Diethyl diazodicarboxylate

Reaction of (96) with ketoacetylenes (101) occurs by 1,4-addition of the thiol to the acetylene to give (102) (Equation (36)) <88JOUi94i >. Similar results were obtained with (98) <92CHE222, 92CHE795) and with 3-methyl-5-triazolinethione <91JHC325>. Diethyl diazodicarboxylate oxidised 3-methyl-5-triazolinethione to the bis(3-methyltriazolyl)disulfide (103) <91JHC325>. 

Aminoquinoxaline reacts with hydroxylamine hydrochloride to give 2-(hydroxyimino)-l,2-dihydroquinoxaline (140), also formed by dehydrogenation of 2-(hydroxyimino)tetrahydroquinoxaline (32) with diethyl diazodicarboxylate.148... 

LACTAMS Benzenesulfenyl chloride. Pentacarbonyl(methoxyalkyl)chromium carbenes. Triphenylphosphine-Diethyl diazodicarboxylate. 

The Mitsunobu reaction is used to convert an alcohol and an acid into an ester by formation of an activated alcohol (PhsP, diethyl diazodicarboxyl-ate), which then undergoes displacement with inversion by the carboxylate. Although this reaction works very well, it suffers from the fact that large quantities of by-products are produced, which generally require removal by chromatography. 

Scheme 3.23 The Mitsunobu reaction with fluorous condensation reagents [24] enables the simple purification of the reaction product and recycling of the reagents TPP (49) and DEAD (52). ( TPP = fluorous triphenylphosphine TPPO = fluorous triphenylphosphine oxide DEAD = fluorous diethyl diazodicarboxylate DCEH = fluorous dicarboxyethoxyhydrazine).

The use of unsubstituted 2-vinylindoles also tends to be complicated by their limited stability, although this problem can be diminished by use of EW groups on nitrogen <7lJOCl759>. There are cases, such as with diethyl diazodicarboxylate, where electrophilic substitution at C3 competes with cycloaddition <88H(27)1253>. 

On the other hand methyl penicillinate which lacks the side-chain was readily transformed into the corresponding azetidine 110 diborane reduction gave 109 which cyclised under acidic conditions with diethyl diazodicarboxylate and triphenylphosphine [66] (Scheme 36). The carboxylate 111 is a very weak p-lactamase inhibitor. 

Sn2 inversion of an alcohol by a nucleophile using disubstituted azodicarboxylates (originally, diethyl diazodicarboxylate, or DEAD) and trisubstituted phosphines (originally, triphenylphosphine). 

The overall acceptance of hydrogen by a reducing reagent is demonstrated by item 10 of Table 8.5. Here, the diethyl ester of diazodicarboxylic acid (diethyl azodi-carboxylate [DEAD]) serves to oxidize 1-phenylpropanol to phenylpropanone while it is reduced to diethyl hydrazo-dicarboxylate in the process. Although the details are sketchy, a possible pathway is shown in Scheme 8.7. 

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