Decomposition azodicarboxylates

Reduction by diimide can be advantageous when compounds contain functional groups that would be reduced by other methods or when they are unstable to hydrogenation catalysts. There are several methods for generation of diimide and they are illustrated in Scheme 5.4. The method in Entry 1 is probably the one used most frequently in synthetic work and involves the generation and spontaneous decarboxylation of azodicarboxylic acid. Entry 2, which illustrates another convenient method, thermal decomposition of p-toluenesulfonylhydrazide, is interesting in that it... 

Since diimide exists as a transient intermediate and cannot be isolated under normal conditions, procedures for reduction by diimide necessarily involve generation of the reagent in situ1 1 11. Diimide can be generated by (i) oxidation of hydrazine, (ii) acid decomposition of azodicarboxylate salts and (iii) thermal or base-catalyzed decomposition of substituted benzenesulfonyl hydrazides. 

Diethyl azelate, 45, 31 Diethyl azodicarboxylate, reaction with cyclopentadiene, 49,1 Diethylbenzene as solvent for decomposition of diphenyIiodonium-2-carboxylate in preparation of... 

Diimide diimine, diazene), N2H2 or HN=NH, is an ephemeral species which results from decomposition with acids of potassium azodicarboxylate [264, 265] from thermal decomposition of anthracene-9,10-diimine [266, 267], and of hydrazine [268,269] and its derivatives [270]. Although this species has not been isolated, its transient existence has been proven by mass spectroscopy and by its reactions in which it hydrogenates organic compounds with concomitant evolution of nitrogen [271]. 

Photolysis of azirine (297), or thermolysis of the oxazaphosphole (298), affords reactive azomethines (299) and (300), respectively. These react with azodicarboxylates to give triazolines (301) and (302) as in Scheme 132 (74HCA1382, 73CB3421). The use of diaziridine (303) to afford the triazolidinone (304) in Scheme 133 (74JOC3198) may be compared with the reaction shown in Scheme 131. Thermal decomposition of the aziridine (305) proceeds via an ylide (306) which reacts with azodicarboxylate to afford the triazolidine (307) in very good yield (Scheme 134) (66JOC3924). For similar uses of ylides see (81HC(37)1, p. 516). 

Recently some aromatic aldehydes have been treated with diimine under standardized conditions, the reagent being produced by decomposition of potassium azodicarboxylate in methanol in almost all cases high yields of alcohol were obtained.419... 

Foaming with dry gases generated by the thermal decomposition of a dihydro-oxadiazinone + azodicarboxylic acid amide or ester PPE-polyolefin graft copolymer and NBR Epoxy-terminated liquid PB, with either PP-MA or SEBS SBR and SBS copolymer ABS and SAN Hydroxynaphthoic acid... 

Foaming with dry gases generated by the thermal decomposition of a dihydro-oxadiazinone + azodicarboxylic acid amide or ester Kochanowski 1982... 

Alkyl- and aryl carbodiimides can be prepared under mild conditions from thioureas with diethyl azodicarboxylate/triphenylphosphine (Mitsunobu reagent), typically in yields of around 80% the by-products are triphenylphosphine sulfide and diethyl hydrazodicarboxylate [1278]. The active intermediate in this system is the betaine 1739, which is formed from diethyl azodicarboxylate (DEAD) and triphenylphosphine. Driven by its charge distribution and its chalcogenophilicity, 1739 reacts with the thiourea 1740 to form the P,S bond in 1741. This energy-rich molecule stabilizes by decomposition into three molecules, namely the two byproducts, triphenylphosphine sulfide and diethyl hydrazodicarboxylate, and the desired carbodiimide 1699. Diphenylcarbodiimide 1699 (R = R = Ph) was prepared from N,N -diphenylthiourea 1740 (R = R = Ph) with DEAD and triphenylphosphine in 65% yield [1278]. 

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