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From N ‐(dinitrophenyl) amino acids to benzimidazole N ‐oxides. Synthesis, kinetics and mechanism
Author(s) -
Buján Elba I.,
Salum María Laura
Publication year - 2006
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1017
Subject(s) - chemistry , dinitrophenyl , benzimidazole , reaction rate constant , kinetics , glycine , medicinal chemistry , oxide , derivative (finance) , stereochemistry , amino acid , organic chemistry , biochemistry , physics , quantum mechanics , economics , antibody , financial economics , immunology , biology
Several benzimidazole N ‐oxide derivatives were synthesized in very good yields by heating under reflux the corresponding N ‐(2,4‐ or 2,6‐dinitrophenyl) amino acid derivative with NaOH in 60% 1,4‐dioxane–H 2 O. The N ‐oxides obtained from glycine and α‐ and β‐alanine derivatives lost the carboxylic group. The observed rate constant for the reaction of N ‐(2,4‐dinitrophenyl) glycine ( 2a ) in 10% 1,4‐dioxane–H 2 O to give 5‐nitro‐1 H ‐benzimidazole‐3‐oxide ( 4a ) is first order on [NaOH]; the second‐order rate constant is k N =1.7×10 −3 M −1 s −1 . The mechanism proposed includes the formation of an N ‐alkylidene 2‐nitrosoaniline‐type intermediate as the rate‐determining step. Copyright © 2006 John Wiley & Sons, Ltd.