Methyl 2-methoxy-7-(4-methylbenzoyl)-4-oxo-6-p-tolyl-4H-furo[3,2-c]pyran-3-carboxylate:A combined experimental and theoretical investigation.

The title compound, methyl 2-methoxy-7-(4-methylbenzoyl)-4-oxo-6-p-tolyl-4H-furo[3,2-c]pyran-3-carboxylate (C(25)H(20)O(7)), 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) A, b = 10.0018(10) A, c = 12.7454(13) A, alpha = 67.678(7) degrees , beta = 89.359(8) degrees and gamma = 88.961(8) degrees . 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 degrees to +180 degrees in steps of 10 degrees . Besides, frontier molecular orbitals (FMO) analysis and thermodynamic properties of the title compound were performed by the B3LYP/6-31G(d) method.