Highly anti-Selective Asymmetric Aldol Reactions Using Chiral Zirconium Catalysts. Improvement of Activities, Structure of the Novel Zirconium Complexes, and Effect of a Small Amount of Water for the Preparation of the Catalysts
- 8 March 2002
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 124 (13) , 3292-3302
- https://doi.org/10.1021/ja016293t
Abstract
Catalytic asymmetric aldol reactions of silyl enol ethers with aldehydes (Mukaiyama aldol reactions) have been performed using novel chiral zirconium catalysts. The reactions proceeded in high yields under mild conditions, and anti-adducts were obtained in high diastereo- and enantioselectivities. The catalysts were first prepared from zirconium(IV) tert-butoxide (Zr(OtBu)4), (R)-3,3‘-diiodo-1,1‘-binaphthalene-2,2‘-diol ((R)-3,3‘-I2BINOL), a primary alcohol, and a small amount of water. It was revealed that the primary alcohol played an important role in completing the catalytic cycle and that a small amount of water was essential for obtaining high selectivities. Moreover, activities of the chiral zirconium catalysts were enhanced by using new ligands, (R)-3,3‘-I2-6,6‘-X2BINOL (X = Br, I, C2F5), and it has been shown that even aldol reactions of less reactive substrates proceeded smoothly using the novel zirconium catalysts. Finally, NMR studies of these catalysts were performed, which suggested that the catalyst would form a dimeric structure and that the water affected the catalyst formation.Keywords
This publication has 24 references indexed in Scilit:
- Enantioselective Mannich-Type Reactions Using a Novel Chiral Zirconium Catalyst for the Synthesis of Optically Active β-Amino Acid DerivativesJournal of the American Chemical Society, 2000
- Chiral Catalyst Optimization Using Both Solid-Phase and Liquid-Phase Methods in Asymmetric Aza Diels−Alder ReactionsOrganic Letters, 2000
- A Switch of Enantiofacial Selectivities Using Designed Similar Chiral Ligands in Zirconium-Catalyzed Asymmetric Aza Diels−Alder ReactionsThe Journal of Organic Chemistry, 1999
- Efficient catalytic enantioselective mannich-type reactions using a zirconium-bis(binaphthol)methane complexTetrahedron Letters, 1999
- Chiral Zirconium-Catalyzed Asymmetric Mannich-Type Reactions Using Acylhydrazones as Imine EquivalentsChemistry Letters, 1998
- The First Enantioselective Aza-Diels-Alder Reactions of Imino Dienophiles on Use of a Chiral Zirconium CatalystAngewandte Chemie International Edition in English, 1998
- Catalytic Asymmetric Synthesis of Both Syn- and Anti-β-Amino AlcoholsJournal of the American Chemical Society, 1998
- Direct Catalytic Asymmetric Aldol Reactions of Aldehydes with Unmodified KetonesAngewandte Chemie International Edition in English, 1997
- Catalytic Enantioselective Mannich-Type Reactions Using a Novel Chiral Zirconium CatalystJournal of the American Chemical Society, 1997
- Asymmetric Catalytic Aldol-type Reaction with Ketene Silyl Acetals: Possible Intervention of the Silatropic Ene PathwayJournal of the American Chemical Society, 1994