Abstract
A facile and unprecedented synthesis of 2,3-diiodinated or 2,6-diiodinated diaryl
ether/thioether derivatives through regioselective Ullmann-type cross couplings of
5-substituted 1,2,3-triiodobenzenes and phenols/thiophenols is described. Remarkably,
the coupling reactions are simply controlled by the type of nucleophiles and the nature
of C5 substituent at 1,2,3-triiodoarenes providing the internal or terminal coupling products
in high regioselectivity and good isolated yields. Noticeable steric and electronic
effects were clearly observed on both 1,2,3-triiodoarenes and nucleophiles. The highest
yields were isolated from a combination between either electron-poor 1,2,3-triiodoarenes
and phenols or electron-rich 1,2,3-triiodoarenes and thiophenols. The optimized conditions
were found to be suitable for several functional groups. Using this methodology, mammary
carcinoma inhibitor BTO-956 is prepared in only one step with excellent regioselectivity
and good isolated yield. This report discloses the first method to prepare 2,3-diiodinated
and 2,6-diiodinated diaryl ethers/thioethers in one step that is efficient, regioselective,
and general in scope. The products are truly remarkable precursors for other transformations.
Key words
ortho -diiododiaryl ethers/thioethers - BTO-956 - Ullmann-type coupling - substituent effect
- catalyst
