Reaction of N-arylcarbamoyl-1,4-benzoquinone imines with sodium azide

N-Arylcarbamoyl-1,4-benzoquinone imines reacted with sodium azide in completely regioselective fashion according to the 1,4-addition pattern with formation of 1-(3-azido-4-hydroxyphenyl)-3-arylureas. The reaction of N-arylcarbamoyl-2,6-dichloro-3,5-dimethyl-1,4-benzoquinone imines with sodium azide afforded N-arylcarbamoyl-2,6-diazido-3,5-dimethyl-1,4-benzoquinone imines as a result of nucleophilic substitution of the chlorine atoms.     

Reaction of some <Emphasis Type="Italic">N</Emphasis>-substituted 1,4-benzoquinone imines with sodium azide

The reactions of N-(arenesulfinyl)-1,4-benzoquinone imines with sodium azide afforded the corresponding N-(arylsulfanyl)-2-azido-1,4-benzoquinone imines via 1,4-addition of azide ion and subsequent intramolecular oxidation–reduction.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-sulfonyl-1,4-benzoquinone imines with sodium azide

Depending on the conditions and the order of addition of the reactants, reactions of N-sulfonyl-1,4-benzoquinone imines with sodium azide afforded N-(3-azido-4-hydroxyphenyl)alkane(arene)sulfonamides, N-(3-azido-4-oxocyclohexa-2,5-dienylidene)alkane(arene)sulfonamides, and N-(3,5-diazido-4-hydroxyphenyl)-alkanesulfonamides. Quantum chemical calculations showed that the reactions begin with addition of azide ion to the quinone imine.     

Synthesis of N-linked glycan derived from Gram-negative bacterium, Campylobacter jejuni

Recent research has revealed the presence of asparagine (Asn)-linked (N-linked) glycoproteins in certain prokaryotes. In this paper, we describe the chemical synthesis of a novel N-glycan derived from Campylobacter jejuni, a heptasaccharide composed of Asn-linked bacillosamine (Bac), repeating GalNAc, and branching Glc, namely GalNAc-α(1,4)-GalNAc-α(1,4)-[Glc-β(1,3)-]GalNAc-α(1,4)-GalNAc-α(1,4)-GalNAc-α(1,3)-Bac. The synthesis started from a Bac-acceptor, which was consecutively glycosylated with 4-O-pentafluoropropionyl (PFP) protected donors to give heptasaccharide. Reduction of azide groups was followed by debenzylation to complete the synthesis of the target oligosaccharide.     

Ru(II)-catalyzed α-sulfonamidation of cyclic β-ketoesters with sulfonyl azides

α-Sulfonamidation of β-ketoesters with sulfonyl azide has been developed for the first time using a catalytic amount of Ru(II) complex to produce the 1-oxo-2-(sulfonamido)-2,3-dihydro-1H-indene-2-carboxylate and 1-oxo-2-(sulfonamido)-1,2,3,4-tetrahydronaphthalene-2-carboxylate derivatives in good yields. This method also works well with α-iodotetralones to afford the N-(1,4-dioxo-1,4-dihydronaphthalen-2-yl)sulphonamide derivatives under similar conditions.     

Novel and efficient synthesis of triazolobenzodiazepine analogues through the sequential Ugi 4CR-click-N-arylation reactions

An efficient approach for the synthesis of N-alkyl-2-aryl-2-(6-oxo-4H-benzo[f][1,2,3]triazolo[1,5-a][1,4]diazepin-5(6H)-yl)acetamides is described. The protocol involves Ugi four-component reaction of 2-bromobenzoic acid, propargylamine, aldehydes and isocyanides followed by in situ sequential click reaction of azide ion with triple bond and N-arylation reaction to afford desired products in good to excellent yields.     

Synthesis of N-propynyl analogues of peptide nucleic acid (PNA) monomers and their use in the click reaction to prepare N-functionalized PNAs

Application of the click reaction for coupling a 2-(2-aminoethoxy)ethoxy (AEE) function to thyminyl, cytosinyl and adeninyl peptide nucleic acid (PNA) monomer analogues bearing a N-propynyl group, in place of the original N-2-aminoethyl moiety, has been explored. The N-propynyl PNA analogues were prepared from glycine ethyl ester hydrochloride and the structure of the thyminyl derivative was confirmed by X-ray diffraction. These monomers were employed in click reactions with Boc-protected AEE azide to afford the corresponding triazolyl-linked PNA-AEE conjugates in yields ranging from 64 to 76%. [1,4]-Regiochemistry was verified from a NOESY correlation experiment.     

