Simple conversion of aromatic amines into azides

[reaction: see text] A straightforward and highly efficient synthesis of aromatic azides from the corresponding amines is accomplished using triflyl azide under mild conditions.     

Reduction of azides to amines mediated by tin bis(1,2-benzenedithiolate)

[reaction: see text] A procedure for the conversion of azides to amines, which uses NaBH4 and catalytic amounts of tin(IV) 1,2-benzenedithiolate, is disclosed. Primary, secondary, tertiary, aromatic, and heteroaromatic azides are reduced in excellent yields under very mild conditions.     

Metal-free carbon-nitrogen bond-forming coupling reaction between arylboronic acids and organic azides

A novel and efficient metal-free carbon-nitrogen bond-forming coupling reaction between arylboronic acids and organic azides is reported. The reaction is fairly general for the preparation of secondary aromatic amines. Furthermore, the reaction is very functional-group tolerant. A possible mechanism is also proposed.     

Heteroacyl azides as acylating agents for aromatic or heteroaromatic amines

The possibility of formation of substituted heterocyclic amides from heteroacyl azides and aromatic or heteroaromatic amines was investigated. Although acylation proceeded in some cases under mild reaction conditions, formation of N,N′-disubstituted ureas was the main process at elevated temperatures.     

Chemoselective Aromatic Azido Reduction with Concomitant Aliphatic Azide Employing Al/Gd Triflates/NaI and ESI‐MS Mechanistic Studies

Aluminium and gadolinium triflates catalyze the chemoselective reduction of aromatic azides to the corresponding amines in combination with sodium iodide. This mild chemoselective method has been applied to the synthesis of various aryl amines, C2‐azido‐substituted pyrrolo[2,1‐c][1,4]benzodiazepines, and fused[2,1‐b]quinazolinones by an intramolecular azido reduction tandem cyclization reaction. Interestingly, this methodology selectively reduces aryl azides with enhanced yields and proceeds in shorter reaction times than previous strategies. The mechanistic aspects have been investigated and the intermediates associated with this selective transformation have been intercepted and characterized by online monitoring of the reaction by ESI‐MS.     

Three-component synthesis of N-sulfonylformamidines in the presence of magnetic cellulose supported N-heterocyclic carbene-copper complex,as an efficient heterogeneous nanocatalyst

A cellulose based magnetic nanocomposite possessing NHC-Cu Complex has been synthesized and characterized. It was then applied as a highly active catalyst in one-pot three-component reaction of sulfonyl azides, secondary amines and triethylamine to afford N-sulfonylformamidines. Copper catalyzed oxidative transformation of C-N bond of triethylamine is a key step to give desired products. In contrast with the good reactivity of the conventional secondary amines, aromatic amines and NH containing heteroaromatics had no activity in these reactions. Moreover, the used nanocatalyst which could be recovered by external magnet, showed reasonable catalytic activity for several times.     

A one-pot azido reductive tandem mono-N-alkylation employing dialkylboron triflates: online ESI-MS mechanistic investigation

An efficient one-pot reductive tandem mono-N-alkylation of both aromatic and aliphatic azides using dialkylboron triflates as alkylating agents has been examined under standardized reaction conditions. This methodology after optimization has been employed toward the syntheses of various secondary alkyl as well as aryl amines, including the synthesis of N10-butylated pyrrolo[2,1-c][1,4]benzodiazepine-5,11-diones via in situ azido reductive-cyclization process. This protocol is particularly attractive to provide an environmentally benign and practical method for mono-N-alkylation from organic azides without the use of toxic catalysts or corrosive alkylating agents. In addition, the mechanistic aspects have been investigated and the intermediates associated with this selective transformation have been intercepted and characterized by online monitoring of the reaction by ESI-MS/MS.     

Conversion of tertiary alcohols to tert-alkyl azides by way of quinone-mediated oxidation-reduction condensation using alkyl diphenylphosphinites

A novel method for the preparation of alkyl azides from alcohols by way of oxidation-reduction condensation is described. In this reaction, the sterically-hindered tert-alkyl phosphinites that are prepared from the corresponding alcohols are converted into tert-alkyl azides with almost complete inversion of their stereochemistry: the obtained alkyl azides are then successfully reduced to afford the corresponding amines on treatment with LiAlH₄, thus, a versatile method for the preparation of chiral amines from the corresponding chiral alcohols is established.     

Reduction of Azides to Amines with New Metal／Lewis Acid Systems in H2O or Aqueous EtOH

The azides were reduced to the corresponding amines by two new meml/LEwis acid systems in water or in aqueous EtOH in yields ranging from 80%-95%. The reaction rates were faster in water than in aqueous EtOH in most cases. All 16 azides with different functional groups were well reduced to the corresponding amines in excellent yields and reaction rates.     

Synthesis of hydrazide,azide and substututed amides of carboxymethylchitin

Synthesis of hydrazide, azide and substututed amides of carboxymethylchitin is reported. Stability of azides in aqueous solution and their acylating ability in the reactions with aromatic amines are studied.     

Reduction of Azides to Amines with Borohydride Exchange Resin – Nickel Acetate

Borohydride exchange resin (BER) - nickel acetate system in methanol readily reduces both aliphatic and aromatic azides to the corresponding amines in excellent yields.     

