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The regiospecific N ‐derivatization of histidine side chains: reinvestigation of a supposed N τ to N π migration
Author(s) -
Jones John H.,
Walker Victoria L.
Publication year - 1997
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/(sici)1099-1387(199709)3:5<391::aid-psc126>3.0.co;2-8
Subject(s) - chemistry , structural isomer , derivatization , side chain , ton , histidine , peptide , stereochemistry , substitution (logic) , medicinal chemistry , organic chemistry , high performance liquid chromatography , polymer , biochemistry , philosophy , fishery , biology , enzyme , linguistics
A report claiming that AcHisOMe reacts regiospecifically with 4‐fluoronitrobenzene to give AcHis[τPh(NO 2 )]OMe, which on treatment with H 2 /Pd(C) undergoes a partial τ–π shift to give some AcHis[πPh(NH 2 )]OMe, cannot be substantiated. 4(5)‐Methylimidazole, a model for AcHisOMe, gives on reaction with 4‐fluoronitrobenzene a 4:1 mixture of the regioisomers 1‐(4‐nitrophenyl),4‐methylimidazole, corresponding to τ‐substitution, and 1‐(4‐nitrophenyl),5‐methylimidazole, corresponding to π‐substitution, each of which has been isolated and fully characterized, including proof of orientation. In both cases, treatment with H 2 /Pd(C) gives a single product, without any change of orientation in either case. © 1997 European Peptide Society and John Wiley & Sons, Ltd. J. Pep. Sci. 3: 391–394 No. of Figures: 2. No. of Tables: 0. No. of References: 9