Synthesis, characterization and absolute configurations of methyl ladderanoates.

Autor: Harris CM; Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA., Harris TM; Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA., Stec DF; Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA., Schley ND; Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA., Johnson JL; Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA., Covington CL; Department of Chemistry, Austin Peay State University, Clarksville, Tennessee, USA., Polavarapu PL; Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA.
Jazyk: angličtina
Zdroj: Chirality [Chirality] 2023 Jan; Vol. 35 (1), pp. 49-57. Date of Electronic Publication: 2022 Nov 11.
DOI: 10.1002/chir.23515
Abstrakt: Methyl esters of [5]-ladderanoic acid and [3]-ladderanoic acid were prepared by esterification of the acids isolated from biomass at a wastewater treatment plant. Optical rotations at six different wavelengths (633, 589, 546, 436, 405 and 365 nm) and vibrational circular dichroism (VCD) spectra in the 1800-900 cm -1 region were measured in CDCl 3 solvent and compared with quantum chemical (QC) predictions using B3LYP functional and 6-311++G(2d,2p) basis set with polarizing continuum model representing the solvent. QC predictions gave negative optical rotations at all six wavelengths for (R)-methyl [5]-ladderanoate and positive optical rotations for (R)-methyl [3]-ladderanoate, the same signs as previously reported for the corresponding acids. The crystal structure of (-)-methyl [5]-ladderanoate independently confirmed (R) configuration. The QC-predicted VCD spectra using Boltzmann population weighted spectra of individual conformers did not provide satisfactory quantitative agreement with the experimental VCD spectra. An improved quantitative agreement for VCD spectra could be obtained when conformer populations were optimized to maximize the similarity between experimental and predicted VCD spectra, but more improvements in VCD predictions are needed.
(© 2022 Wiley Periodicals LLC.)
Databáze: MEDLINE
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