A convergent synthesis of (17R,5Z,8Z,11Z,14Z)-17-hydroxyeicosa-5,8,11,14-tetraenoic acid analogues and their tritiated derivatives

17(R)-OH-AA and 14,15-dehydro-17(R)-OH-AA were synthesized from a common tetraacetylenic precursor and their azide derivatives were obtained in moderate yields via the corresponding p-toluenesulfonates. Since the azido group remained stable during tritiation procedure on Lindlar's catalyst in benzene, both 14,15-dehydro-17(S)-N₃-AA and 14,15-dehydro-17(R)-OH-AA constitute useful intermediates in the synthesis of radio-labelled 17(S)-N₃-AA and 17(R)-OH-AA. In contrast, reduction of azide in methanol afforded 17(S)-NH₂-AA with 95% yield.     

Thermophysics of alkali and related azides II. Heat capacities of potassium,rubidium, cesium,and thallium azides from 5 to 350 K

The heat capacities of potassium, rubidium, cesium, and thallium azides were determined from 5 to 350 K by adiabatic calorimetry. Although the alkali-metal azides studied in this work exhibited no thermal anomalies over the temperature range studied, thallium azide has a bifurcated anomaly with two maxima at (233.0±0.1) K and (242.04±0.02) K. The associated excess entropy was 0.90 cal_th K^?1 mol^?1. The thermal properties of the azides and the corresponding structurally similar hydrogen difluorides are nearly identical. Both have linear symmetrical anions. However, thallium azide shows a solid-solid phase transition not exhibited by thallium hydrogen difluoride. At 298.15 K the values of C_p^o, S^o, and $\text{?{G}{}^{\mathrm{o}}\text{(T)?H}{}^{\mathrm{o}}\text{(0)}}\text{T}$, respectively, are 18.38, 24.86, and 12.676 cal_th K^?1 mol^?1 for potassium azide; 19.09, 28.78, and 15.58 cal_th K^?1 mol^?1 for rubidium azide; 19.89, 32.11, and 18.17 cal_th K^?1 mol^?1 for cesium azide; and 19.26, 32.09, and 18.69 cal_th K^?1 mol^?1 for thallium azide. Heat capacities at constant volume for KN₃ were deduced from infrared and Raman data.     

Reaction of N-phenyl(benzylidene,phenoxy)acetyl-1,4-benzoquinone imines with sodium azide

N-Phenyl(benzylidene, phenoxy)acetyl-1,4-benzoquinone imines reacted with sodium azide to give the corresponding 1,4-addition products, N-(4-hydroxyphenyl) carboxamides. Quantum chemical calculations showed that the initial step in the examined reaction is addition of azide ion to neutral quinone imine molecule.     

Ladders,rings and cubes as structural motifs in three new zinc(II) azide complexes: Synthesis,spectral and structural characterization

Three new zinc(II) azide complexes, namely {[Zn₂(N₃)₄(py-tetrazole)₂](py-tetrazole)}_n (1), {[Zn₂(N₃)₄(3-OHpy)] · 2H₂O}_n (2) and [Zn(N₃)₂(pym)]_n (3), where py-tetrazole = tetrazolo[1,5-a]pyridine, 3-OHpy = 3-hydroxypyridine and pym = pyrimidine, have been synthesized by the hydrothermal methods and structurally characterized. The ligand py-tetrazole was obtained through the interaction of 2-chloropyridine with the azide ion under hydrothermal condition. The structure of 1 consists of a ladder-like arrangement of 1D double chain zinc(II) azide. In the coordination chain, each zinc atom binds di-EO azide bridges connecting another zinc atom in opposite chain, and two EO bridges, one on each side, and the fifth position is occupied by a N atom of py-tetrazole ligand. The structure of 2 features 2D sheets composed of tetranuclear zinc(II) ring and octanuclear zinc(II) ring interconnected by EO azide bridges. The 2D carrying into 3D supramolecular network by the help of several hydrogen bonding interactions. The 3-OHpy molecule acts in the tautomeric keto-form as O,O-bidentate bridging ligand. Complex 3 features distorted octahedral geometry around each zinc center, N,N′-bidentate pyrimidine ligand and EE azido bridges leading to 3D network structure. The IR spectra are measured and discussed. Complex 2 only exhibits photoluminescence properties whereas the other two complexes do not luminesce at room temperature.     

