CIS-TRANS ISOMERISM AND CONFORMATIONAL STRUCTURE OF N-METHYLDODECANELACTAM AS STUDIED BY NMR, IR AND RAMAN-SPECTROSCOPY AND BY THEORETICAL CALCULATIONS
D. Doskocilova et al., CIS-TRANS ISOMERISM AND CONFORMATIONAL STRUCTURE OF N-METHYLDODECANELACTAM AS STUDIED BY NMR, IR AND RAMAN-SPECTROSCOPY AND BY THEORETICAL CALCULATIONS, Journal of molecular structure, 350(1), 1995, pp. 9-18
In H-1 and C-13 NMR spectra of N-methyldodecanelactam (I) in CDCl3 and
tetrachloroethane solution, the signals of various groups in cis and
trans forms of (I) were assigned by means of two-dimensional COSY, HET
COR (heteronuclear correlation spectroscopy) and ROESY methods. The co
nformational structure of the first two bonds neighbouring the amide b
ond was determined from J couplings in H-1 NMR spectra and theoretical
calculations (MM2, AM1). The barrier to rotation about the amide bond
was found from the temperature dependence of lineshapes in H-1 and C-
13 NMR spectra. IR and Raman spectra of(I) were measured in the temper
ature range 25 to - 140 degrees C and the intensity changes of vibrati
onal bands are discussed in connection with possible conformational tr
ansitions.