- Ortho-selectivity in the nucleophilic aromatic substitution (S NAr) reactions of 3-substituted, 2,6-dichloropyridines with alkali metal alkoxides
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3-Substituted, 2,6-dichloropyridines have featured in the syntheses of small molecule inhibitors of a wide variety of biological targets. Hence, the regioselective displacement of the chlorines is of significant interest. Through conducting an extensive solvent study, we have found that non-polar, aprotic solvents of low hydrogen bond basicities favour substitution of the chlorine ortho to the 3-substituent by alkali metal alkoxides. We present convincing evidence that coordination of the alkali metal counter-ion to the 3-substituent (nitro, ester, amide) is the origin of the ortho-selectivity to give a cyclic, six-membered transition state. Excellent ortho-selectivities (≥98:2) for secondary and tertiary alkoxides were realized with the sodium counter-ion, whereas the more reactive primary alkoxides required the harder, more Lewis acidic lithium counter-ion.
- Yap, Jeremy L.,Hom, Kellie,Fletcher, Steven
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scheme or table
p. 4172 - 4176
(2011/09/19)
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- Cell adhesion inhibitors
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The present invention relates to novel compounds that are useful for inhibition and prevention of cell adhesion and cell adhesion-mediated pathologies. This invention also relates to pharmaceutical formulations comprising these compounds and methods of using them for inhibition and prevention of cell adhesion and cell adhesion-mediated pathologies. The compounds and pharmaceutical compositions of this invention can be used as therapeutic or prophylactic agents. They are particularly well-suited for treatment of many inflammatory and autoimmune diseases.
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- Cell adhesion inhibitors
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The present invention relates to novel compounds that are useful for inhibition and prevention of cell adhesion and cell adhesion-mediated pathologies. This invention also relates to pharmaceutical formulations comprising these compounds and methods of using them for inhibition and prevention of cell adhesion and cell adhesion-mediated pathologies. The compounds and pharmaceutical compositions of this invention can be used as therapeutic or prophylactic agents. They are particularly well-suited for treatment of many inflammatory and autoimmune diseases.
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