title: Application of NMR spectroscopy for assignment of the absolute configuration of 8-tert-butyl-2-hydroxy-7-methoxy-8-methyl-9-oxa-6-azaspiro[4.5]dec-6-en-10-one.
abstract: In order to assign the absolute configurations of 8-tert-butyl-2-hydroxy-7-methoxy-8-methyl-9-oxa-6-azaspiro[4.5]dec-6-en-10-one (2a,b), their esters (5a-d) with (R)- or (S)-2-methoxyphenylacetic acid (4a,b) have been synthesized. The absolute configurations of these compounds have been determined on the basis of NOESY correlations between the protons of the tert-butyl group and the cyclopentane fragment of the molecules. The crucial part of this analysis was assignment of the absolute configuration at C-5. Additionally, by calculation of the chemical shift anisotropy, δ(RS), for the relevant protons, it was also possible to confirm the absolute configurations at the C-2 centres of compounds 2a,b and 5a-d.
authors.affiliation: Department of Physicochemical Drug Analysis, Chair of Pharmaceutical Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, Kraków, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Jakubowska
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Sowa
authors.forename: Marek
authors.initials: M
authors.lastname: Zylewski
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kulig
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D001372:Aza Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013141:Spiro Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: C586657:8-tert-butyl-2-hydroxy-7-methoxy-8-methyl-9-oxa-6-azaspiro(4.5)dec-6-en-10-one; D001372:Aza Compounds; D013141:Spiro Compounds; D019342:Acetic Acid
keywords: 6-azaspiro[4.5]dec-6-en-10-one; NMR spectroscopy; NOESY; absolute configuration; chiral derivatization agent