Di-tert-butyl azodicarboxylate

Results of ab initio studies lend support to a mechanism, involving initial formation of Me3C+, CO2 and Me3C0C(0)N=N, proposed to account for oxidative fragmentation of di-tert-butyl azodicarboxylate promoted by thianthrenium perchlorate. ... 

Scheme 6.80 Typical products obtained from the 64-catalyzed enantioselective addition of a-substituted (J-keto esters to di-tert-butyl azodicarboxylate (a-hydrazination).

Dinsmore and Mercer further investigated this reaction using DBU as a base and n-Bu3P/DBAD (di-tert-butyl azodicarboxylate) as Mitsunobu s reactants, and found an unexpected steroselectivity in the Mitsunobu transformation [75b], In fact, the stereochemical course of the Mitsunobu reaction (Scheme 6.11) depended on whether the carbamic acid intermediate was N-substituted with hydrogen (retention) or with carbon (inversion). 

The a-cyanoacetates 12 are optimal substrates for the approach outlined in Scheme 2.26 due to the low pKa of the a-proton. It has been reported that the quinidine-derived alkaloid /fisocupridine (/ -ICD) can catalyze the direct a-amination of a-cyanoacetates 12 (Eq. 4) and /fdicarbonyl compounds [10], probably by an enolate having a chiral /MCD-H+ counterion as the intermediate. The a-amination of a-cyanoacetates 12 with di-tert-butyl azodicarboxylate 2c is an efficient process that proceeds with only 0.5 mol% of /MCD. The expected products 13, having a stereogenic quaternary carbon center, were isolated in excellent yields and with excellent levels of enantioselectivity independently by the nature of the aryl-substituent in the a-cyanoacetates, while the / -dicarbonyl compounds give slightly lower enantioselectivty (83-90% ee). 

Dichlorophenoxybutyric acid Dibenzylideneacetone Dibenz[a,/i]anthracene Di-tert-butyl azodicarboxylate Dibenzo-1 S-crown-b/Brj... 

The chemistry of nitrogen electrophiles R R2NX (I) was excellently summarized in 1989Ia. Recent studies in the field of stereoselective electrophilic amination, however, have shown that azidation with sulfonyl azides III, reactions with di-tert-butyl azodicarboxylate (II) and reactions with 1-chloro-l-nitroso reagents IV, are superior to the previously mentioned nitrogen electrophiles. 

The procedure outlined here160,11 closely resembles the methodology detailed in Section 7.1.1.1., except for the choice of nitrogen electrophile used, which in this case is the commercially available di-tert-butyl azodicarboxylate (DBAD). The reaction of the lithium derivatives of N-acyloxazolidinones 1 with DBAD affords diastereomerically pure (>300 1) hydrazines 2 in yields exceeding 90%1 a. 

Asymmetric electrophilic amination reactions using silyl ketene acetals 1 and di-tert-butyl azodicarboxylate (DBAD) finally lead to a-hydrazino 3 and ( )-a-amino acids 415. 

Kiankarimi, M., Lowe, R., McCarthy, J. R., Whitten, J. P. Diphenyl 2-pyridylphosphine and di-tert-butyl azodicarboxylate convenient reagents for the Mitsunobu reaction. Tetrahedron Lett. 1999,40, 4497-4500. 

The dianion of 56 reacted with di-tert-butyl azodicarboxylate ("DBAD") to furnish an 18 1 mixture (500 MHz H NMR) of anti (major)... 

Dess-Martin s reagent, 164 D-glucosamine hydrochloride, 365 di-tert-butyl azodicarboxylate ( DEAD"), 12 dianion, 453... 

