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Mechanism for the direct synthesis of tryptophan from indole and serine: a useful NMR technique for the detection of a reactive intermediate in the reaction mixture
Author(s) -
Yokoyama Yuusaku,
Nakakoshi Masamichi,
Okuno Hiroaki,
Sakamoto Yohko,
Sakurai Satoshi
Publication year - 2010
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2676
Subject(s) - chemistry , indole test , tryptophan , serine , mechanism (biology) , stereochemistry , computational chemistry , biochemistry , amino acid , phosphorylation , philosophy , epistemology
The reaction mechanism for the biomimetic synthesis of tryptophan from indole and serine in the presence of Ac 2 O in AcOH was investigated. Although the time‐course 1 H‐NMR spectra of the reaction of 5‐methoxyindole with N ‐acetylserine were measured in the presence of (CD 3 CO) 2 O in CD 3 CO 2 D, the reactive intermediate could not be detected. This reaction was conducted without 5‐methoxyindole in order to elucidate the reactive intermediate, but the intermediate could not be isolated from the reaction mixture. Since the intermediate would be expected to have a very short life time, and therefore be very difficult to detect by conventional analytical methods, the structure of the intermediate was elucidated using a 2D‐NMR technique, diffusion‐ordered spectroscopy (DOSY). Two intermediates were detected and confirmed to be 2‐methyl‐4‐methyleneoxazol‐5(4H)‐one and 2‐methyl‐4‐hydroxymethyloxazol‐5(4H)‐one. The present results demonstrated that DOSY is a powerful tool for the detection of unstable intermediates. Copyright © 2010 John Wiley & Sons, Ltd.