- An Enzymatic Platform for the Highly Enantioselective and Stereodivergent Construction of Cyclopropyl-δ-lactones
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Abiological enzymes offers new opportunities for sustainable chemistry. Herein, we report the development of biological catalysts derived from sperm whale myoglobin that exploit a carbene transfer mechanism for the asymmetric synthesis of cyclopropane-fused-δ-lactones, which are key structural motifs found in many biologically active natural products. While hemin, wild-type myoglobin, and other hemoproteins are unable to catalyze this reaction, the myoglobin scaffold could be remodeled by protein engineering to permit the intramolecular cyclopropanation of a broad spectrum of homoallylic diazoacetate substrates in high yields and with up to 99 % enantiomeric excess. Via an alternate evolutionary trajectory, a stereodivergent biocatalyst was also obtained for affording mirror-image forms of the desired bicyclic products. In combination with whole-cell transformations, the myoglobin-based biocatalyst was used for the asymmetric construction of a cyclopropyl-δ-lactone scaffold at a gram scale, which could be further elaborated to furnish a variety of enantiopure trisubstituted cyclopropanes.
- Chandgude, Ajay L.,Fasan, Rudi,Liu, Ningyu,Ren, Xinkun
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p. 21634 - 21639
(2020/09/23)
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- Nickel Catalyzed Regio-, Diastereo-, and Enantioselective Cross-Coupling of 3,4-Epoxyalcohol with Aryl Iodides
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The first catalytic, regioselective cross-coupling of 3,4-epoxyalcohol with aryl iodides is reported. The combination of NiCl2·DME and a newly developed C2-symmetric oxazoline ligand plays a key role in selective ring opening of seve
- Banerjee, Amit,Yamamoto, Hisashi
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p. 4363 - 4366
(2017/08/23)
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- Alkene Dioxygenation with Malonoyl Peroxides: Synthesis of γ-Lactones, Isobenzofuranones, and Tetrahydrofurans
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Treatment of homoallylic alcohols or carboxylic acids with malonoyl peroxide 1 provides a stereoselective method for the preparation of tetrahydrofurans, γ-lactones, and isobenzofuranones in 44-82% yield and up to 27:1 trans selectivity. Application of this simple and effective heterocyclization in the synthesis of the antidepressant citalopram is also described.
- Alamillo-Ferrer, Carla,Karabourniotis-Sotti, Marianna,Kennedy, Alan R.,Campbell, Matthew,Tomkinson, Nicholas C. O.
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p. 3102 - 3105
(2016/07/13)
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- Asymmetric 5-endo chloroetherification of homoallylic alcohols toward the synthesis of chiral β-chlorotetrahydrofurans
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An asymmetric 5-endo chloroetherification of homoallylic alcohols is successfully developed that employs an easily available quaternary ammonium salt derived from cinchonine as a conventional organocatalyst. This approach provides ready access to β-chloro
- Zeng, Xianghua,Miao, Chengxia,Wang, Shoufeng,Xia, Chungu,Sun, Wei
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p. 2418 - 2420
(2013/04/10)
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