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Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Conformational analysis of cis-3, 5-dioxa-bicyclo[5.4.0]undecane and its 4-substituted derivatives by DNMR, molecular
Wojciech Migda1, Anna Stankiewicz, Edward Szneler
1Department of Organic Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland.
Abstract:
Temperature-dependent (1)H and (13)C-NMR spectra of the title compounds are presented. Coalescence effects are discussed and assigned to dynamic process--the interconversion of bicyclic system. The free energies of activation covered the range 39-52 kJ/mol. The dioxepane ring adopts twist-chair (TC) conformation. GIAO/DFT calculation of isotropic shieldings for the set of low-energy conformations showed that only one conformer is present at 298 K in solution that matched well with experimental data.
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