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Catalytic asymmetric aldol reactions in aqueous media using chiral bis-pyridino-18-crown-6-rare earth metal triflate complexes.
J Am Chem Soc. 2003 Mar 12; 125(10):2989-96.JA

Abstract

Catalytic asymmetric aldol reactions in aqueous media have been developed using Pr(OTf)(3) and chiral bis-pyridino-18-crown-6 1. In the asymmetric aldol reaction using rare earth metal triflates (RE(OTf)(3)) and 1, slight changes in the ionic diameters of the metal cations greatly affected the diastereo- and enantioselectivities of the products. The substituents (MeO, Br) at the 4-position of the pyridine rings of the crown ether did not significantly affect the selectivities in the asymmetric aldol reaction, although they affected the binding ability of the crown ether with RE cations and the catalytic activity of Pr(OTf)(3)-crown ether complexes. From X-ray structures of RE(NO(3))(3)-crown ether complexes, it was found that they had similar structures regardless of the RE cations and the crown ethers used. Accordingly, the binding ability of the crown ether with the RE cation and the catalytic activity of the complex are important for attaining high selectivity in the asymmetric aldol reaction. Various aromatic and alpha,beta-unsaturated aldehydes and silyl enol ethers derived from ketones and a thioester can be employed in the catalytic asymmetric aldol reactions using Pr(OTf)(3) and 1, to provide the aldol adducts in good to high yields and stereoselectivities. In the case using the silyl enol ether derived from the thioester, 2,6-di-tert-butylpyridine significantly improved the yields of the aldol adducts.

Authors+Show Affiliations

Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

12617666

Citation

Hamada, Tomoaki, et al. "Catalytic Asymmetric Aldol Reactions in Aqueous Media Using Chiral Bis-pyridino-18-crown-6-rare Earth Metal Triflate Complexes." Journal of the American Chemical Society, vol. 125, no. 10, 2003, pp. 2989-96.
Hamada T, Manabe K, Ishikawa S, et al. Catalytic asymmetric aldol reactions in aqueous media using chiral bis-pyridino-18-crown-6-rare earth metal triflate complexes. J Am Chem Soc. 2003;125(10):2989-96.
Hamada, T., Manabe, K., Ishikawa, S., Nagayama, S., Shiro, M., & Kobayashi, S. (2003). Catalytic asymmetric aldol reactions in aqueous media using chiral bis-pyridino-18-crown-6-rare earth metal triflate complexes. Journal of the American Chemical Society, 125(10), 2989-96.
Hamada T, et al. Catalytic Asymmetric Aldol Reactions in Aqueous Media Using Chiral Bis-pyridino-18-crown-6-rare Earth Metal Triflate Complexes. J Am Chem Soc. 2003 Mar 12;125(10):2989-96. PubMed PMID: 12617666.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Catalytic asymmetric aldol reactions in aqueous media using chiral bis-pyridino-18-crown-6-rare earth metal triflate complexes. AU - Hamada,Tomoaki, AU - Manabe,Kei, AU - Ishikawa,Shunpei, AU - Nagayama,Satoshi, AU - Shiro,Motoo, AU - Kobayashi,Shū, PY - 2003/3/6/pubmed PY - 2003/3/6/medline PY - 2003/3/6/entrez SP - 2989 EP - 96 JF - Journal of the American Chemical Society JO - J Am Chem Soc VL - 125 IS - 10 N2 - Catalytic asymmetric aldol reactions in aqueous media have been developed using Pr(OTf)(3) and chiral bis-pyridino-18-crown-6 1. In the asymmetric aldol reaction using rare earth metal triflates (RE(OTf)(3)) and 1, slight changes in the ionic diameters of the metal cations greatly affected the diastereo- and enantioselectivities of the products. The substituents (MeO, Br) at the 4-position of the pyridine rings of the crown ether did not significantly affect the selectivities in the asymmetric aldol reaction, although they affected the binding ability of the crown ether with RE cations and the catalytic activity of Pr(OTf)(3)-crown ether complexes. From X-ray structures of RE(NO(3))(3)-crown ether complexes, it was found that they had similar structures regardless of the RE cations and the crown ethers used. Accordingly, the binding ability of the crown ether with the RE cation and the catalytic activity of the complex are important for attaining high selectivity in the asymmetric aldol reaction. Various aromatic and alpha,beta-unsaturated aldehydes and silyl enol ethers derived from ketones and a thioester can be employed in the catalytic asymmetric aldol reactions using Pr(OTf)(3) and 1, to provide the aldol adducts in good to high yields and stereoselectivities. In the case using the silyl enol ether derived from the thioester, 2,6-di-tert-butylpyridine significantly improved the yields of the aldol adducts. SN - 0002-7863 UR - https://www.unboundmedicine.com/medline/citation/12617666/Catalytic_asymmetric_aldol_reactions_in_aqueous_media_using_chiral_bis_pyridino_18_crown_6_rare_earth_metal_triflate_complexes_ L2 - https://doi.org/10.1021/ja028698z DB - PRIME DP - Unbound Medicine ER -
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