Oxidation of (-)-2-bromo-3-hydroxy-N-methyl-6-oxomorphinan with Fremy's salt. An unprecedented 2,4-shift of the bromo substituent. (Chemistry of opium alkaloids, Part XIII)
✍ Scribed by C. Olieman; L. Maat; H. C. Beyerman
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 831 KB
- Volume
- 99
- Category
- Article
- ISSN
- 0165-0513
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✦ Synopsis
Abstract
(‐)‐3‐Hydroxy‐N‐methyl‐6‐oxomorphinan (6a) and its (‐)‐2‐bromo derivative (6b) were converted into (‐)‐2,3‐dihydroxy‐N‐methyl‐6‐oxomorphinan (8a) and its (‐)‐4‐bromo derivative (8b), respectively, by oxidation with Fremy's salt to the ortho‐quinones, followed by reduction. Methylation of 8a and 8b gave the corresponding methyl ethers 9a and 9b. Catalytic hydrogenolysis of 8b and 9b gave 8a and 9a, respectively. The structure of (‐)‐2,3‐dimethoxy‐N‐methyl‐6‐oxomorphinan (9a) was confirmed by total synthesis, and that of (‐)‐4‐bromo‐2,3‐dimethoxy‐N‐methyl‐6‐oxomorphinan (9b) by single‐crystal X‐ray analysis.
The model compound 2‐bromo‐4,5‐dimethylphenol (15) gave, analogously, 3‐bromo‐4,5‐dimethyl‐pyrocatechol (16).