SYNTHESIS OF ENANTIOMERICALLY PURE MORPHINE ALKALOIDS - THE HYDROPHENANTHRENE ROUTE

A concise, linear, total synthesis of (-)-dihydrocodeinone-a close syn thetic precursor of(-)-codeine and (-)-morphine-has been achieved. The carbocyclic core of the alkaloid was provided in the form of a phenan threnone, which was resolved by chromatography on cellulose triacetate . A cuprate conjugate addition was used to establish the crucial benzy lic quaternary stereocenter and to introduce the Ct-side chain. Dimeri c byproducts provide evidence for a single electron transfer (SET) mec hanism. Unusual S(N)2 and radical cyclizations were employed for the f ormation of the dihydrobenzofuran and the piperidine ring, respectivel y.