Azodicarboxylic acid ester adducts

Without additional reagents Azodicarboxylic acid ester adducts 1-Aminohydrazines from tert. amines... 

Azodicarboxylic acid ester adducts Hydrazines by substituting addition... 

The cycloadducts 257 of esters of azodicarboxylic acid to 2,7-dimethyloxepin undergo a spontaneous Claisen rearrangement to form the dihydrocyclopropapyridazines 258 (equation 139)132. Homofulvenes 259 (R1, R2 = HorMe) react with dimethyl azodicarboxylate to form rearranged adducts 260 (equation 140)133. 

In common with other azodicarboxylic acid derivatives, the uses of 4-phenyl-l,2,4-triazoline-3,5-dione are many. It undergoes a Diels-Alder reaction with most dienes11-14 and is, in fact, the most reactive dienophile so far reported.15 16 As with the formation of all Diels-Alder adducts the reaction is reversible, and in the case of the adduct with 3-j3-acetoxy-17-cyano-5,14,16-androstatriene, the reverse reaction can be made to proceed under especially mild conditions.14 An instance has also been reported of the dione photochemically catalyzing other retro Diels-Alder reactions.17 Along with the proven use of azodicarboxylic ester,18-18 the dione should be potentially important in the preparation of strained ring compounds. 

Scheme 6.81 Transformation of one adduct prepared from the 64-catalyzed asymmetric addition of a-substituted P-keto esters to di-tert-butyl azodicarboxylate (a-hydrazination) into the corresponding oxazolidinone amino acid derivative.

Thiolesters. These esters are easily obtained by addition of an alcohol and then t h iolacetic acid to the preformed adduct of P(C6H 5)3 and diisopropyl azodicarboxylate in THF (equation I). The reaction is accompanied by inversion of configuration.5... 

In the methodology developed by Oppolzer and Moretti18, closely resembling the Gen-nari, Colombo and Bertolini procedure15, the crude ketene silyl acetals 7, derived from the chiral esters 6, are reacted with di-tm-butyl azodicarboxylate (DBAD) to yield the adducts 8, and, via 9, the amino acids 10. 

Use of cyclopentene, frans-hex-3-ene and frans-oct-4-ene afforded the ene adducts in good yield with a diastereomeric excess of 86 14 in each case. The diastereoselectivity observed using di-(—)-( / ,25)-2-phenyl-l-cyclohexyl diazenedicarboxylate as a chiral azo-enophile offered a significant improvement over the use of di-(-)-menthyl azodicarboxylate where the level of asymmetric induction achieved in Lewis acid-mediated ene reactions with simple alkenes was not impressive. Moreover, it proved difficult to cleave the N-N bond in the menthyl ester azo-ene adducts whereas sodium/liquid ammonia was used to smoothly cleave the N-N bond in the diacylhydrazine adducts formed using di-(—)-(l/ ,25)-2-phenyl-l-cyclohexyl diazenedicarboxylate as azo-enophile. 

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