Amino acids diazotization

Diazotization of a-amino acids in the above solvent at room temperature gives a-fluoro carboxylic acids.If this reaction is run in the presence of excess KCl or KBr, the corresponding a-chloro or a-bromo acid is obtained instead. 

Recently55 a 31P-NMR method for free amino acids was advanced using a reagent derived from (5)-2-butanol and phosphorus trichloride. However, a convenient H-NMR procedure has been described by Kruizinga et al.56 where Schotten - Baumann coupling of a-amino acids with (5)-2-chloropropionyl chloride, available from diazotized (S)-alanine, leads to the diastereo-meric Ar-(5)-2-chloropropionyl derivatives. 

S)-2-Chloroalkanoic acids.1 Diazotization of (S)-2-amino acids (NaN02) in water containing HC1 at 0—>25° results in (S)-2-chloroalkanoic acids in 60-65% yield and with 95-98% ee (equation I). 

Pyrrolidone carboxylyl peptidase activity has been followed using pyrrolidone carboxylyl L-alanine (or other pyrrolidone carboxylyl-amino acids) as substrate by following the amount of amino acid released as determined by the ninhydrin method (137). In another assay procedure the release of -naphthyl amine from L-pyrrolidone carboxylic-/ -naphthylamide (135) is determined by the diazotization procedure of Bratton and Marshall (138) as modified by Goldberg and Rutenberg (139). 

Amino biphenyl, leaflets(from ale), mp 53-55°, bp 302° diff sol in cold w sol in ale, eth, chlf hot w. Was first prepd by Hofmann (Ref 2) from the high boiling residue obtained in the manuf of aniline and named "Xenyla-min . It can also be prepd by the reduction of 4-nitrobiphenyl or by other methods(Ref 1) When a salt of 4-aminobiphenyl, such as the hydrochloride, is treated with NaN02+acid, diazotization takes place. If diazotization of aminobiphenyl is followed by treatment with perchloric acid the resulting compd is an explosive, biphenyldiazonium perchlorate. 

Amino naphtho Is, such as l-amino-2-naphthol and several 1-aminonaphthol-sulfonic acids, such as l-amino-2-naphthol-4-sulfonic acid, are oxidized to the respective quinone by nitrous acid. Diazotization can, however, take place under normal conditions in the presence of catalytic quantities of metal salts, such as copper or zinc salts. 

It is not possible to prepare biaryls containing a free carboxyl group directly by the diazo reaction. No biaryl is formed when (a) diazotized aniline and sodium benzoate, (b) diazotized anthranilic acid and aqueous sodium benzoate, or (c) diazotized anthranilic acid and benzene are used as components in the reaction.13 On the other hand, the reaction proceeds normally if methyl benzoate is used in reaction (a) or when methyl anthranilate replaces the anthranilic acid in (b) and in (c). The success of the diazohydroxide reaction appears to lie in the ability of the non-aqueous liquid to extract the reactive diazo compound from the aqueous layer.4 However, esters and nitriles can be prepared from esters of aromatic amino acids and cyanoanilines and also by coupling with esters of aromatic acids, and from the products the acids can be obtained by hydrolysis. By coupling N-nitrosoacetanilide with ethyl phthalate, ethyl 4-phenylphthalate (VIII) is formed in 37% yield. 

Diazotization of a-amino acids in presence of excess chloride give a-chloro acids1101. 

As the salt solution enters the acid solution, there is a momentary precipitation of the amino acid, which dissolves rapidly as it is diazotized. The checkers found that this addition took about 2 hours. 

The synthesis of [3-lactones has received considerable attention6 since the first representative of this class of heterocycles was prepared in 1883. Classical routes to (3-lactones generally involved the cyclization of (3-halocarboxylate salts6 and the related "deaminative cyclization that occurs upon diazotization of [3-amino acids.9 p-Hydroxy acids undergo a similar cyclization under Mitsunobu conditions,10 and the... 

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