Enantioselective arylation of aldehydes catalyzed by a soluble optically active polybinaphthols ligand |
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Authors: | Xiaobo Huang Linglin Wu Lili Zong Yixiang Cheng |
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Institution: | a Key Lab of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China b College of Chemistry and Materials Engineering, Wenzhou University,Wenzhou 325027, PR China |
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Abstract: | A soluble chiral polymer ligand was synthesized by the polymerization of (R)-6,6′-dibutyl-3,3′-diformyl-2,2′-binaphthol (R-M-1) with 2,5-diaminopyridine (M-2) via a nucleophilic addition-elimination reaction. While arylboronic acids were used as the source of the transferable aryl group, the chiral polybinaphthols ligand in combination with Et2Zn without Ti(OiPr)4 exhibited higher enantioselectivity in asymmetric addition to aromatic aldehydes than alphatic aldehydes. When aromatic aldehydes with electron-withdrawing groups were chosen as substrates, the resulting diarylmethanols were produced in higher ee values than those with electron-donating groups as substrates. 2-Naphthaldehyde used as a substrate afforded product in 95% ee, which could be ascribed to the steric effect influence on this asymmetric arylation reaction. Moreover, the chiral polymer was easily recovered and reused, but exhibited a decrease of enantioselectivity in the third recycle. |
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Keywords: | Chiral BINOL-based polymer Asymmetric addition Enantioselectivity |
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