Chiroptical properties of 2,2’‐bioxirane

Abstract

The two enantiomers of 2,2'-bioxirane were synthesized, and their chiroptical properties were thoroughly investigated in various solvents by polarimetry, vibrational circular dichroism (VCD), and Raman optical activity (ROA). Density functional theory (DFT) calculations at the B3LYP/aug-cc-pVTZ level revealed the presence of three conformers (G , G , and cis) with Gibbs populations of 51, 44, and 5% for the isolated molecule, respectively. The population ratios of the two main conformers were modified for solvents exhibiting higher dielectric constants (G form decreases whereas G form increases). The behavior of the specific optical rotation values with the different solvents was correctly reproduced by time-dependent DFT calculations using the polarizable continuum model (PCM), except for the benzene for which explicit solvent model should be necessary. Finally, VCD and ROA spectra were perfectly reproduced by the DFT/PCM calculations for the Boltzmann-averaged G and G conformers.

Enantioselective Complexation of Chiral Oxirane Derivatives by an Enantiopure Cryptophane in Water

“…23 °C). Buffeteau and co‐workers recently reported the chiroptical properties of the two enantiomers of 5 . On the other hand, the meso stereoisomer was purchased commercially.…”

“…Buffeteau and co-workers recently reported the chiroptical properties of the two enantiomers of 5. [13] On the other hand, the meso stereoisomer was purchased commercially. The high-field regions of the 1 H NMR spectra of the three diastereomers recorded at 278 K in NaOD/D 2 O solution are presented in Figure 3.…”

Nature of Interactions between Epoxides in Graphene Oxide

“…To have a clear understanding of other electronic factors affecting the nature of 1,3-interaction between epoxides, we explore the conformational space of the epoxide dimer. − With the cyclic constraints of the hexagonal rings removed, the epoxide groups can rotate around the central C–C bond to avoid steric repulsion between oxygen lone pairs, providing an opportunity to inquire about other factors affecting the conformational stability. Since the ipso carbon atoms of the epoxide dimer are equivalent stereogenic centers, we have three possible stereoisomers with RS (or equivalently SR ), RR , and SS enantiomers . Using DFT calculations, we probe (Chart ) the different conformations of the two diastereomers, which generate the various types of 1,3-interactions found in the C 2 O sheets.…”

“…Since the ipso carbon atoms of the epoxide dimer are equivalent stereogenic centers, we have three possible stereoisomers with RS (or equivalently SR), RR, and SS enantiomers. 38 Using DFT calculations, we probe (Chart 3) the different conformations of the two diastereomers, which generate the various types of 1,3-interactions found in the C 2 O sheets.…”