N-Nitro-Substituted Azetidines and Aziridines. The Inherently Nonplanar Nitroamines: Conformational and Chiroptical Properties
作者:G. V. Shustov、A. Rauk
DOI:10.1021/jo00123a027
日期:1995.9
Optically active inherently nonplanar nitroamines, i.e., (2R)-1-nitro-2-methylazetidine (2b), (4S)-1-nitro-2,2-dibutyl-4-methylazetidine (2d), and (1R,SR,10R)-10-methyl-1,9-(N-nitroaziridino)decalin (3d), are synthesized and their CD, UV, and NMR spectra are studied. Experimental data are interpreted on the basis of nonempirical quantum chemical calculations of model compounds-the parent N-nitro-substituted azetidine 2a and aziridine 3a and their mono- and trimethyl derivatives 2a,b and 3b,c. It is shown that owing to the stereochemical lability of the pyramidal nitroamine chromophore, the closest asymmetrical environment causes torsional deformation of the chromophore and thus induces its intrinsic chirality. The latter determines the Cotton effect sign of the n(0)(-)-pi* transition in accordance with a spiral rule, which was formulated for the non-planar amide and nitrosoamine chromophores. The wavelength of the Cotton effect depends mainly on the pyramidality of the ring nitrogen atom and the intensity on the amount of twisting around the NN bond.