Theoretical DFT study of the NMR parameters, shielding and spin-spin coupling constant, of the products of a pinacol alkenylboronates? Diels-Alder reaction.

M. M. VALLEJOS; S. C. PELLEGRINET; P. F. PROVASI; M. N. C. ZARYCZ

Montevideo

Congreso; 42nd International Congress of Theoretical Chemists of Latin Expression; 2016

Theoretical Chemists of Latin Expression

We have studied theoretically some magnetic properties for selected products of the Diels-Alder reactionsfor pinacol alkenylboronates with cyclopentadiene, which recently were synthesized and their structureswere determined by a combination of spectroscopic methods such as Infrared (IR), 1D and 2D NuclearMagnetic Resonance (NMR) and High Resolution Mass Spectrometry (HRMS). We calculated the NMRparameters, shielding (σ) and spin-spin coupling constant (J), for five reported boronate cycloadducts atB3LYP/cc-pVTZ-J level of theory, in order to help the elucidation of the NMR experimental spectra, i. e., toverify the assigned signals and to clarify the origin of ambiguous ones. We also seek to predict some signalsthat could not be experimentally determined and therefore gives further support to the NMR structurecharacterization of this kind of compound.We found that most of the experimental assignations are in good agreement with the calculations in thiswork. The computational data exhibit to be a good tool to clarify the nuclei which gives the signals that couldnot be precisely assigned. We also propose some possible σ?s and J?s values which could not be measuredexperimentally. Moreover we analyze carefully the shieldings and coupling constants within the bicyclo[2.2.1]heptane backbone and separately in the boron-substituent.