6533b827fe1ef96bd12864ac
RESEARCH PRODUCT
Tautomeric preferences of phthalones and related compounds
Ryszard GawineckiBorys OśmiałowskiErkki KolehmainenRobert DoboszArto Valkonensubject
ChloroformProtonOrganic ChemistryQuinolineInfrared spectroscopyAromaticityBiochemistryTautomerchemistry.chemical_compoundchemistryAb initio quantum chemistry methodsComputational chemistryDrug DiscoveryMoleculedescription
Abstract Multinuclear magnetic resonance and IR spectra prove that although 2-(diacylmethyl)pyridines and 2-(diacylmethyl)quinolines are β-diketones, their proton transfer product present in chloroform solution is not ketoenol but enaminone (earlier opinions were contradictory). Quinoline derivatives are less zwitterionic by character than the respective pyridyl congeners. The β-diketone form itself may also be rarely present in the solution. X-ray data show that 2-(2(1H)-pyridinylidene)-1H-indene-1,3(2H)-dione, i.e., enaminone tautomer of 2-(pyridin-2-yl)-2H-indene-1,3-dione, is also the only form present in crystal. Ab initio calculations show that the enaminone is usually more stable than other tautomeric forms. Values of geometry based aromaticity index HOMA (harmonic oscillator model of aromaticity) confirm that the zwitterionic structure really contributes to the enaminone forms detected.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2007-09-01 | Tetrahedron |