Amino esters, diazotization preparation

Various preparations of antisera to atropine have been reported. A racemic hemisuccinate ester was prepared and conjugated to bovine serum albumin by the carbodiimide technique. Antisera formed to the original immunogen selectively bound the R isomer (34), but a later antiserum prepared by this approach was reported to bind both R and S forms with "equal efficiency" (35). R, S-atropine was treated with diazotized p-amino-benzoic acid, and the resulting compound (which was not further characterized) was used for conjugation to bovine serum albumin by means of a carbodiimide-mediated reaction. Antisera resulting from use of this material were quite selective for the R isomer, with a cross-reaction of only about 2% for the S isomer (36). Virtanen et al. followed this procedure with S-atropine. Their antiserum bound equally to S- and R,S-atropine, as measured by displacement of tritium-labeled R,S-atropine (37). In another study (31), both racemic atropine and the S isomer were coupled to human serum albumin by the technique of Wurtzburger et al. (36), Antisera were obtained that were selective for both the R and S isomers (33). 

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. 

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