Diazenedicarboxylates

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

Occasionally, addition products of 4//-l,2,4-triazole-3,5-diones or diazenedicarboxylic esters and oxepins have been obtained whose formation can be rationalized by an addition to the 2,4-diene system in the oxepin, e.g. formation of 10.190191 In these cases, the primary adduct usually cannot be isolated, because it undergoes a hetero-Cope rearrangement to a tricyclic or bicyclic structure in which the oxepin oxygen has become part of a carbonyl function.190 191,227... 

The same observation can be made when 2,7-dimethyloxepin, which is known to exist almost exclusively in the oxepin form, reacts with dialkyl diazenedicarboxylates to give pyridazines ll227... 

Attempts to form a cycloadduct of cyclopent[6]azepine (10) with diethyl diazenedicarboxylate furnished the two isomeric hydrazines 14 and 15, which appear to be the products of direct electrophilic substitution of the cyclopentazepine rather than scission products of the expected [4 + 2] cycloadduct.2... 

Dimethyl diazenedicarboxylate, see Dimethyl azoformate, 1504 Dimethyldiazene, see Azomethane, 0906... 

The 1,3-dipolar cycloaddition of phosphonodithioformate. S -methanides (41) with aromatic thio ketones (42) yields 1,3-dithiolanes (43) and (44). These S-methanides are also trapped by TCNE, maleic anhydride, A-phenylmaleimide, and dimethyl diazenedicarboxylate (Scheme ll).39... 

Note that alkyl azides are potentially explosive. This and the simpler reaction conditions involved is one reason why the reaction described above is mainly carried out as a Mitsunobu reaction. In this method the alkanol is reacted with diethyl diazenedicarboxylate, triphenylphosphane and hydra-zoic acid in a one-pot reaction. The reaction also proceeds with inversion and affords the amine directly because the intermediate azide is reduced by excess triphenylphosphane in situ. 

Heathcook et al. have performed a diastereoselective aza-ene reaction using chiral di-(+)-menthyl diazenedicarboxylate 91 as the nitrogen source [54]. Compound 91 was found to react with various alkenes in the presence of 2 equiv. SnCl4, and the corresponding allylic aminated product was obtained in good yield and with de up to 42 %. The problem with this approach was the removal of the chiral menthyl ester auxiliary, which was found to be rather difficult. 

Diethyl azodicarboxylate Diazenedicarboxylic acid, diethyl ester ... 

BIS(2,2,2-TRICHLOROETHYL) AZODICARBOXYLATE [Diazenedicarboxylic acid, bis(2,2,2-trichloroethyl) ester]... 

Except for 12 and 13 b-d, the isolation of the amidine tautomer has been reported only recently. Spectral data show that alkylated 1,1-enediamines such as 16 tautomerize predominantly to 4,5-dihydroimidazole derivatives 16 3 6 (equation 4). More interestingly, the adducts of enediamines and diethyl diazenedicarboxylate exist exclusively as the enediamine tautomer when R2 = H (17) and as the amidine tautomer when R2 = Et (17 )37 (equation 5). Since 17 and 17 differ only in an ethyl group, it appears that the steric effect plays an important role in determining the tautomeric equilibrium. 

Acetyl-4,6-dimethoxyphenyl)-l, 2-hydrazinedicarboxylic acid bis(2,2,2-trichloroethyl) ester 1,2-Hydrazinedicarboxyiic acid, l-(2-acetyl-4,6-dimethoxyphenyl)-, bis(2,2,2-lrichloroethy ) ester (13) (154876-13-8) Trifluoromethanesulfonic acid Methanesulfonic acid, trifluoro- (8,9) (1493-13-6) Bis(2,2,2-trichloroethyl) azodicarboxylate Diazenedicarboxylic acid, bis(2,2,2-trichloroethyl) ester (9) (38857-88-4)... 

When allylic hydrogens are present in the alkene, A-allyl hydrazine derivatives are formed preferentially by the ene reaction (Section 7.6.). Furthermore, the reaction of styrenes, (Ey -phenylpropene, and stilbenes with diazenedicarboxylates (traditionally known as azodicar-boxylates) and triazolediones affords products involving double Diels-Alder or Diels-Alder-ene reactions (Section 7.2.10.3.3.). 

In the reactions of dimethyl and diethyl diazenedicarboxylate with electron-rich alkenes the diazetidine/oxadiazine ratio is dependent on the structure (cyclic, acyclic), the substitution pattern (1,1- or 1,2-disubstituted) and the geometry of the alkene. 

