Synthesis and Study of Prototropic Tautomerism of 2-(2-Furyl)-1-hydroxyimidazoles

Novel 2-(2-furyl)imidazole derivatives were synthesised. 2-(2-Furyl)-1-methoxyimidazoles and 2-(2-furyl)-1-methylimidazole 3-oxides were used as model compounds in the study of the prototropic tautomerism of 2-(2-furyl)-1-hydroxyimidazoles by means of 1H, 13C NMR and UV/vis spectroscopies. It was demonstrated that the interaction of the π-excessive furyl moiety with an electron-withdrawing carbonyl group in position 5 of imidazole stabilised the N-hydroxy tautomeric form in both deuterated chloroform and d6-DMSO. In ethanol the N-oxide tautomer is also present along with the prevailing N-hydroxyimidazole.

Tautomer Database: A Comprehensive Resource for Tautomerism Analyses

<p>We report a database of tautomeric structures that contains 2,819 tautomeric tuples extracted from 171 publications. Each tautomeric entry has been annotated with experimental conditions reported in the respective publication, plus bibliographic details, structural identifiers (e.g. NCI CADD identifiers FICTS, FICuS, uuuuu, and Standard InChI), and chemical information (e.g. SMILES, molecular weight). The majority of tautomeric tuples found were pairs, the remaining 10% were triples, quadruples, or quintuples, amounting to a total number of structures of 5,977. The types of tautomerism were mainly prototropic tautomerism (79%), followed by ring-chain (13%) and valence tautomerism (8%). The experimental conditions reported in the publications included about 50 pure solvents and 9 solvent-mixtures with 26 unique spectroscopic or non-spectroscopic methods. ¹H and ¹³C NMR were the most frequently used methods. A total of 77 different tautomeric transform rules (SMIRKS) are covered by at least one example tuple in the database. This database is available as a spreadsheet for free download from <a href="https://cactus.nci.nih.gov/download/tautomer/">https://cactus.nci.nih.gov/download/tautomer/</a>.</p>

Tautomer Database: A Comprehensive Resource for Tautomerism Analyses

<p>We report a database of tautomeric structures that contains 2,819 tautomeric tuples extracted from 171 publications. Each tautomeric entry has been annotated with experimental conditions reported in the respective publication, plus bibliographic details, structural identifiers (e.g. NCI CADD identifiers FICTS, FICuS, uuuuu, and Standard InChI), and chemical information (e.g. SMILES, molecular weight). The majority of tautomeric tuples found were pairs, the remaining 10% were triples, quadruples, or quintuples, amounting to a total number of structures of 5,977. The types of tautomerism were mainly prototropic tautomerism (79%), followed by ring-chain (13%) and valence tautomerism (8%). The experimental conditions reported in the publications included about 50 pure solvents and 9 solvent-mixtures with 26 unique spectroscopic or non-spectroscopic methods. ¹H and ¹³C NMR were the most frequently used methods. A total of 77 different tautomeric transform rules (SMIRKS) are covered by at least one example tuple in the database. This database is available as a spreadsheet for free download from <a href="https://cactus.nci.nih.gov/download/tautomer/">https://cactus.nci.nih.gov/download/tautomer/</a>.</p>