180723-17-5

Upstream product

• 70978-37-9 1-(azidomethyl)-4-methoxybenzene 
• 142-45-0 Acetylenedicarboxylic acid 

Downstream Products

• 31794-11-3 1-(p-methoxybenzyl)-1,2,3-triazole 
• 805315-84-8 1-(3-bromo-4-methoxybenzyl)-4-bromo-1,2,3-triazole 
• 180791-68-8 3-p-methoxybenzyl-1,2,3-triazole-1-oxide 

Relevant academic research and scientific papers

Azoles. Part 13. Synthesis and bromine → lithium exchange reactions of some 1-substituted 4,5-dibromo-1H-1,2,3-triazoles and 2-substituted 4,5-dibromo-2H-1,2,3-triazoles

4,5-Dibromo-1H-1,2,3-triazole was synthesised by various routes and reacted with chloromethyl methyl ether (N-1/2), methyl chloroformate (N-1), benzyl chloride (N-1), 4-methoxybenzyl chloride (N-1), 4-nitrobenzyl chloride (N-1/2) or triphenylmethyl chloride (N-2) under various conditions, to give isolable products substituted at the N-atoms shown in parentheses. 4,5-Dibromo-1-methoxymethyl-1H- and -2-methoxymethyl-2H-1,2,3-triazole reacted with butyllithium (in diethyl ether or tetrahydrofuran at low temperatures) at position-5 and the resulting lithiated derivatives were quenched with aqueous ammonium chloride, carbon dioxide, methyl chloroformate, benzophenone or dimethyl or diphenyl disulfide to give high yields (71-93%) of the corresponding 5-substituted 1,2,3-triazole. 1-Benzyl-4,5-dibromo-1H-1,2,3-triazole was converted similarly into 1-benzyl-4-bromo-5-methylsulfanyl-1H-1,2,3-triazole (91.5%). In a 'one pot' sequence and through two successive treatments with butyllithium and the appropriate quenching reagent (Ph2S2 and H2O), 4,5-dibromo-2-methoxymethyl-2H-1,2,3-triazole was converted similarly into 2-methoxymethyl-4-phenylsulfanyl-2.ff-1,2,3-triazole (47% yield).

Preparation of 1-hydroxypyrazoles and 1-hydroxy-1,2,3-triazoles by dealkylation of pyrazole and triazole N-oxides

1-Hydroxypyrazoles were obtained from 2-benzylpyrazole 1-oxides by debenzylation with iodotrimethylsilane. 1-Hydroxy-1,2,3-triazoles were achieved from 2-benzyltriazole 1-oxides by debenzylation effected with conc. hydrobromic acid or from 2- or 3-p-methoxybenzyltriazole 1-oxides by de-p methoxybenzylation accomplished by treatment with conc. sulfuric acid. 1-Methoxy-1,2,3-triazole was obtained by de-p-methoxybenzylation of 1-methoxy-3-p-methoxybenzyl-1,2,3-triazolium tetrafluoroborate accomplished by treatment with conc. sulfuric acid. 1-Hydroxypyrazole was selectively N-benzylated in absence of base to give 2-benzylpyrazole 1-oxide which, upon selective substitution at the 3-position and subsequent debenzylation, produced 3-substituted 1-hydroxypyrazole. Acta Chemika Scandinavica 1996.

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.