13C GIAO DFT calculation as a tool for configuration prediction of N-O group in saturated heterocyclic N-oxides

0378932 - ÚOCHB 2013 RIV GB eng J - Journal Article
Pohl, Radek - Potmischil, F. - Dračínský, Martin - Vaněk, Václav - Slavětínská, Lenka - Buděšínský, Miloš
13C GIAO DFT calculation as a tool for configuration prediction of N-O group in saturated heterocyclic N-oxides.
Magnetic Resonance in Chemistry. Roč. 50, č. 6 (2012), s. 415-423. ISSN 0749-1581. E-ISSN 1097-458X
R&D Projects: GA ČR GA203/09/1919
Institutional research plan: CEZ:AV0Z40550506
Keywords : NMR * 13C * 1H * saturated heterocyclic N-oxides * chemical shift calculations * DFT
Subject RIV: CC - Organic Chemistry
Impact factor: 1.528, year: 2012

Tropane, tropinone, pseudopelletierine and cocaine were oxidized in situ in a nuclear magnetic resonance (NMR) tube providing mixtures of exo/endo N-oxides. Observed 13C chemical shifts were correlated with values calculated by gauge-including atomic orbitals density functional theory (DFT) OPBE/6-31G method using DFT B3LYP/6-31G optimized geometries. The same method of 13C chemical shift calculation was applied on series of methyl-substituted 1-methylpiperidines and their epimeric N-oxides described in literature. The results show that using this undemanding calculation method enables assignment of configuration of NO group in N-epimeric saturated heterocyclic N-oxides. The approach enables assigning of the configuration with high degree of certainty even if NMR data of only one isomer are available. An improved method of in situ oxidation of starting amines in an NMR tube is also described.
Permanent Link: http://hdl.handle.net/11104/0210240