63542-24-5Relevant articles and documents
Tautomeric preferences of phthalones and related compounds
Dobosz, Robert,Kolehmainen, Erkki,Valkonen, Arto,O?mia?owski, Borys,Gawinecki, Ryszard
, p. 9172 - 9178 (2008/03/11)
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.
β-Diceto enamines heterocycliques: 1. Indanediones-1,3 substituees en 2 par un heterocycle azote
Ploquin, J.,Sparfel, L.,Baut, G. Le,Floc'h, R.,Letourneux, Y.
, p. 961 - 973 (2007/10/02)
The condensation of methylated N-heterocycles and especially monomethyl- and polymethylpyridines on phthalic anhydrides leads to 2-aryl-1,3-indanediones.The 3-alkylidenylphthalides formed in an intermediary state have been isolated.The influence of solvents and temperature on the velocity and yield of formation of 2-(2- and 4-pyridyl)-1,3-indandiones has been studied.The ir and nmr spectra confirm that these compounds exist under a β-diketoenamine form resonating with a betaine form.
