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.

Chirality

PubMedID: 23716294

Jakubowska A, Sowa A, Zylewski M, Kulig K. 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. Chirality. 2013;25(7):422-6.
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 (), their esters () with (R)- or (S)-2-methoxyphenylacetic acid () 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, d(RS) , for the relevant protons, it was also possible to confirm the absolute configurations at the C-2 centres of compounds and . Chirality, 25:422-426, 2013.© 2013 Wiley Periodicals, Inc.