Reaction of aryl vinyl ethers, however, invariably gives mixtures of diazetidines and oxadiazines. The ratio is mainly dependent on the nature of the substituent on the phenyl group and, in part, on the nature of the alkyl group of the dialkyl diazenedicarboxylate and the solvent substituents which enhance the nucleophilicity of the alkene and the electrophilicity of the diazene, and polar solvents that favor a polar mechanism, result in concurrent formation of the diazetidine as the predominant product and vice versa15, l< Similarly, diazetidines 7 and oxadiazines 8 are formed in comparable yields in the reactions of vinyl sulfides with dimethyl diazenedicarboxylate, the ratio is principally dependent on the nature of the sulfur substituent (aryl, alkyl)17. 

Acyclic enamines give diazetidines with dimethyl diazenedicarboxylate, e.g., formation of 9. when hydrogen abstraction and ene reaction can be suppressed18, but from the less nucleophilic A -vinylpyrrolidinone the oxadiazine 10 is obtained16. 

The diazetidine was obtained by the reaction of 4-methyl-3//-l,2,4-triazole-3,5(4//)-dione with bisadamantylidene21 23 and dibenzobarrelene25. Products 15 derived from skeletal rearrangement, in competition with the ene reaction, are obtained in the reaction of 13, and sometimes diazenedicarboxylates, with strained bicyclic alkenes 6,26-28 and monoterpenes29. 

Cyclohexadiene reacts with diazenedicarboxylates and triazolediones to give ene-type products as the primary products, whereas bicyclic 1,4-dienes, e.g., norbornadiene derivatives, give homo-Diels-Alder adducts 96-37-39. However, if a longer tether links C-l and C-4 of the... 

The most commonly employed diazenes, e.g., diethyl, bis(2,2,2-trichloroethyl), and di-/m-butyl diazenedicarboxylate, and 4-phenyl-3/7-1,2,4-triazole-3,5(4/7 )-dione, are commercially available. However, various new reagents or methods recently introduced for the preparation of specific diazenes from hydrazines can be successfully applied to other hydrazines. Especially important is the development of chemoselective methods for converting hydrazines to diazenes in the presence of unsaturated substrates, for example in intramolecular cycloaddition reactions (Section 7.2.10.3.10.2.), where either the (di)ene group and other functions present in the substrate are sensitive to the (oxidizing) reagent employed. 

Dialkyl diazenedicarboxylates are usually isolated after oxidation of the corresponding hydrazines. 

Since (Z)-diazenes are more reactive than ( fi)-diazenes in Diels-Alder reactions, the cycloaddition of ( )-diazenes, e.g., diazenedicarboxylates, is accelerated by UV irradiation which causes E/Z isomerization of the diazene1. 

The adduct of furan and dibenzoyldiazene, previously assigned a diazetidine structure9, is instead an oxadiazine 1010. Furans, however, act as dienes in [4 + 2] cycloaddition reactions with dialkyl diazenedicarboxylates to give unstable adducts. 

The geometry of the double bond of (i )-l,2-dimethoxvethylene is preserved in the product trans-16 of the two-step cycloaddition with dimethyl diazenedicarboxylate, even though the reaction proceeds through an intermediate having dipolar character. However, partial loss of the alkene geometry is observed in the products 16 of the cycloaddition performed on the (Z)-isomer13. 

A solution of 1.25 g (8.5 mmol) of dimethyl diazenedicarboxylate in 3 mL of benzene is added dropwise at 20 C to 1.0 g (11 mmol) of (/3)-1,2-dimethoxyethylene in 3 mL of benzene. The reaction mixture is almost colorless after 30 min. On standing overnight a precipitate appears. All volatile material is removed under reduced pressure. The residue (2.0 g. 100%). mp 126 128 C is pure oxadiazine within the limit of H NMR. Reeryslalli7ation from ben/ene/hexane raises the mp lo 128-130 C... 

The reaction of norbomene with diethyl and diphenyl diazenedicarboxylate and dibenzoyl-diazene gives e.vo-oxadiazines 1 with unspecified yields25. The absence of rearranged products was assessed by experiments on 2,3-dideuterionorbornene. However, at least three other unidentified products were observed in the crude reaction mixture obtained with diethyl diazenedicarboxylate26. 

The reaction of norbornadiene with diethyl diazenedicarboxylate affords a mixture of two 1 1 adducts 2 and 3 in approximately equal amounts25 one of the adducts 3 is produced by homo-Diels-Alder cycloaddition, as demonstrated by further conversion to quadricyclene, and the other is the oxadiazine 2, not previously identified. 

Dialkyl diazenedicarboxylates do not undergo efficient cycloaddition with vinyl ethers. For example the [2 -I- 2] adduct was obtained in low yield from the cyclopropane-fused dihydropy-ran 11 even at high temperature28. From the same substrate the [2 + 2] cycloadduct with 4-phenyl-3//-1,2,4-triazole-3,5(4//)-dione was obtained quantitatively even at low temperature through a polar mechanism involving an aziridinium imide as the intermediate28. 

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