Axially chiral guanidines with an external guanidine unit such as dinaphthoazepineamidine are effective catalysts for the enantioselective addition of p-oxoesters and a 1,3-diketone to di-ferf-butyl azodicarboxylates to yield cx-hydrazino-p-oxoesters and a-hydrazino-p-dike-tones in 54-99% yields and in 15-98% ee [44]. For example, stirring 2-oxocyclopenta-necarboxylate and di(tert-butyl) azodicarboxylate in THF in the presence of 0.05 mol% catalyst for four hours at —60° C provides an adduct in quantitative yield and in 97% ee (Scheme 4.15). The (R)-catalyst was prepared from (/ )-2,2 -dimethyl-3,3 -binaphthalene-diol ditriflate, 4-methoxyphenylboronic acid and 3.5-di(rert-butyl)phenylboronic acid in six steps. 

Marko and coworkers have shown that di-tert-butyl azodicarboxylate (DEAD) is a useful redox cocatalyst in combination with Cu for aerobic alcohol oxidation [25]. Overall, the conditions and reaction scope are not quite as favorable as those observed with the more recent Cu/nitroxyl systems, but primary and secondary activated and unactivated alcohols with diverse functional groups undergo effective oxidation using a catalyst consisting of (phen)CuVDBAD (Figure 6.6). 

Jorgensen et al. described a highly enantioselective amination of a-substituted a-cyanoacetates with di-tert-butyl-azodicarboxylate (DEAD) catalysed by the quinidine-derived constrained alkaloid, p-isocupreidine (p-ICPD). ° Products were isolated in excellent yield and enantioselectivity (up to >98%). The generality of the method was demonstrated by the reaction on both open-chain and cyclic p-ketoesters. Products were again obtained in up to 99% yield, but in somewhat lower ee (up to 90%). Deng... 

Isocupreidine ((3-ICD, 19), another compound in the cinchona alkaloid family, can also catalyze the a-amination of 1,3-dicarbonyl compounds enantioselectively [37]. The reaction of a-substituted 1,3-dicarbonyl compounds, including cyclic and acyclic (3-ketoesters and 1,3-diketones with di-tert-butyl azodicarboxylate, proceeded with high yield and enantioselectivity. 

More recently, Tan and co-workers reported the reaction of p,7-unsaturated thioesters with di-tert-butyl azodicarboxylate promoted by the chiral guanidine 32 as the Br0nsted base catalyst (Scheme 11.16) [57]. By judicious choice of the double bond geometry of the (3,y-unsaturated thioester compound, the reaction can deliver either enantiomeric product with excellent enantioselectivity. 

A very mild method for the preparation of isocyanates from primary amines (RNH2) and carbon dioxide (CO2) involves the use of a Mitsunobu zwitterion generated from either diisopropyl azodicarboxylate (DIAD) or di-tert-butyl azodicarboxylate and triphenylphosphine or tri-n.-butylphosphine. 

C—N Bond Formation The introdnction of a NH -group can be achieved either by reaction with A-lithiated O-methylhydroxylaniine or by azidation followed by reduction. With imines, the ami-nomethyl functionaUty is introdnced. Aiylhydrazines and benzamides are obtained by reaction with di-tert-butyl azodicarboxylate and isocyanates, respectively. 

A similar system was proposed by Marko based on CuCl, phenanthroline, di-tert-butyl azodicarboxylate (DBAD) and N-methylimidazole (NMI) as additives showing efficient oxidation of both primary and secondary alcohols to carbonyl compounds, with molecular oxygen or air as the oxidant releasing water as the sole by-product. The catal3dic system exhibits good tolerance of the presence of electron-rich alkenes, thioethers and pyridine moieties, which could be involved in other oxidation reactions but remain unaffected by the catalyst. In the case of... 

Scheme 23.55. Oxidation of primary alcohok to the corresponding aldehydes with O2 mediated by a Cn(I) catalyst in the presence of N-methyUniidazole and di-tert-butyl azodicarboxylate.

Smooth addition of phenyllithium and ort/zo-functionalized congeners takes place with di-tert-butyl azodicarboxylate (45). Acid treatment of the crude product leads directly to the deprotected hydrazine (Scheme 1-36).Analogous transformations can be accomplished also with chiral enolates instead of organolithiums. ... 

---