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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.
J Am Chem Soc. 2002 Apr 03; 124(13):3292-302.JA

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(O(t)Bu)(4)), (R)-3,3'-diiodo-1,1'-binaphthalene-2,2'-diol ((R)-3,3'-I(2)BINOL), 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'-I(2)-6,6'-X(2)BINOL (X = Br, I, C(2)F(5)), 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.

Authors+Show Affiliations

Yamashita Y
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Ishitani H
No affiliation info available
Shimizu H
No affiliation info available
Kobayashi S
No affiliation info available

MeSH

AlcoholsAldehydesCatalysisMagnetic Resonance SpectroscopyNaphtholsOrganometallic CompoundsStereoisomerismWaterZirconium

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

11916413

Citation

Yamashita, Yasuhiro, et al. "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." Journal of the American Chemical Society, vol. 124, no. 13, 2002, pp. 3292-302.
Yamashita Y, Ishitani H, Shimizu H, et al. 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. J Am Chem Soc. 2002;124(13):3292-302.
Yamashita, Y., Ishitani, H., Shimizu, H., & Kobayashi, S. (2002). 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. Journal of the American Chemical Society, 124(13), 3292-302.
Yamashita Y, et al. 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. J Am Chem Soc. 2002 Apr 3;124(13):3292-302. PubMed PMID: 11916413.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - 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. AU - Yamashita,Yasuhiro, AU - Ishitani,Haruro, AU - Shimizu,Haruka, AU - Kobayashi,Shū, PY - 2002/3/28/pubmed PY - 2002/6/20/medline PY - 2002/3/28/entrez SP - 3292 EP - 302 JF - Journal of the American Chemical Society JO - J Am Chem Soc VL - 124 IS - 13 N2 - 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(O(t)Bu)(4)), (R)-3,3'-diiodo-1,1'-binaphthalene-2,2'-diol ((R)-3,3'-I(2)BINOL), 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'-I(2)-6,6'-X(2)BINOL (X = Br, I, C(2)F(5)), 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. SN - 0002-7863 UR - https://www.unboundmedicine.com/medline/citation/11916413/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_ L2 - https://doi.org/10.1021/ja016293t DB - PRIME DP - Unbound Medicine ER -