Open AccessOn the Stability and Spectroscopic Properties of 5-Hydroxyoxazole-4-carboxylic Acid Derivatives
Author(s) -
Alina Tirla,
Kevin M. Wernke,
Seth B. Herzon
Publication year - 2021
Publication title -
organic letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.94
H-Index - 239
eISSN - 1523-7060
pISSN - 1523-7052
DOI - 10.1021/acs.orglett.1c01796
Subject(s) - chemistry , oxazole , decarboxylation , carboxylic acid , ring (chemistry) , hydrolysis , chemical shift , stereochemistry , organic chemistry , catalysis
5-Hydroxyoxazole-4-carboxylic acid residues were advanced as substructures within the secondary bacterial metabolites precolibactins 969 and 795a. However, oxazoles containing both 5-hydroxy and 4-carboxy substituents are unprecedented. We have found these oxazoles are unstable with respect to hydrolytic ring opening and decarboxylation. Comparison of reported and theoretical 13 C NMR chemical shifts between synthetic intermediates and the isolates revealed discrepancies in the oxazole region. These results suggest that precolibactins 969 and 795a may not contain 5-hydroxyoxazole-4-carboxylic acid residues.