Unexpected 1,2,3-triazole formation in the reaction of diethylaluminum azide with α′-amino-α,β-unsaturated ketones

4-Acyl-1H-1,2,3-triazoles are formed from diethylaluminum azide and α′-(N,N-dibenzylamino)-α,β-unsaturated ketones by [3+2] cycloaddition of azide, followed by 1,5 hydride transfer to the β carbon of the triazoline side chain and fragmentation of the tertiary amino group promoted by coordination of the latter to the Lewis acid. The structure of a triazole product is confirmed by X-ray crystallography.     

A fast route for the synthesis of tetrazolyl oximes by a novel multicomponent reaction between Z-chlorooximes,isocyanides and trimethylsilyl azide

A library of twenty variously decorated 1,5-disubstituted-(1H-tetrazol-5-yl)methanone oximes was prepared in one single synthetic step exploiting the combination of (Z)-chlorooximes, isocyanides and trimethylsilyl azide. The formal [3+1] cycloaddition between isocyanides and nitrile N-oxides with respect to the [3+1] cycloaddition between isocyanides and azides prevails, while the direct attack of azide onto nitrile N-oxides remains competitive. Finally, an intramolecular cyclization of a (1H-tetrazol-5-yl)methanone oxime to a benzoisoxazole tetrazole is reported for the first time.     

Preparation and nucleophilic substitution of the N,N-1,2-naphthalenedisulfonylimide derivative of a chiral amine

In our series of nucleophilic substitution reactions on N,N-disulfonylimides we hereby report the preparation and the nucleophilic substitution of the N,N-1,2-naphthalenedisulfonylimide derivative 1a of the chiral amine 1. The disulfonimide was prepared by using the disulfonyl chloride reagent. Nucleophilic substitution of 1a by KNO₂ and azide afforded the corresponding alcohol 2 and the azide product 3 with, respectively, 63 and 70% inversion of configuration. The stereochemical results are compared with previously reported results for a series of N,N-disulfonylimides showing that the degree of inversion of 1a is lower than for the other N,N-disulfonylimides.     

The synthesis of 3,6-diamino-2,3,4,6-tetradeoxy-dl-threo-hexopyranose derivatives,substrates for the synthesis of negamycin

Three synthetic routes to derivatives of 3,6 - diamino - 2,3,4,6 - tetradeoxy - DL - threo - hexopyranose were investigated. Addition of sodium azide in acetic acid to 6 - phthalimido - 5,6 - dihydro - 2 - pyrone gave 4-azido compound (7) of the erythro configuration. From methyl 2,4 - dideoxy - β -dl- erythro - hexopyranoside threo 4 - phthalimido - 6 - phthalimidomethyl - tetrahydro - 2 - pyrone (17) was obtained in three steps in low overall yield. Addition of sodium azide in acetic acid to butyl 6 - oxo - 2 - hydroxy - hex - 4 - enoate followed by methylation, amonolysis of the ester group, and reduction gave methyl 3,6 - diacetamido - 2,3,4,6 - tetradeoxy - α - DL - threo - hexopyranoside (26).     

Practical enantioselective synthesis of (3S, 4R)-3-hydroxypiperidine-4-carboxylic acid

A practical enantioselective synthesis of (3S, 4R)-3-hydroxypiperidine-4-carboxylic acid was accomplished via an unconventional Evans anti-aldol reaction followed by a one-pot azide reduction/reductive cyclization.     

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.     