6-Azido d-galactose transfer to N-acetyl-d-glucosamine derivative using commercially available β-1,4-galactosyltransferase

A new strategy to tag glycoproteins carrying terminal GlcNAc was developed using commercially available bovine β-1,4-galactosyltransferase (GalT) and UDP-6-azidogalactose. The azide function was then allowed to react via a biotinylated Staudinger-Bertozzi probe demonstrating the usefulness of such a procedure to tag any glycoprotein possessing a N-acetylglucosamine terminal residue from any type of cell lysate.     

Reactions of N-substituted 2,6(3,5)-dialkyl-1,4-benzoquinone imines with arenesulfinic acids

The regioselectivity in the reactions of N-arylsulfonyl-2,6-dialkyl-1,4-benzoquinone imines with arenesulfinic acids (1,6-, 6,1-, or 6,3-addition) is determined by steric factor, while in the reactions of N-aroyl-1,4-benzoquinone imines electronic effect of substituents in the quinoid ring is crucial. The reactions of N-arylsulfonyl-3,5-dimethyl-1,4-benzoquinone imines with arenesulfinic acids follow mainly the 1,4-addition pattern. N-(N-Arylsulfonylbenzimidoyl)-1,4-benzoquinone imines are capable of reacting in a way similar to both N-arylsulfonyl and N-aroyl derivatives.     

Synthesis of amino-1,4-anhydro-d-pentitols and amino-1,5-anhydro-d-hexitols with the arabino configuration from (R)-glycidol

2-Amino-1,4-anhydro-pentitol and 3-amino-1,5-anhydro-4-deoxy-hexitol with the arabino configuration were synthesised from (R)-glycidol using a metathesis reaction as the key step. The dihydrofuran or dihydropyran products obtained after the metathesis reaction were subjected to epoxidation, epoxide opening with azide anion and finally azide reduction.     

Investigation of electrochemically induced Michael addition reactions. Oxidation of some dihydroxybenzene derivatives in the presence of azide ion

In aqueous solution containing azide ion as a nucleophile, electrochemical oxidation of hydroquinone and some dihydroxybenzoic acids have been studied using cyclic voltammetry and controlled-potential coulometry. The voltammetric data show that electrochemically generated para and ortho-benzoquinones participate in Michael addition reactions with azide ions to form the corresponding diazido or diaminobenzoquinones. In this work, we have proposed various mechanisms for the electrode process and we report an efficient and one-pot method for the synthesis of 2,5-diazido-1,4-benzoquinone, 2,5-diamino-1,4-benzoquinone, 4,5-diamino-1,2-benzoquinone, and 2,3-diamino-5,6-dioxocyclohexa-1,3-dienecarboxylic acid based on the Michael reaction of electrochemically generated ortho and para-benzoquinones with azide ion in an undivided cell using an environmentally friendly reagent-less method in ambient conditions. An estimation of the observed homogeneous rate constant (k_obs) of the reaction of electrochemically generated para-benzoquinone with azide ion by the digital simulation method is also presented.     

Reaction of N-acyl-and N-[N-arylsulfonylbenz(acet)imidoyl]-1,4-benzoquinone monoimines with hydrazoic acid

N-Aroyl-3,5-dimethyl-and N-[N-arylsulfonylbenz(acet)imidoyl]-3,5-dimethyl-1,4-benzoquinone monoimines react with hydrazoic acid according to the 1,4-addition pattern. N-Acyl-2,3,5,6-tetrachloro-1,4-benzoquinone monoimines take up hydrazoic acid at the double C=N bond (1,2-addition).     

Synthesis of N,N′-bis[4-(1H-1,2,3-triazol-1-yl)furazan-3-yl]-methylenediamine derivatives

[3+2] Cycloaddition of azide groups of N,N′-bis(4-azidofurazan-3-yl)methylenediamine to 1,3-dicarbonyl compounds and malonodinitrile was shown to proceed regioselectively with the formation of the corresponding N,N′-bis[4-(1H-1,2,3-triazol-1-yl)furazan-3-yl]methylenediamine derivatives. The reactions of N,N′-bis(4-azidofurazan-3-yl)methylenediamine with cyanoacetic acid ethyl ester and amide led to the formation of the product of transformation of the azide group in the starting compound to the amino groups.     

