Amino formation

Ethyl. V- 1 2,2-diethoxyethyl )-/V-mcthylcarbamoyl]-2-phcnylcthyl) amino-formate (17) gave ethyl 2-benzyl-4-methyl-3-oxo-1,2,3,4-tetrahydropy-razinecarboxylate (18) [HC1, MeCN, 20°C, 1 h yield unstated ( %)] analogues likewise.248... 

Ethyl chloroformate and methyl anthranilate, heated 15 hr at 100CC, were converted quantitatively to methyl 2-ethoxycarbonyl aminobenzoate (181), which was converted to quinazoline-2,4-dione in excellent yield by heating in ethanolamine for 40 min at 160°C.341 Urethane (ethyl amino-formate) and ethyl JV-phenylanthranilate, when heated at 220°C for 1 hr, gave an excellent yield of l-phenylquinazoline-2,4-dione.342... 

It condenses with resorcinol and amino-phenols to give phthalein and rhodamine dyestuffs respectively. Esters are used in the formation of polyimides. ... 

C. Manufactured from butyrolactone and ammonia. Easily hydrolysed to 4-amino-butanoic acid, its most important use is for the formation of N-vinylpyrrolidone by reaction with elhyne. 

The protein folding problem is the task of understanding and predicting how the information coded in the amino acid sequence of proteins at the time of their formation translates into the 3-dimensional structure of the biologically active protein. A thorough recent survey of the problems involved from a mathematical point of view is given by Neumaier [22]. 

It is important to notice that the united-atom simplification cannot be applied to functional hydrogens which are involved in the formation of a hydrogen hond or a salt bridge. This would destroy interactions important for the structural integrity of the protein. Removing the hydrogen at the u-carbon of the peptide backbone is also dangerous, because it prevents racemization of the amino acid. 

Figure 10.3-40. The rating for the disconnection strategy carbon-heteroatom bonds is illustrated, Please focus on the nitrogen atom of the tertiary amino group. It is surrounded by three strategic bonds with different values. The low value of 9 for one ofthese bonds arises because this bond leads to a chiral center. Since its formation requires a stereospecific reaction the strategic weight of this bond has been devalued. In contrast to that, the value of the bond connecting the exocyclic rest has been increased to 85, which may be compared with its basic value as an amine bond.

The most noteworthy reaction of azo-compounds is their behaviour on reduction. Prolonged reduction first saturates the azo group, giving the hydrazo derivative (C NH-NH C), and then breaks the NH NH linkage, with the formation of two primary amine molecules. If method (1) has been employed to prepare the azo-compound, these two primary amines will therefore be respectively (a) the original amine from which the diazonium salt was prepared, and (6) the amino derivative of the amine or phenol with which the diazonium salt was coupled. For example, amino-azobenzene on complete reduction gives one equivalent of aniline, and one of p-phenylene diamine, NHaCeH NH benzene-azo-2-naphthoI similarly gives one equivalent of aniline and one of... 

Aldehydes and ketones may frequently be identified by their semicarbazones, obtained by direct condensation with semicarbazide (or amino-urea), NH,NHCONH a compound which is a monacidic base and usually available as its monohydrochloride, NHjCONHNH, HCl. Semicarbazones are particularly useful for identification of con jounds (such as acetophenone) of which the oxime is too soluble to be readily isolated and the phenylhydrazone is unstable moreover, the high nitrogen content of semicarbazones enables very small quantities to be accurately analysed and so identified. The general conditions for the formation of semicarbazones are very similar to those for oximes and phenylhydrazones (pp. 93, 229) the free base must of course be liberated from its salts by the addition of sodium acetate. 

When a mixture of aniline, nitrobenzene, glycerol and concentrated sulphuric acid is heated, a vigorous reaction occurs with the formation of quinoline. It is probable that the sulphuric acid first dehydrates the glycerol giving acrolein or acraldehyde (A), which then condenses at its double bond with the amino group of the aniline to give acrolein-aniline (B), The latter in its enol... 

This preparation illustrates the ready formation of the thiazole ring by the condensation of an ot-halogeno-ketone and a thioamide. Thus chloroacetone, which may conveniently be represented in the enol form (I), condenses with thiourea (II) to give 2-amino-4-methylthiazolc (III). 

One starts with individual amino adds or with peptides and tries to achieve the regioselective formation of a new amide bond. In its most general form such syntheses of peptides involve the following stages ... 

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