Collect. Czech. Chem. Commun. 1982, 47, 17-28

Non-planar conformations of methylacetamide: Solvent effect and chiroptical properties

Igor Tvaroškaa, Slavomír Bystrickýa, Petr Maloňb and Karel Bláhab

a Institute of Chemistry, Slovak Academy of Sciences, 809 33 Bratislava
b Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


Molecular geometries of the cisoid and transoid forms of N-methylacetamide were optimized by semiempirical methods PCILO, MNDO and MINDO/3. The first two methods afford conformations with the non-planar amide group characterized by a slightly twisted pyramid of bonds on the nitrogen atom. The positions of energy minima are distinctly shifted if the effect of solvent simulated by a continuum model is considered. Optical rotatory strengths computed for non-planar conformations exhibit quantitative agreement with previous calculations and with actual CD spectra of rigid model lactams as well.