Proton-Transfer Reactions between 7-Hydroxycoumarin and Tertiary Amines. Formation of the Ground-State Tautomer Anion

摘要

The UV absorption, fluorescence, and ~(13)C NMR studies of proton-transfer reactions between the title compound (7-HC) and tertiary amines confirmed that the hydrogen-bonded 7-HC tautomer anion, being stable in the ground state at room temperature, is exclusively produced in acetonitrile containing l,8-diazabicyclo[5.4.0]undec-7-ene. In addition, 7-HC in the ground state was found to give the hydrogen-bonded complex and 7-HC anion in the presence of the less basic amines, pyridine and triethylamine, respectively, but not to afford the 7-HC tautomer anion formation of which is markedly enhanced in the excited singlet state.