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Azzena, Ugo Gavino and Dettori, Giovanna and Mascia, Ilaria and Pisano, Luisa and Pittalis, Mario (2007) Ion pairing effects on the regioselectivity of arylic versus benzylic C-O bond reductive cleavage: synthetic applications. Tetrahedron, Vol. 63 (48), p. 11998-12006. ISSN 0040-4020. Article. Full text not available from this repository. DOI: 10.1016/j.tet.2007.09.010 AbstractThe regioselectivity of the reductive cleavage of 3,4,5-trimethoxybenzyl methyl ether strongly depends on the alkali metal employed as a reducing agent and solvent effects. Reactions run using Na as a reducing agent led to aromatic C(4)-O bond cleavage, whilst reductions run in the presence of Na/15-crown-5, or using Li as a reducing agent, led to highly regioselective benzylic C-O bond cleavage. This regioselectivity turnaround is discussed in terms of major solvent effects affecting the fragmentation paths of a common reaction intermediate. Synthetic applications of these findings led to the synthesis of biologically active compounds, like 2,5-dialkyl-substituted resorcinols, or 1-(3,4,5-trimethoxyphenyl)-2-arylethanes structurally related to combretastatin.
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