Experimental and Theoretical Investigation of Epoxide Quebrachitol Derivatives Through Spectroscopic Analysis

Abstract

Two synthetic epoxide derivatives, important intermediates in organic synthesis, were obtained from L-quebrachitol, and their conformations were proposed based on spectroscopic analysis. Density functional theory (DFT) calculations of infrared and NMR spectra were shown to be reliable enough for organic chemistry applications. The observed structures were determined with the aid of the DFT spectroscopic data, stressing the relevance and utility of combined experimental/theoretical studies and also the usefulness of the (13)C NMR B3LYP/6-31G(d,p) calculations.

1H NMR analysis of O‐methyl‐inositol isomers: a joint experimental and theoretical study

“…B3LYP/6‐311 + G(2d,p) fully optimized structures for inositol isomers. The carbon numbering scheme was taken from De Almeida et al …”

Synthesis of Mercaptobenzothiazole and Mercaptobenzimidazole Condensed with Inositol Derivatives

“…l ‐Quebrachitol 5 (1‐ O ‐methyl‐ chiro ‐inositol), a natural optically active cyclic polyol isolated from Hevea brasiliensis latex, is a useful starting material for the synthesis of chiral compounds (see Scheme ) [16]. The chiral centers at C‐2 and C‐3 allows the stereo‐specific introduction of an heterocyclic moiety via epoxidation from the methanesulfonate of l ‐quebrachitol or benzoylated l ‐quebrachitol followed by regioselective opening of the epoxy ring by nucleophilic heterocycle [17,18].…”

Crystal Structure and 1H NMR Experimental and Theoretical Study of Conformers of 5-Methyl-1-(4’-methylphenylsulfonylamino)-1H-[1,2,3]-triazole-4-carboxylic Acid Ethyl Ester and 5-Methyl-1-(phenylsulfonylamino)-1H-[1,2,3]-triazole-4-carboxylic Acid Ethyl Ester

“…Finally, ωB97x-D/6-31G(d,p) harmonic frequency calculations were carried out to characterize the optimized structures as true minimum (all frequencies being real), allowing the calculation of thermodynamic properties, followed by calculations of 1 H magnetic shielding constants (σ), with chemical shifts (d), obtained on a d-scale relative to the TMS, taken as reference, using the gauge-independent atomic orbital (GIAO) method implemented by Wolinski et al 48 For the calculations of chemical shifts, the hybrid B3LYP functional was used, which has been shown to reproduce well the NMR spectra of organic molecules. [49][50][51][52] All calculations have been done with the Gaussian 09 package. 53…”