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ChemInform Abstract The title reaction between (I) and (II) yields the adducts (III) (X-ray analysis of the 4-O-phenyl ether: space group P212121; Z=4) and (IV). The latter is subsequently transformed to the desired morphinan derivative (VIII) (space group P212121; Z=4) which shows morphine-like activity in the PPQ assay.

~~ ~The 'H NMR and I3C NMR spectra of N-formylated morphinans were compared with those of the N-methyl and N-demethyl analogues. The magnitude of the changes in chemical shift of C-9, C-16 and C-10 depended crucially on the nature of the substituent at nitrogen. For the 6a,l4aethenoisomorphinans and 6~,14/?-ethenomorphinans, the proton chemical shifts of the 6,14-etheno bridge across ring C are differently affected by the nitrogen atom. In the 6a,14a-ethenoisomorphinans, the vinylic proton shifts are found between 65.3 and 5.9, whereas in the 68,148-ethenomorphinans these proton signals are found downfield from 66.0. A similar, but opposite, anisotropy effect of the nitrogen is observed for the 88-proton. These results are important for the elucidation of the structures of these types of compounds.

Abstract. Reaction of the anions of thebaine and 6-demethoxythebaine with 2-propanone gave the 5~-(dirnethylmethanoI)-substituted analogues 3 and 5 and the isomeric C-7-substituted morphinan-5,8-dienes 4, 6 and 7 , respectively. N o reaction took place with methanal. Therefore, thebaine-5P-methanol (10) was prepared by reacting the anion with alkyl chloroformate followed by lithium aluminium hydride reduction. Diels-Alder reaction of diene 10 with ethyl acrylate gave the 6a,l4a-ethenoisomorphinan 11. Of the morphinan-6,8-dienes 3 and 5, only diene 5 showed a reaction, namely rearrangement followed by cycloaddition with ethyl acrylate, yielding three adducts. T h e structure of the major adduct 13 was elucidated using 1D-and 2D-NMR techniques and revealed an aporphine-like structure. Furthermore, the conversion of 11 into a new etorphine analogue 16 was accomplished by treatment with methylmagnesium bromide followed by 3-0-dcmethylation.

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