Tert azodicarboxylate

Kinetic studies on the reaction of azodicarboxylates with cyclopentadiene have shown that the dimethyl ester, DMAZD, reacts 5 -6 times more rapidly than DEAZD.51 The bulky tert-butyl ester (2, R = r-Bu) reacted only slowly with cyclopentadiene.7 The reaction proceeds faster in polar than in nonpolar... 

Wang resin was purchased from Advanced ChemTech (1% DVB, 0.70mmol/g substitution, 100-200 mash, Cat. SA5009). Anhydrous tetrahydrofuran (THF), A/A-dimcthyl-formamide (DMF), methanol, dichloromethane, pyridine, 1,1 -carbonyldiimidazole (CDI), piperazine, homopiperazine, trans-1,4-diaminocyclohexane, 4-(dimethylamino)pyridine (DMAP), succinic anhydride, diglycolic anhydride, 3-methyl-glutaric anhydride, 2-aminophenol, 2-amino-p-cresol, 2-amino-4-tert-butyl phenol, /V-methylmorpholine (NMM), triphenylphosphine, diethyl azodicarboxylate (DEAD), and trifluoroacetic acid (TFA) were purchased from Aldrich Chemical Company, Inc. and used without further purification. PyBOP was purchased from Novabiochem. 

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).

The isomerization of allyl ethers to 1-propenyl ethers, which is usually performed with potassium tert-butoxide in dimethyl sulfoxide, can also be carried out under milder conditions using tris(triphen-ylphosphine)rhodium chloride,208 and by an ene reaction with diethyl azodicarboxylate,209,210 which affords a vinyl ether adduct. Removal of an O-allyl group may be achieved by oxidation with selenium dioxide in acetic acid,211 and by treatment with N-bromosuccinimide, followed by an aqueous base.201,212... 

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). 

Synthesis of (-I-) calanolide A (Scheme 8-11) was achieved by enzyme catalyzed resolution of the aldol products ( )-53. Compound 7 with acetaldehyde by aldol reaction in the presence of LDA/TiCU stereoselectively produced a mixmre of ( )-53 and ( )-54 (94% yield), the ratio of which was 96 4. ( )-53 was then resolved by lipase AK-catalyzed acylation reaction in the presence of tert-butyl methyl ether and vinyl acetate at 40 °C to obtain 41% yield of (+)-55 and 54% yield of the acetate (—)-56. Mitsunobu cyclization of (+)-55 in the presence of tri-phenylphosphine and dielthyl azodicarboxylate afforded 63% yield of (-l-)-43 with 94% ee as determined by chiral HPLC. Luche reaction on (+)-43 with CeCla 7H2O and triphenyl phosphine oxide and NaBH4 in the presence of ethanol at 30 °C gave the crude product. It was purified by column chromatography on silica gel to give 78% yield of a mixture containing 90% of (+)-calanolide A and 10% (+)-calanohde B, which were further separated by HPLC. 

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. 

Abbreviations Ac, acetyl AIBN, 2,2 -azobisisobutyronitrile All, allyl Alloc, allyloxycarbonyl Bn, benzyl BOM, benzyloxymethyl BPC, p-phenylbenzoyl Bu, butyl t-Bu, tert-butyl Bz, benzoyl CAN, ammonium hexanitratocerate (IV) Cbz, bezyloxycarbonyl CDl, carbonyldiimizazole ClAc, chloroacetyl Cp, cyclopentadienyl CSA, DL-lO-camphorsulfonic acid DABCO, l,4-diazabicyclo[2.2.2]octane DAST, diethylaminosulfur trifluoride dba, dibenzylideneacetone DBU, l,8-diazabicyclo[5.4.0]undec-7-ene DCC, iV,iV-dicyclohexylcarbodiimide DDQ, 2,3-dichloro-5,6-dicyano-l,4-benzoqui-none DEAD, diethyl azodicarboxylate DEIPS, diethylisopropylsilyl DIBAL, diisobutylaluminum hydride DMAP,... 

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... 

Theil et al. developed a method for chemoenzymatic synthesis of both enantiomers of cispentacin [89]. frans-2-Hydroxymethylcyclopentanol, obtained by the sodium borohydride reduction of ethyl 2-oxocyclopentanecarboxylate, was monosilylated with tert-butyldimethylsilyl (TBDMS) chloride to afford 55. Lipase PS-catalysed transesterification with vinyl acetate in /erf-butyl methyl ether furnished the ester 56 and the alcohol 57. The deacetylated 58 was obtained by the Mitsunobu reaction with phthalimide, triphenylphosphine and diethyl azodicarboxylate (DEAD) to furnish the cis oriented 59 with inversion of configuration (not retention as mentioned in the original article) (Scheme 9). Desilylation, Jones oxidation and subsequent deprotection with aqueous methylamine gave the ( R,2S) enantiomer 5 [89]. The (15, 2/f) enantiomer was prepared by the same route from the silyl alcohol 57. 

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). 

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