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When n-valeric acid was treated with allyl diethyl phosphite and diethyl azodicarboxylate, allyl valeriate and diethyl N-(diethyl)phosphoryl hydrazodicarboxylate were obtained in good yields. Similarly ethyl benzoate was obtained in a nearly quantitative yield by the reaction of benzoic acid with triethyl phosphite and diethyl azodicarboxylate. The reaction of carboxylic acid with triphenyl phosphine and diethyl azodicarboxylate in the presence of an alcohol resulted in the formation of the corresponding esters of the carboxylic acid, triphenyl phosphine oxide, and diethyl hydrazodicarboxylate.The mechanisms of these reactions are also discussed. diethyl allyl phosphite (1 mol) with diethyl azodicarboxylate (1 mol) was first studied, on the assumption that acyl phosphate, allyl valeriate, and diethyl hydrazodicarboxylate would be formed. However, instead of the expected products, allyl valeriate and diethyl N-(diethyl)phosphoryl hydrazodicarboxylate (I) were obtained in 71% and 77% yields respectively, while about 1 mol of the valeric acid was recovered unchanged (54%).Similarly, the reaction of benzoic acid 4.2) and triethyl phosphite with diethyl azodicarboxylate at room temperature resulted in the formation of ethyl benzoate and diethyl N-(diethyl)-phosphoryl hydrazodicarboxylate in 95% and 95% yields respectively. The results are summarized in Table 1.(1)The reaction can be explained in the following manner. An imidoyl phosphonium salt (II) initially formed is protonated, giving an phosphonium carboxylate (III). This phosphonium carboxylate (III) is then, in turn, decomposed into an ester of carboxylic acid and diethyl N-(diethyl)phosphoryl hydrazodicarboxylate by the migration of the alkyl group to the carboxylate anion (Eq. (2));

Trivalent phosphorus compounds, phosphine or trialkylphosphites, have been oxidized by means of diethyl azodicarboxylate and either benzyl or allyl alcohol to give the corresponding phosphine oxide or trialkyl phosphates. The reaction was then extended to the phosphorylation of alcohols. When allyl diethyl phosphite was treated with diethyl azodicarboxylate in the presence of an alcohol at room temperature, a corresponding alkyl diethyl phosphate and diethyl N-allyl hydrazodicarboxylate were obtained in good yields. On the other hand, when phenol was treated with allyl diethyl phosphite and diethyl azodicarboxylate, diethyl phenyl phosphate, allyl phenyl ether and diethyl hydrazodicarboxylate were obtained. The mechanism of their formation will also be discussed.

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