Process for preparing a morphinan derivative

摘要

A process for preparing a morphinan derivative by providing a dihydrofuranyl bridged tetracycle halide of the formula (19) in which X is halogen, R is an alkyl group of from 1 to about 10 carbon atoms, and R1 is a protecting group. The pentacycle halide is converted into a morphinan derivative of formula (20) in which R is a previously defined.