A facile and one-pot synthesis of N-Fmoc/Bsmoc/Boc/Z-protected ureidopeptides and peptidyl ureas employing diphenylphosphoryl azide [DPPA]

Diphenylphosphoryl azide (DPPA) mediated one-pot synthesis of N^α-Fmoc/Bsmoc/Boc/Z-protected ureidopeptides and peptidyl ureas as well as phenyl/succinimidyl (N^α-urethane protected) methyl carbamates starting from N^α-protected amino acids is reported. The formation of an azide, its rearrangement and coupling with an amino component is accomplished in a sequence of one-pot operations. The protocol has incorporated urea linkages in a sterically hindered peptide.     

Highly enantioselective (OC)Ru(salen)-catalyzed sulfimidation using N-alkoxycarbonyl azide as nitrene precursor

Enantioselective imidation of alkyl aryl sulfides with N-alkoxycarbonyl azide as a nitrene precursor was effected by using (OC)Ru(salen) complex 1 as catalyst. The steric and electronic nature of the N-alkoxycarbonyl group was found to strongly affect the enantioselectivity and the reaction rate, and high enantioselectivity (up to 99% ee) and good chemical yields were achieved by using 2,2,2-trichloro-1,1-dimethylethoxycarbonyl azide as the nitrene precursor at room temperature.     

Synthesis of N-arylcarbamates with tetrazole fragment and some their derivatives

Reactions of methyl(ethyl) N-(2-cyanophenyl)carbamates with sodium azide in dimethylformamide at 80–90°C in the presence of anhydrous CdCl₂ afforded the corresponding N-arylcarbamates with a 1,2,3,4-tetrazole fragment. The acylation of methyl N-[2-(1H-1,2,3,4-tetrazol-5-yl)phenyl]carbamate with acetic anhydride followed by the condensation of the obtained N-acyl derivative with thiophene-2-carbaldehyde in the KOH methanol solution led to the formation of methyl N-(2-{1-[3-(2-thienyl)-2-propenoyl]-1H-1,2,3,4-tetrazol-5-yl}phenyl)carbamate. The reaction of cyclohexyl N-(4-aminophenyl)carbamate with a triethyl orthoformate and sodium azide in glacial AcOH yielded cyclohexyl N-[4-(1H-1,2,3,4-tetrazol-1-yl)phenyl]carbamate.     

New access to azido-substituted alkylnitramines

A new versatile access to azido-substituted N-alkylnitramines is based on ring opening in N-nitrooxazolidines and N-nitroperhydro-1,3-oxazines with thionyl chloride followed by treatment with sodium azide. Representative N,N-bis(azidoalkyl)- and N-azidoalkyl-N-methoxymethyl- containing nitramines were synthesized and characterized.     

Synthesis of new mono-N-tosylated diamine ligands based on (R)-(+)-limonene and their application in asymmetric transfer hydrogenation of ketones and imines

A synthetic procedure leading to the preparation of a new family of enantiopure mono-N-tosylated-1,2-diamines derived from (R)-(+)-limonene is described. (+)-Limonene was transformed into the appropriate N-tosyl derivative using N-tosylaziridination based on chloramine-T trihydrate. Subsequent ring opening by sodium azide afforded the corresponding isomeric azides. Finally, reduction of the azide function gave enantiomerically pure mono-N-tosylated-1,2-diamines. The ligands obtained proved to be effective in the asymmetric transfer hydrogenation protocol on aromatic ketones and imines.     

Reaction of N-arylsulfonyl-2(3)-arylsulfonylamino-substituted 1,4-benzoquinonimines with sodium arylsulfinates

N-Arylsulfonyl-3-arylsulfonylamino-substituted 1,4-benzoquinonimine reacts with sodium arylsulfinates regiospecifically along 1,4-addition scheme; N-tosyl-2-(tosylamino)-substituted 1,4-benzoquinonimine regioselectively affords products of 1,4- and 6,3-addition with the latter prevailing. Arylsulfinate anion enters predominantly in the para-position with respect to the ArSO₂NH group.