Convenient conversions of codeine into 6‐demethoxythebaine via bond rearrangement (Chemistry of Opium Alkaloids, Part XVIII)

Two syntheses are described of (‐)‐6‐demethoxythebaine (4), both starting from the 6‐O‐mesyl**** derivative 2 of (‐)‐codeine. Treatment with sodium hydride in toluene gives (‐)‐6‐demethoxythebaine in 60% yield. The preparation via 8β‐bromo‐6,7‐didehydro‐4,5‐epoxy‐3‐methoxy‐17‐methylmorphinan (3), which is obtained from the mesyl derivative with the aid of lithium bromide, has an overall yield of 80%.