Azodicarboxylic acids diethyl ester

Diethyl azodicarboxylate Formic acid, azodi-, diethyl ester (8) Diazenedicarboxylic acid, diethyl ester (9) (1972-28-7)... 

Diethyl azodicarboxylate Diazenedicarboxylic acid, diethyl ester ... 

An interesting alternative in using diols, but starting from 3,4-dihydroxythiophene-2,5-dicarboxylic acid diethyl ester (the same intermediate as used in the Gogte pathway above), was developed independently by the groups of Reynolds [25] and Bauerle [26], who utilized the Mitsunobu reaction with azodicarboxylic acid ester-phosphane as the etherification agent. 

Cydization of P-hydroxy-a-amino esters under Mitsunobu reaction conditions is an alternative approach to aziridine-2-carboxylic esters [6b, 13-16], In this case the P-hydroxy group is activated by a phosphorus reagent. Treatment of Boc-a-Me-D-Ser-OMe 13 (Scheme 3.5) with triphenylphosphine and diethyl azodicarboxylate (DEAD), for example, gave a-methyl aziridinecarboxylic acid methyl ester 14 in 85% yield [15]. In addition to PPh3/DEAD [13b, 15], several other reagent combi-... 

In a 1-1., three-necked, round-bottomed flask equipped with a constant-pressure dropping funnel, a mechanical stirrer, and a reflux condenser is placed 174 g. (1.0 mole) of ethyl azodicarbox-ylate in 150 ml. of ether. Freshly prepared cyclopentadiene (70 g., 1.06 moles) is added dropwise over a 1-hour period to the stirred ethereal solution of diethyl azodicarboxylate. During the addition a gentle reflux is maintained by external cooling with an ice-water bath as needed. When the addition is complete, the reaction mixture is allowed to stand for 4 hours, or less if the yellow color of the azodicarboxylic acid ester disappears. I he dropping funnel and condenser are replaced by a glass stoj)pcr and a short distillation head, respectively. The ether and unreactcd diene are distilled off on a steam bath and the... 

We were not able to obtain any cycloadduct from unactivated 2-azadienes 139 and esters of acetylenedicarboxylic acid. However, we found that 139 did cycloadd to typical electron-poor dienophiles such as esters of azodicarboxylic acid and tetracyanoethylene (Scheme 62). Thus, diethyl and diisopropyl azodicarboxylates underwent a concerted [4 + 2] cycloaddition with 139 to afford in a stereoselective manner triazines 278 in 85-90% yield (86CC1179). The minor reaction-rate variations observed with the solvent polarity excluded zwitterionic intermediates on the other hand, AS was calculated to be 48.1 cal K 1 mol-1 in CC14, a value which is in the range of a concerted [4 + 2] cycloaddition. Azadienes 139 again reacted at room temperature with the cyclic azo derivative 4-phenyl-1,2,4-triazoline-3,5-dione, leading stereoselectively to bicyclic derivatives 279... 

When esterification is achieved under the Mitsunobu conditions (diethyl azodicarboxylate, Ph3P), only esters at positions 6 and 6 are produced, and isolation of the 6-monoester, which is formed faster is possible. Thus diesters can be efficiently prepared.97 99 In this type of reaction, when the carboxylic acid is... 

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-... 

The reaction of iV-methyl tertiary alkylamines with diethyl azodicarboxylate is known (61) to result in the formation of an intermediate hydrazodiester (116), which on acid hydrolysis gives the corresponding secondary amine together with hydrazine 1,2-dicarboxylate diethyl ester and formaldehyde... 

Tetrafluoroethylene and diethyl azodicarboxylate yield diethyl 3,3,4,4-tetrafluoro-l,2-diazetidine-l,2-dicarboxylate on heating. This reaction has been further investigated using other esters, and also with other fluoro-olefins, CF CFH, CF iCF-CFs, and CF CFC1. Di-isopropyl ester (79) is hydrolysed by concentrated sulphuric acid at room temperature to 3,3,4,4-tetrafluoro-l, 2-diazetidine (80). 

One of the most widely used procedures for dehydrative coupling and cyclization reactions is the Mitsunobu reaction in which the components are treated with triphenylphosphine and diethyl azodicarboxylate (DEAD, EtOaC—N=N—COiEt). The overall equation for reaction of an alcohol 67 with an acid 68 to form the ester 69 is as shown and the active species is the zwitterionic... 

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