Producción Científica Profesorado

DFT and NMR parameterized conformation of valeranone



Meléndez Rodríguez, Myriam

2004

J. Martín Torres-Valencia, Myriam Meléndez-Rodríguez, Rocío Alvarez-García, Carlos M. Cerda-García-Rojas, Pedro Joseph-Nathan DFT and NMR parameterized coformation of valeranone Magnetic Resonance in Chemistry, volume 42, Issue 10, October 2004, Pages: 898-902, article first published online: 16 Aug 2004, DOI: 10.1002/mrc.1440


Abstract


A Monte Carlo random search using molecular mechanics, followed by geometry optimization of each minimum energy structure employing density functional theory (DFT) calculations at the B3LYP/631G* level and a Boltzmann analysis of the total energies, generated accurate molecular models which describe the conformational behavior of the antispasmodic bicyclic sesquiterpene valeranone (1). The theoretical HCCH dihedral angles gave the corresponding 1H, 1H vicinal coupling constants using a generalized Karplus-type equation. In turn, the 3J(H,H) values were used as initial input data for the spectral simulation of 1, which after iteration provided an excellent correlation with the experimental 1H NMR spectrum. The calculated 3J(H,H) values closely predicted the experimental values, excepting the coupling constant between the axial hydrogen ? to the carbonyl group and the equatorial hydrogen ? to the carbonyl group (J2?, 3?). The difference is explained in terms of the electron density distribution found in the highest occupied molecular orbital (HOMO) of 1. The simulated spectrum, together with 2D NMR experiments, allowed the total assignment of the 1H and 13C NMR spectra of 1. Copyright 2004 John Wiley & Sons, Ltd.



Producto de Investigación




Artículos relacionados

Conformationalstudies of N-carbomethoxy-2-alkoxyindolenines by dynamicNMR, crystallography, and mole...

First Total Synthesis of ()-Flustraminol B

Synthesis of Indolylindolines Mediated by tert-BuNH2

Mechanisticstudies of the photochemicalrearrangement of 1-oxolongipin-2-ene derivatives

Photochemical rearrangements of highly functionalized longipinene derivatives

Absolute configuration determination of 2-(2-oxo-3-indolyl)acetamide derivatives

Cleavage of alkoxycarbonylprotectinggroups from carbamates by t-BuNH2

DFT and NMR parameterized conformation of valeranone

Transesterifications mediated by t-BuNH2

Synthesis of Bromoindole Alkaloids from Laurencia brongniartii