Sixteen acetylenic amine oxides (5a–p) were prepared by the oxidation of the corresponding tertiary amines (4a–p) with m‐chloroperbenzoic acid. The N‐oxides are thermally unstable and undergo a rearrangement when stirred in an inert solvent yielding O‐allenyl hydroxylamines (6). The rearrangement proceeds by an intramolecular cyclic mechanism.

Carbon‐13 chemical shifts and 2J(POC), 3J(POCC), 2J(PNC) and 3J(PNC) coupling constants of 30 compounds containing the amine moiety, with the general formula Y2PNRR' (Y  C6H5, CH3O, CH3CH2O, CH2O; Y2  1,2‐dioxybenzene) have been determined. J(PNC) values have been used to explain the preferred conformation around the PN bond. A comparison between 2J(PNC) and 2J(PNH) was accomplished.

In the present work, some new 1,3,4-Oxadiazole derivatives have been synthesized from Ethyl-2-Piperidone-3-Carboxylate. The reaction of the ethyl ester with hydrazine hydrate afforded the corresponding hydrazide (I). Treatment of the latter compound with different aromatic aldehydes yielded a new hydrazones (II). Preparation of 1,3,4-Oxadiazoles (III) have been achieved by oxidative cyclization of hydrazones (II) by the use of lead dioxide in glacial acetic acid. The structural formula of the synthesized compounds were established by physical and spectral methods.

Three new series of 4-aminohippuric acid ester derivatives have been prepared. The azo (4a-f) and azoamino (5a-e) compounds were prepared from electrophilic addition reaction of 4-diazonium chloride hippuric acid ester with phenols, aniline and secondary aliphatic amines, while Schiff bases(6a-g) were prepared from the condensation of 4aminohippuric acid ester with aldehydes. The structural formula of the prepared compounds were confirmed by physical and spectral methods.

N‐Oxides such as (V), obtained from readily available corresponding amines such as (IV), are very unstable undergoing facile rearrangement to O‐dienyl‐substituted N‐hydroxyamines such as (VI).