AgNO3 catalyzed synthesis of 5-substituted-1H-tetrazole via [3+2] cycloaddition of nitriles and sodium azide

An efficient one-pot, convenient catalysis for the synthesis of 5-substituted-1H-tetrazoles is reported. The [3+2] cycloaddition involves various nitriles, sodium azide in refluxing DMF and AgNO₃ as catalyst to give corresponding 5-substituted-1H-tetrazoles in good to excellent yields. It is expected that the reaction proceeds via in situ formation of a silver azide species, which participates in coordination of nitrile moiety followed by cycloaddition of azide ion to give tetrazole.     

N,N-1,2-Benzenedisulfonylimide,a new cyclic leaving group for the stereoselective nucleophilic substitution of amines

We hereby report the preparation and nucleophilic substitutions of the N,N-1,2-benzenedisulfonylimide derivatives 1a and 2a of the chiral amines 1 and 2. The nucleophilic attack of KNO₂ afforded the respective alcohols 3 and 4 with 84–90% inversion of configuration. Nucleophilic attack by the azide ion afforded the azide products 5 and 6 which were reduced to the corresponding inverted amines 1 and 2 (94–98.5% inversion). The improved leaving group ability of the N,N-1,2-benzenedisulfonylimides compared with previously reported N,N-disulfonylimides is discussed. Chiral GLC analysis of all products is summarized and the alternative chiral analysis of product 3 by ¹³C NMR using heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin as a chiral solvating agent (CSA) is discussed.     

(-)-Menthol as a source of new N,N-diamine ligands for asymmetric transfer hydrogenation

The synthesis of new chiral N-monotosylated-1,2-diamines based on the (-)-menthol skeleton is presented. The elimination of HCl from neomenthyl chloride obtained from an Appel reaction led to p-menth-3-ene in excellent yield. Further functionalization of the double bond in p-menth-3-ene with chloramine-T gave the corresponding N-tosylaziridines, which upon reaction with sodium azide and subsequent reduction of the azide functional group, formed the 1,2-diamine system. The synthesized chiral ligands proved effective in the asymmetric transfer hydrogenation of aromatic ketones and an endocyclic imine.     

Four component reaction of aldehydes,isocyanides, Me3SiN3, and aliphatic alcohols catalyzed by indium triflate

In the presence of catalytic amount of indium(III) Lewis acids, the four component reaction of aldehydes, isocyanides, trimethylsilyl azide and aliphatic alcohols smoothly proceeded to give alkoxylated 1H-tetrazole products in good yields. In particular, In(OTf)₃ and In(ONf)₃ showed notably high level of catalytic activity in this reaction.     

Catalyst-free Vicinal bromoazidation of olefins using TMSN3 and NBS

A rapid and efficient method has been developed for the synthesis of vicinal bromoazide directly from olefin using N-bromosuccinimide (NBS) and trimethylsilyl azide (TMSN₃) as the bromine and azide sources, respectively, without any catalyst in acetonitrile as solvent. The rate of reaction is remarkably fast in acetonitrile without catalyst to produce bromoazides in high yield.     

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.     

Metal triflate catalyzed highly regio- and stereoselective 1,2-bromoazidation of alkenes using NBS and TMSN3 as the bromine and azide sources

Metal triflate catalyzed 1,2-bromoazidation of alkenes was performed using N-bromosuccinimide (NBS) and trimethylsilyl azide (TMSN₃) as the bromine and azide sources, respectively. Among the metal triflates, Zn(OTf)₂ was found to be the best catalyst. This catalytic process represents a highly regioselective, stereoselective and high yielding method for the synthesis of anti-1,2-bromoazides from a variety of alkenes including α,β-unsaturated carbonyl compounds.     

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-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.     

Urea mediated 5-substituted-1H-tetrazole via [3 + 2] cycloaddition of nitriles and sodium azide

A simple, new and convenient metal free procedure for the synthesis of 5-substituted 1H-tetrazoles using various nitriles and sodium azide in the presence of urea and acetic acid with good to high yields is developed. The reaction plausibly proceeds through in situ formation of urea azide active complex without toxic and/or expensive metal catalysts.