Methyl 2-Methoxy Pyran-3 a Combined Experimental and Theoretical Investigation

Abstract

The title compound, methyl 2-methoxy-7-(4-methylbenzoyl)-4-oxo-6-p- tolyl-4H-furo[3,2-c]pyran-3-carboxylate (C<inf>25</inf>H<inf>20</inf>O<inf>7</inf>), was prepared and characterized by IR and single-crystal X-ray diffraction (XRD). The compound crystallizes in the triclinic space group P - 1 with a = 8.9554(9) Å, b = 10.0018(10) Å, c = 12.7454(13) Å, α = 67.678(7)°, β = 89.359(8)° and γ = 88.961(8)°. In addition to the molecular geometry from X-ray experiment, the molecular geometry and vibrational frequencies of the title compound in the ground state have been calculated using semiempirical AM1 and PM3 methods, as well as Hartree-Fock (HF) and density functional (B3LYP) levels of theory with 6-31G(d) basis set. To determine conformational flexibility, molecular energy profile of the title compound was obtained by semi-empirical (AM1) calculations with respect to two selected degrees of torsional freedom, which were varied from -180° to +180° in steps of 10°. Besides, frontier molecular orbitals (FMO) analysis and thermodynamic properties of the title compound were performed by the B3LYP/6-31G(d) method. © Springer-Verlag 2009.