and formhydrazide at 150°C. This reaction is very useful for the preparation of monosubstituted-, disubstituted-, and 1,3,5-trisubstituted-l,2,4-l/f-triazoles. However, at such a high temperature, transamination may occur between amide and acyl hydrazide, especially for the aliphatic acid hydrazides," resulting in a mixture of triazoles and a lower yield of the expected triazole. It has been found that co-heating the mixture of formamide and hydrazine hydrochloride with two equivalents of pulverized KOH can improve the yield of 1,2,4-triazole to almost 17%. ... 

Several simple aliphatic monoamines, formed by decarboxylation of amino acids or by transamination of aldehydes, occur widely in plants (Fig. 28.1) (Geissman and Grout, 1969 Guggisberg and Hesse, 1983 Smith, 1977a,b). Many involve subsequent N-methylation. These compounds are called protoalkaloids in some references (Hegnauer, 1988) more than 1100 compounds of this type are known (Verpoorte et al., 1991). 

Equimolar quantities of -diethylaminopropiophenone hydrochloride and p-chloraniline refluxed a short time in 50%-ethanol y -p-chlorophenylamino-propiophenone. Y 80-90%. F. e. s. J. Gymerman Graig and M. Moyle, Ghem. Ind. 1963, 690 transamination with prim, aliphatic amines and aminocarboxylic acids s. J. Org. Ghem. 28, 2779 (1963). 

Merewialis pereimu.—When aliphatic aldehydes are fed to this plant they are converted into the corresponding primary amines. A transaminase has been isolated which catalyses the transamination between a-amino-acids and aldehydes. L-Alanine was the most efficient amino donor, and all aldehydes in the homologous series from ethanal to undecanal were active amino acceptors. No requirement for pyridoxal phosphate could be demonstrated. In a later publication it was shown that this reaction takes place in many flowering plants. 

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