Oxidation with Diethyl Azodicarboxylate

Mercaptans have been oxidized with diethyl azodicarboxylate and triphenylphosphine. It is suggested that the formation of a charge-transfer complex (57) may be a key step in the reaction. 

The 3-methyl- and 3-phenyl-l,2,3-oxadiazolinium salts 96 and 97 are capable of oxidizing thiols to disulfides <1995MI817>. New dihydro-1,2,3-benzoxadiazoles, prepared by the reaction of 1,2-benzoquinones with diethyl azodicarboxylate (DEAD) or diisopropyl azodicarboxylate (DIAD) in the presence of triphenylphosphine (Section 5.03.9.4), have been shown to undergo catalytic hydrogenolysis to give phenols (Equation 12) <20050L5139>. 

The oxidation of hydrazine derivatives with diethyl azodicarboxylate is of particular interest because it involves direct hydrogen abstraction. The oxidation of keto hydrazones with lead tetraacetate leads to azoacetates, presumably by a free radical mechanism. 

The isomerization of allyl ethers to 1-propenyl ethers, which is usually performed with potassium tert-butoxide in dimethyl sulfoxide, can also be carried out under milder conditions using tris(triphen-ylphosphine)rhodium chloride,208 and by an ene reaction with diethyl azodicarboxylate,209,210 which affords a vinyl ether adduct. Removal of an O-allyl group may be achieved by oxidation with selenium dioxide in acetic acid,211 and by treatment with N-bromosuccinimide, followed by an aqueous base.201,212... 

The shortest synthesis of triquinacene is the four-step conversion from cyclo-pentadiene described by Wyvratt and Paquette (Scheme 59).351,352) Oxidative coupling of sodium cyclopentadienide with iodine generated 9,10-dihydrofulvalene (368)3S3,354) which was treated in situ with diethyl azodicarboxylate. The resulting... 

As adenosine antagonists, a great number of 8-substituted xanthines with varying substitution patterns in the 1- and 3-position have been prepared. As starting materials, l,3-dialkyl-5,6-di-aminouracils are used, which are transformed to the 1,3,8-trisubstituted xanthines by one of three methods. The first consists of condensing diaminouracil with an aldehyde to form the imine which is oxidatively cyclized by treatment with diethyl azodicarboxylate (DEAD) in a modification of a reported general procedureto give the appropriate xanthine derivative, e.g. formation of 10. 

This method is unusually mild, using neutral conditions and low temperatures (20 °C and less). It tolerates a number of functional groups in the components (e.g. acetals, esters, alkenes, etc.)- The alcohol, the carboxylic acid and triphenylphosphine are treated dropwise in an inert solvent (dichloromethane, THF, ether) with diethyl azodicarboxylate (DEAD). The ester is formed rapidly. However, tedious chromatography is frequently required to remove the by-products, triphenylphosphane oxide and hydrazo ester. The main value of the reaction lies in the clean inversion of configuration at a secondary carbinol center and in its selectivity towards primary hydroxy groups (vide infra). Inversions are usually performed with benzoic or p-nitrobenzoic acid. The benzoates are purified and saponified with aqueous base to furnish the inverted alcohols in overall yields of ca. 50%. Elimination is the main side reaction. Thus, from (44) 75% of the desired Sn2 product (45) is formed, along with 25% of the elimination product (46) (equation 19). The mechanism of the reaction has been clarified to the point that betaine (47) is the pri-... 

Their preparations copied those of their [ ]-analogues. The first method started from 2-hydrazinopurines 287 and suitable ortho esters yielding [l,2,4]triazolo-[4,3- ]purin-9-ones 288 (R2 = Aik, Aryl). Substitution of ortho esters by carbon disulfide led to 7-mercapto-derivative 288 (R2 = SH). The 7-aryl-derivatives were better accessible by the second method—the oxidative cyclization of 2-arylidenehydrazino)-derivatives 289, such as heating with diethyl azodicarboxylate, or oxidation with aerial oxygen (85CPB3113) (Scheme 82). 

The preparation of nitrosobenzene by oxidation of phenylhydroxylamine with dichromate-sulfuric acid has been described by Gattermann and Wieland.la 2,6-Dihaloanilines can be oxidized to nitroso compounds in good yield by a mixture of 30% hydrogen peroxide and glacial acetic acid.205 Nitroso compounds are also obtained in good yield by oxidation of aryl-hydroxylamines with diethyl azodicarboxylate.206... 

Table S. Oxidation of thiols to disulphides with diethyl azodicarboxylate...

Primary amines containing primary alkyl groups can be converted into aldehydes by oxidation of the triazole derivative (4) with diethyl azodicarboxylate (Scheme 1). Primary and secondary nitroalkanes can be transformed into the corresponding aldehydes and ketones either by hydrogen peroxide in aqueous methanol containing potassium carbonate" or by treatment with ceric ammonium nitrate in aqueous acetonitrile containing triethylamine. These methods offer further mild conditions as alternatives to the well known Nef reaction. 

To prepare fervenulin 4-oxides 12 or toxoflavine 4-oxides 146, it is convenient to use the reaction of l,3-dimethyl-2,4-dioxopyrimidin-6-yl hydrazone 147 or N-(3-methyl-2,4-dioxopyiimidin-6-yl) iV-methylhydrazone 148 with potassium nitrate in acetic acid [75CPB1885,76CPB338,76JCS(CC)658,82JHC1309,93CPB362]. Diethyl azodicarboxylate can be used instead of potassium nitrate [76JCS(P1 )713]. 

Acyclic ADC compounds, which are more correctly named as derivatives of diazene, are generally prepared from hydrazine derivatives. For example, diethyl azodicarboxylate (Chemical Abstracts name diethyl diazene-1,2-dicarboxylate)5 is prepared from hydrazine by treatment with ethyl chloro-formate followed by oxidation with chlorine in benzene-water.6 Other oxidants which have been used include JV-bromosuccinimide,7 nitric acid,8 inorganic nitrates,9 potassium dichromate,10 silver carbonate on celite,11 and phenyl iodosotrifluoroacetate.12 The hydrazine derivative may also be... 

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