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Characterization of novel isobenzofuranones by DFT calculations and 2D NMR analysis
Author(s) -
Teixeira Milena G.,
Alvarenga Elson S.
Publication year - 2016
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.4411
Subject(s) - chemistry , chemical shift , cyclopentadiene , computational chemistry , stereochemistry , furan , adduct , nmr spectra database , organic chemistry , spectral line , physics , astronomy , catalysis
Phthalides are frequently found in naturally occurring substances and exhibit a broad spectrum of biological activities. In the search for compounds with insecticidal activity, phthalides have been used as versatile building blocks for the syntheses of novel potential agrochemicals. In our work, the Diels–Alder reaction between furan‐2(5 H )‐one and cyclopentadiene was used successfully to obtain (3a R ,4 S ,7 R ,7a S )‐3a,4,7,7a‐tetrahydro‐4,7‐methanoisobenzofuran‐1(3 H )‐one and (3a S ,4 R ,7 S ,7a R )‐3a,4,7,7a‐tetrahydro‐4,7‐methanoisobenzofuran‐1(3 H )‐one ( 2 ) and (3a S ,4 S ,7 R ,7a R )‐3a,4,7,7a‐tetrahydro‐4,7‐methanoisobenzofuran‐1(3 H )‐one and (3a R ,4 R ,7 S ,7a S )‐3a,4,7,7a‐tetrahydro‐4,7‐methanoisobenzofuran‐1(3 H )‐one ( 3 ). The endo adduct ( 2 ) was brominated to afford (3a R ,4 R ,5 R ,7 R ,7a S ,8 R )‐5,8‐dibromohexahydro‐4,7‐methanoisobenzofuran‐1(3 H )‐one and (3a S ,4 S ,5 S ,7 S ,7a R ,8 S )‐5,8‐dibromohexahydro‐4,7‐methanoisobenzofuran‐1(3 H )‐one ( 4 ) and (3a S ,4 R ,5 R ,6 S ,7 S ,7a R )‐5,6‐dibromohexahydro‐4,7‐methanoisobenzofuran‐1(3 H )‐one and (3a R ,4 S ,5 S ,6 R ,7 R ,7a S )‐5,6‐dibromohexahydro‐4,7‐methanoisobenzofuran‐1(3 H )‐one ( 5 ). Following the initial analysis of the NMR spectra and the proposed two novel unforeseen products, we have decided to fully analyze the classical and non‐classical assay structures with the aid of computational calculations. Computation to predict the 13 C and 1 H chemical shifts for mean absolute error analyses have been carried out by gauge‐including atomic orbital method at M06‐2X/6‐31+G(d,p) and B3LYP/6‐311+G(2d,p) levels of theory for all viable conformers. Characterization of the novel unforeseen compounds ( 4 ) and ( 5 ) were not possible by employing only the experimental NMR data; however, a more conclusive structural identification was performed by comparing the experimental and theoretical 1 H and 13 C chemical shifts by mean absolute error and DP4 probability analyses. Copyright © 2016 John Wiley & Sons, Ltd.