3293
Novel Analgesics and Molecular Rearrangements in the Morphine-Thebaine Group. IV.' Acid-Catalyzed Rearrangements of Alcohols of the 6,14-endo-Ethenotetrahydrothebaine Series K. W. Bentley, D. G. Hardy, and B. Meek Contribution from the Research Laboratories, Reckitt and Sons Ltd., Kingston-upon-Hull, England. Receioed September 26,1966 Abstract: Alcohols of general structure I have been dehydrated to olefins I1 which have been further converted into 14-alkenylcodeinones V, themselves transformed by further acid-catalyzed reactions into recyclized products VI1 and IX and derivatives of 5,14-thebainone (XV). 14-(3-Methylbut-2-enyl)codeine (XXVII) has been converted into a derivative XXIX of (-)-sinornenilan, the structure of which has been demonstrated by spectral studies and by conversion via the bases XXX and XXXIII into the olefin XXXIV.
T
he alcohols of the 6,14-etheno- and -ethanotetrahydrothebaine and -0ripavine groups described in the preceding two papers in this series2 are all unstable in acid media, in which they suffer dehydration and rearrangement, the speed, extent, and course of which depends on the nature of the alcoholic group and the 6,14 bridge and on the conditions of the reaction. In all cases the first product appears to be an olefin. The olefins are generally preparable in good yield by heating the alcohols in 98-100% formic acid, though in some cases further reaction takes place before complete dehydration occurs. In no case was evidence obtained of the production of more than one olefin, and in the cases examined the olefin is the product of dehydration in the side chain rather than toward C-7. The olefin 11 (R1= R 2 = H) on ozonolysis affords formaldehyde and the ketone 111, and the olefin I1 (R' = H, R 2 = Et) yields propionaldehyde, thus confirming the structures assigned to these bases. The structure I1 (R1 = R 2 = H) for the olefin derived from the alcohol I (R = Me) is further confirmed by its production from the ketone I11 by the Wittig reaction, and by its nmr spectrum, which shows a two-proton signal at 6 4.80 (H2C=C
