Effect of Fifth Coordination in Catalytic Epoxidation by a Chiral Manganese Porphyrin

Effect of Fifth Coordination in Catalytic Epoxidation by a Chiral Manganese Porphyrin

Abstract The effect of multifarious organic bases in chiral manganese porphyrin catalyzed enantioselective alkene epoxidation was investigated. For substituted pyridines, the enantioselectivity of CIS-β-methylstyrene epoxidation follows a linear free energy relationship for pyridines bearing electro...

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Veröffentlicht in:Synlett 2002, Vol.2002 (9), p.1475-1478
Hauptverfasser: Lai, Tat-Shing, Ng, Kim-Ho, Liu, Hai-Yang, Chang, Chi K., Yeung, Lam-Lung
Format: Artikel
Sprache:eng
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Zusammenfassung:Abstract The effect of multifarious organic bases in chiral manganese porphyrin catalyzed enantioselective alkene epoxidation was investigated. For substituted pyridines, the enantioselectivity of CIS-β-methylstyrene epoxidation follows a linear free energy relationship for pyridines bearing electron-donating groups. Compared to the case of no amine additive, a significant improvement in enantio­selectivity from 43% ee to 81% ee for epoxidation of CIS-β-methylstyrene with a 86.5% stereospecificity were observed when DMAP and KHSO 5 were employed as axial ligand and oxidant respectively.
ISSN:0936-5214
1437-2096
DOI:10.1055/s-2002-33523