Organoboranes for synthesis : Reaction of organoboranes with representative organic azides. A general stereospecific synthesis of secondary amines and N-substituted aziridines

Reaction of trialkylboranes with organic azides in refluxing xylene, followed by hydrolysis, leads to good yields of secondary amines. This reaction is highly dependent on the steric effects around both boron and the azide moiety. The reaction becomes much slower when the steric bulk of one of the reagents is increased and fails when both are hindered. The dialkylchloroboranes are more reactive than trialkylboranes and provide better yields of the desired secondary amines with a11 azides tested. The alkyldichloroboranes react with organic azides at temperatures between room temperature and 60°C and produce excellent yields of secondary amines. Furthermore, the stereochemistry of the original carbon-boron bond is retained. The mechanism of these reactions is discussed and the reaction applied to the synthesis of N-alkyl- and N-arylaziridines.     

Synthesis of 6-amino-5-cyano-1,4-disubstituted-2(1H)-pyrimidinones via copper-(I)-catalyzed alkyne-azide 'click chemistry' and their reactivity

In this paper we present the room temperature synthesis of a novel serie of 1,4-disubstituted-1,2,3-triazoles 4a-l by employing the (3+2) cycloaddition reaction of pyrimidinones containing alkyne functions with different model azides in the presence of copper sulphate and sodium ascorbate. To obtain the final triazoles, we also synthesized the major precursors 6-amino-5-cyano-1,4-disubstituted-2(1H)-pyrimidinones 3a-r from ethyl 2,2-dicyanovinylcarbamate derivatives 2a-c and various primary aromatic amines containing an alkyne group. The triazoles were prepared in good to very good yields.     

Pd/C催化下汉斯酯1,4-二氢吡啶还原芳香叠氮化合物、芳香硝基 化合物以及碳碳双键的反应研究

汉斯酯1,4-二氢吡啶(HEH)在Pd/C催化下可以将取代的芳香叠氮化合物还原为相应的取代苯胺, 反应具有很好的选择性. 该方法也可以用于芳香硝基化合物的还原. 对于Pd/C催化下汉斯酯1,4-二氢吡啶还原碳碳双键的可行性, 论文中也进行了初步的探讨.     

Direct electrochemical imidation of aliphatic amines via anodic oxidation

Direct electrochemical synthesis of sulfonyl amidines from aliphatic amines and sulfonyl azides was realized with good to excellent yields. Traditional tertiary amine substrates were broadened to secondary and primary amines. The reaction intermediates were observed and a reaction mechanism was proposed and discussed.     

Radical azidonation of aldehydes

Aliphatic and aromatic aldehydes can be converted to acyl azides by treatment with iodine azide at 0-25 degrees C. If the reaction is performed at reflux Curtius rearrangement occurs and carbamoyl azides are obtained in 70-97% yield from the aldehyde. The reaction was shown to have a radical mechanism.     

Syntheses and spectral properties of functionalized, water-soluble BODIPY derivatives

The objective of this work was to form water-soluble 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivatives. Sulfonation conditions were developed for several BODIPY dyes to give the monosulfonated products 1a-3a and the disulfonated products 1b-3b. Compounds 1 are functionalized with an aryl iodide for organometallic couplings. Similarly, 2 has an aromatic bromide but also two chlorine atoms that could be replaced via SNAr reactions. The amine 3 is amenable to couple to biomolecules via acylation reactions. A diazotization/azide reaction sequence was used to convert the amines 3 into azides 4; the latter may be functionalized via click reactions as illustrated by conversion of 4b into 5. Compound 5 was designed to have an acid-functional group to facilitate activation and coupling to amines. Spectral data for these materials indicate they are highly fluorescent probes in aqueous environments.     

Direct catalytic azidation of allylic alcohols

A direct catalytic azidation of primary, secondary, and tertiary allylic alcohols has been developed. This new azidation reaction affords the corresponding allylic azides in high to excellent yields and regioselectivities. The reaction provides straightforward access to allylic azides that are valuable intermediates in organic synthesis, including the preparation of primary amines or 1,2,3-triazole derivatives.     

Efficient amidation from carboxylic acids and azides via selenocarboxylates: application to the coupling of amino acids and peptides with azides

A facile one-pot procedure for the coupling of carboxylic acid and azide via selenocarboxylate and selenatriazoline has been developed and successfully applied to the coupling of amino acids and peptides with azides. Selenocarboxylates are readily prepared by the reaction of the activated carboxylic acids with LiAlHSeH under mild conditions. The selenocarboxylates formed in situ are used to react directly with azides to form the corresponding amides via a selenatriazoline intermediate. Excellent yields were obtained for electron-deficient azides, and moderate to good yields were obtained for electron-rich azides. The selenocarboxylate/azide amidation reaction is clean and chemoselective. It provides an attractive alternative method to the conventional acylation of amines when an amide bond needs to be formed without going through an amine intermediate.     

From azides to nitriles. A novel fast transformation made possible by BrF3

[reaction: see text]. Various alkyl and aryl azides, readily obtained from halides or alcohols, were transformed into the corresponding nitriles using bromine trifluoride in moderate to good yields. The reaction is general and gives positive results with aliphatic, aromatic, cyclic, and functionalized azides. It can also be applied to the synthesis of optically active nitriles.