CONFORMATIONAL-ANALYSIS OF SUBSTITUTED N-NITROSO-TRANS-DECAHYDROQUINOLIN-4-ONES

H-1 and C-13 NMR resonance assignments and conformational assignments were carried out for four N-nitroso-2-phenyl-trans-decahydroquinolin-4 -ones. In addition to conventional 1D NMR methods, 2D shift-correlated NMR techniques (H-1-H-1 COSY, H-1-H-1 NOESY and H-1-C-13 HETCOR) were used for the signal assignments. At room temperature the title compou nds exist in two isomeric forms, The preferred conformations of both t he isomers of nitrosamines were determined by a comparison of the spec tral data with those for the parent amines, and with the aid of substi tuent parameters, Molecular strain in nitrosamines is minimized by par tial escape of the piperidine moiety into non-chair conformation. (C) 1997 by John Wiley & Sons, Ltd.