Oximes, reaction with hydrazoic acid

The same products were also obtained by treatment of quinuclidin-3-one (2) with hydrazoic acid under Schmidt reaction conditions175 here the process gives mainly the monocyclic amide (147). Reaction of quinuclidin-3-one oxime (103) with arylsulfonyl chlorides in alkali leads to fragmentation and formation of iV-substituted 3-cyano-piperidines.179,177... 

Tetrazoles.—a-Azido-oximes, R C(N3)=NOH, cyclize to l-(acyloxy)tetrazoles (661) when treated with acid chlorides RCOCl. The action of hydrazoic acid on unsymmetrical carbodi-imides PhN=C=NR (R = alkyl) leads to l-phenyl-5-(alkylamino)tetrazoles (662) at 200 °C, these undergo a Dimroth rearrangement to yield the l-alkyl-5-anilino-isomers (663)/ ° (Diphenylmethyl)tetrazoles (664) are produced in the reaction of iV-aryl-diphenylketenimines Ph2C=C=NAr with hydrazoic acid/ Diethoxy disulphide, (EtO)2S2, dehydrogenates AW -dianil-inothiourea to dehydrodithizone (665). Diformazyl has been shown to be the betaine (666)/ ... 

The Schmidt reaction of carboxylic acids with hydrazoic acid has the advantage over Curtius rearrangement that it is only one step from the acid to the amine, but the conditions are more drastic (usually sulphuric acid plus sodium azide). Under these harsh conditions, the isocyanate intermediate is rarely isolated. For these reasons, the Curtius rearrangement is frequently employed to convert acids to amines. The Schmidt reaction of ketones with hydrazoic acid is a powerful method for the synthesis of amides and lactams. TTiis process is somewhat related to the Beckmann rearrangement of oximes however, the Schmidt reaction is more succinct, allowing the conversion of ketones to amides in a single operation. Considering its widespread... 

Azide ion has been shown to be an effective trap for a Beckmann intermediate. Treatment of acetophenone oxime with thionyl cloride in the presence of hydrazoic acid gave tetrazole (37), as shown in equation (23). Thiolates participate efficiendy in Beckmann reactions, and the sulW nucleophile may be incorporated into a Lewis acidic reagent, as demonstrated in equation (24). ... 

The mechanism of the Schmidt reaction has not been established with certainty. Schmidt proposed a mechanism in which the hydrazoic acid is cleaved by the strong mineral acid to nitrogen and the imide radical (NH). This radical is supposed to add to the carbonyl group, followed by a rearrangement either directly or by a Beckmann transformation of an intermediate oxime to the amide. ... 

The imides, primaiy and secondary nitro compounds, oximes and sulphon amides of Solubility Group III are weakly acidic nitrogen compounds they cannot be titrated satisfactorily with a standard alkaU nor do they exhibit the reactions characteristic of phenols. The neutral nitrogen compounds of Solubility Group VII include tertiary nitro compounds amides (simple and substituted) derivatives of aldehydes and ketones (hydrazones, semlcarb-azones, ete.) nitriles nitroso, azo, hydrazo and other Intermediate reduction products of aromatic nitro compounds. All the above nitrogen compounds, and also the sulphonamides of Solubility Group VII, respond, with few exceptions, to the same classification reactions (reduction and hydrolysis) and hence will be considered together. 

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