A Crystalline Dimeric Steroidal Diboronate with Electronically Impeded Rotation

0566053 - ÚFCH JH 2024 RIV US eng J - Journal Article
Vazquez-Chavez, J. - Martínez-Torres, F. C. - Navarro-Huerta, A. - Flores-Álamo, M. - Maldonado-Domínguez, Mauricio - Blahut, Jan - Štoček, Jakub Radek - Dračínský, Martin - Rodríguez-Molina, B. - Iglesias-Arteaga, M. A.
A Crystalline Dimeric Steroidal Diboronate with Electronically Impeded Rotation.
Journal of Organic Chemistry. Roč. 88, č. 1 (2023), s. 49-59. ISSN 0022-3263. E-ISSN 1520-6904
R&D Projects: GA ČR(CZ) GA20-01472S
Research Infrastructure: e-INFRA CZ - 90140
Institutional support: RVO:61388955 ; RVO:61388963
Keywords : dimeric steroid SMR-3 * NMR data * molecular dynamics
OECD category: Physical chemistry
Impact factor: 3.6, year: 2022
Method of publishing: Limited access

The dimeric steroid SMR-3, featuring a 1,4-phenyldiboronic ester flanked by two pregnan-triol frameworks, was synthesized to explore the intramolecular dynamics of its central component. The structural data from single-crystal X-ray diffraction studies and the Hirshfeld analyses indicate small steric effects around the aromatic ring that should favor the intended motion. However, solid-state NMR data obtained through VT 13C{1H} CPMAS and 2H spin-echo experiments, using the deuterated analogue SMR-3D4, revealed that this component is rigid even at temperatures where other reported steroidal molecular rotors experience fast rotation (85 °C). A combination of classical molecular dynamics, molecular mechanics, and correlated ab initio calculations allowed us to distinguish the steric and electronic factors that restrict the potential motion in this compound. The experimental and computational data reveal that electronic components dominate the behavior and are responsible for the high rotational barrier in the SMR-3 crystal.
Permanent Link: https://hdl.handle.net/11104/0337490