Patent ID: 7348430

Claim:
A process for the preparation of a 4,5-epoxymorphinan compound of formula (I) wherein R 1 is methyl, substituted methyl or alcohol protecting group; R 2 is hydrogen, methyl, substituted methyl or amine protecting group, R 3 is methyl, substituted methyl or alcohol protecting group; comprising the steps of (i) reacting an alcohol of formula (II) wherein R 1 and R 2 are as hereinbefore defined, with benzophenone and potassium tert-alkylate in hydrocarbon solvent to generate a reaction mixture containing the enolate of formula (III) wherein R 1 and R 2 are as hereinbefore defined; and (ii) adding reaction mixture containing the enolate of formula (III) to the electrophilic agent of formula (IV) R 3 X IV wherein R 3 is as hereinbefore defined and X is a leaving group, to yield a compound of formula (I), and (iii) isolating the compound of formula (I).