| Abstract: | The NMR spectra of a spiro oxirane ( 1 ) derivative of codeinone, codeine ( 2 ), isocodeine ( 3 ), 6-methylcodeine ( 4 ) and 6-methylisocodeine ( 5 ) were compared. NOE and double-resonance experiments were used to confirm the conformation of 1 , and the configuration about C-6 of 6-methylcodeine and 6-methylisocodeine. An interchange of the chemical shifts of the olefinic protons in 1 was noted, as compared with those in all of the other compounds. This interchange could be attributed to the bond anisotropies of the oxirane moiety. |
