77896-52-7

Upstream product

• 77896-39-0 2-phenyl-2H-1,2,3-triazole 1-oxide 
• 77896-42-5 5-chloro-2-phenyl-1,2,3-triazole 1-oxide 
• 100-63-0 phenylhydrazine 
• 20672-18-8 2-(phenylhydrazono)ethanal 
• 77896-38-9 2-phenylhydrazonoglyoxal 1-oxime 
• 151-50-8 potassium cyanide 

Relevant academic research and scientific papers

INTRODUCTION OF SUBSTITUENTS INTO 5-MEMBERED AZA-HETEROAROMATICS

With emphasis on mono- and regio-selectively, methods for introduction of substituents at nitrogen and carbon atoms of 5-membered aza-heteroaromatics have been developed.The methods involve application of activation and of assistant groups for direction and protection.Activation has been achieved by the use of quaternary azolium ions and azol-N-oxides as reactive intermediates.If necessary, the N-oxides were further activated by alkylation or acylation.

1,2,3-Triazoles produced from 5-Substituted N-Methoxytriazolium Salts

Five reactions, two of which are new, have been observed when 5-substituted 1-methoxy-2-phenyltriazolium salts react with nucleophiles: (i) addition to C-4 with elimination of methanol to give unsymmetrically 4,5-disubstituted triazoles; (ii) displacement of the 5-substituent followed by secondary reactions to give a symmetrically 4,5-disubstituted triazole, a 5-substituted triazole N-oxide, a 4-substituted triazole, or a disubstituted benzeneazoacetonitrile; (iii) deprotonation of the N-methoxy-group with elimination of formaldehyde; (iv) demethylation; (v) abstraction of an α-proton from a 5-alkyl group followed by nucleophilic addition and elimination of methanol to give an α-substituted 5-alkyltriazole.The reactions are of synthetic potential as a means of introducing one or two substituents in the 1,2,3-triazole system.

Electrophilic and Nucleophilic Substitution in the Triazole N-Oxides and N-Methoxytriazolium Salts: Preparation of Substituted 1,2,3-Triazoles

2-Phenyltriazole 1-oxides are activated at C-5 towards both electrophilic and nucleophilic attack.The N-oxides can be selectively halogenated and, in turn, the halogen replaced by strong nucleophiles.On subsequent deoxygenation, the N-oxides yield halogeno-, methylthio-, and methoxy-triazoles.Methylation produces N-methoxytriazolium salts in which H-5 can be replaced by weak nucleophiles, e.g. fluoride ions.Thus fluoro-, chloro-, hydroxy-, alkoxy-, acyloxy-, amino-, substituted amino-, azido-, nitro-, mercapto-, alkylthio-, acylthio-, and cyano-substituents can be introduced in the triazole nucleus.Alternatively deprotonated N-methoxytriazolium salts react with electrophiles producing substituted triazole N-oxides.The reactions of triazole N-oxides with hydrogen chloride to give chlorotriazoles, and with acetyl chloride to give acetoxytriazoles, are explained.