Collect. Czech. Chem. Commun. 1997, 62, 1919-1930

Conformation of 5-Amino-5-deoxypentonolactams

Karel Kefurta, Jaroslav Havlíčekb, Michaela Hamerníkováa, Zdeňka Kefurtováa and Hana Votavovác

a Department of Chemistry of Natural Compounds, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
b Department of Analytical Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
c Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic


Four configuration isomers of 5-amino-5-deoxy-D-pentonolactam 1a-4a and their tri-O-acetyl derivatives 1b-4b were studied using NMR and CD spectroscopy. For all compounds chemical shifts of the 1H and 13C nuclei as well as of vicinal coupling constants were obtained. Comparison of the observed 3J(H,H) with those calculated for various conformations by a modified Karplus relationship led to the assignment of predominant conformation 3H4(D) or 4H3(D) to the lactams 1a-4a and 1b-4b in solution. The most important factor for determining the conformation seems to be the pseudoequatorial position of the substituent on the carbon next to the carbonyl group. The results of the CD spectra of the lactams 1a-4a in water, interpreted according to the currently used rules, agreed with the NMR results.

Keywords: Carbohydrates; Azasugars; Lactams; Conformation analysis; NMR spectroscopy; Circular dichroism.