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Chiral crown conformation of Rh(2)(S-PTTL)(4): enantioselective cyclopropanation with alpha-alkyl-alpha-diazoesters.
J Am Chem Soc. 2009 Jun 03; 131(21):7230-1.JA

Abstract

Herein, we provide crystallographic and computational evidence that Hashimoto's Rh(2)(S-PTTL)(4) catalyst adopts a "chiral crown" conformation with a reactive chiral face and an unreactive achiral face. In Rh(2)(S-PTTL)(4), all four tert-butyl groups are aligned on the same face of the catalyst, and each C-(t-Bu) bond is roughly parallel to the central Rh-Rh bond. This orients the four phthalimido groups on the opposite face of the catalyst. Also described is an enantioselective and diastereoselective protocol for intermolecular Rh(2)(S-PTTL)(4)-catalyzed cyclopropanation using alpha-alkyl-alpha-diazoesters. Intermolecular cyclopropanation is selective over two competing intramolecular pathways: C-H insertion and beta-hydride elimination. On the basis of density functional theory calculations and the Davies-Singleton model for cyclopropanation, a model for asymmetric induction is proposed.

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Authors+Show Affiliations

DeAngelis A
Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
Dmitrenko O
No affiliation info available
Yap GP
No affiliation info available
Fox JM
No affiliation info available

MeSH

CatalysisCyclopropanesDiazonium CompoundsEstersModels, MolecularMolecular ConformationOrganometallic CompoundsRhodiumStereoisomerism

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

19469571

Citation

DeAngelis, Andrew, et al. "Chiral Crown Conformation of Rh(2)(S-PTTL)(4): Enantioselective Cyclopropanation With Alpha-alkyl-alpha-diazoesters." Journal of the American Chemical Society, vol. 131, no. 21, 2009, pp. 7230-1.
DeAngelis A, Dmitrenko O, Yap GP, et al. Chiral crown conformation of Rh(2)(S-PTTL)(4): enantioselective cyclopropanation with alpha-alkyl-alpha-diazoesters. J Am Chem Soc. 2009;131(21):7230-1.
DeAngelis, A., Dmitrenko, O., Yap, G. P., & Fox, J. M. (2009). Chiral crown conformation of Rh(2)(S-PTTL)(4): enantioselective cyclopropanation with alpha-alkyl-alpha-diazoesters. Journal of the American Chemical Society, 131(21), 7230-1. https://doi.org/10.1021/ja9026852
DeAngelis A, et al. Chiral Crown Conformation of Rh(2)(S-PTTL)(4): Enantioselective Cyclopropanation With Alpha-alkyl-alpha-diazoesters. J Am Chem Soc. 2009 Jun 3;131(21):7230-1. PubMed PMID: 19469571.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Chiral crown conformation of Rh(2)(S-PTTL)(4): enantioselective cyclopropanation with alpha-alkyl-alpha-diazoesters. AU - DeAngelis,Andrew, AU - Dmitrenko,Olga, AU - Yap,Glenn P A, AU - Fox,Joseph M, PY - 2009/5/28/entrez PY - 2009/5/28/pubmed PY - 2009/8/1/medline SP - 7230 EP - 1 JF - Journal of the American Chemical Society JO - J Am Chem Soc VL - 131 IS - 21 N2 - Herein, we provide crystallographic and computational evidence that Hashimoto's Rh(2)(S-PTTL)(4) catalyst adopts a "chiral crown" conformation with a reactive chiral face and an unreactive achiral face. In Rh(2)(S-PTTL)(4), all four tert-butyl groups are aligned on the same face of the catalyst, and each C-(t-Bu) bond is roughly parallel to the central Rh-Rh bond. This orients the four phthalimido groups on the opposite face of the catalyst. Also described is an enantioselective and diastereoselective protocol for intermolecular Rh(2)(S-PTTL)(4)-catalyzed cyclopropanation using alpha-alkyl-alpha-diazoesters. Intermolecular cyclopropanation is selective over two competing intramolecular pathways: C-H insertion and beta-hydride elimination. On the basis of density functional theory calculations and the Davies-Singleton model for cyclopropanation, a model for asymmetric induction is proposed. SN - 1520-5126 UR - https://www.unboundmedicine.com/medline/citation/19469571/Chiral_crown_conformation_of_Rh_2__S_PTTL__4_:_enantioselective_cyclopropanation_with_alpha_alkyl_alpha_diazoesters_ L2 - https://doi.org/10.1021/ja9026852 DB - PRIME DP - Unbound Medicine ER -