| Abstract
| - Benzopyranoimidazolones could virtually exist in four tautomeric forms, namely N3−H, N1−H, coumarinO−H, and C2−H. Experimental evidence reported thus far has been unable to lead to a unique statementabout the preferred tautomeric forms in solution. In this work, tautomeric equilibria for a series of2-substituted [1]benzopyrano[3,4-d]imidazol-4(3H)-ones were investigated by DFT calculations, in bothgas phase and solution. The influence of the solvent was included in the calculations by the CPCMsolvent model. 13C chemical shifts of all tautomers were computed at different levels of theory and thencompared with experiments to assign the preferred tautomers. Theoretical findings were then comparedto dynamic 1H NMR experiments results.
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