| Autor: |
Bell, Natalie V., Bowman, W. Russell, Coe, Paul F., Turner, Andrew T., Whybrow, Del |
| Zdroj: |
Canadian Journal of Chemistry; June 1997, Vol. 75 Issue: 6 p873-883, 11p |
| Abstrakt: |
The biomimetic oxidative coupling of the ethyl ester of N-acetyl-3,5-diiodotyrosine (1) to yield the ethyl ester of N-acetylthyroxine (2) has been investigated. A putative mechanism involving phenolic coupling to yield an intermediate aryloxydienone (7) followed by an E2 elimination for loss of the side chain has been proposed. Oxidative couplings with analogous 4-substituted 3,5-diiodophenols indicate that a number of mechanisms are possible; these include quinone methide intermediates and SN2 substitutions in the intermediate aryloxydienones. Rearomatization of the intermediate aryloxydienones is a strong driving force for the loss of the side chains. The results indicate that 3,5-diiodo-4-aryloxydienones are good leaving groups in E2 and SN2 mechanisms. The synthetic method provides a facile synthesis of thyroxine analogues from readily available 4-substituted 3,5-diiodophenols. Keywords: diiodotyrosine, phenolic coupling, phenoxyl radicals, thyroxine. |
| Databáze: |
Supplemental Index |
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