We report the discovery of an unusual halohydrin dehalogenase, HHDHamb, that can work under relatively low acidic conditions and extremely low temperatures for the bio-nitration of epoxides using nitrite as a nitrating agent. The bio-nitration strategy exhibits high chemo-, regio-, and enantioselectivity, catalyzing the kinetic resolution of various epoxides to enantiopure β-nitroalcohols with nitro-bearing stereocenters in up to 41 % isolated yield and >99 % enantiomeric excess (ee). Additionally, the bio-nitration method displays a high reaction efficiency and can be performed on a gram scale. We also solved the crystal structure of HHDHamb to understand the possible structural determinants of chemoselectivity control in the bio-nitration reaction.
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http://dx.doi.org/10.1002/anie.202205790 | DOI Listing |
Angew Chem Int Ed Engl
September 2022
Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, China.
We report the discovery of an unusual halohydrin dehalogenase, HHDHamb, that can work under relatively low acidic conditions and extremely low temperatures for the bio-nitration of epoxides using nitrite as a nitrating agent. The bio-nitration strategy exhibits high chemo-, regio-, and enantioselectivity, catalyzing the kinetic resolution of various epoxides to enantiopure β-nitroalcohols with nitro-bearing stereocenters in up to 41 % isolated yield and >99 % enantiomeric excess (ee). Additionally, the bio-nitration method displays a high reaction efficiency and can be performed on a gram scale.
View Article and Find Full Text PDFACS Omega
October 2021
Department of Organic Chemistry, University of Pannonia, 8200 Veszprém, Egyetem u. 10, Hungary.
The ring opening of 2α,3α- and 2β,3β-epoxy-5α-androstan-17-one with halide reagents (AlCl, TMSCl, LiCl, and LiBr) was investigated using imidazolium ionic liquids in the dual role of solvent and catalyst. The application of the ionic liquid was shown to result in an increase in the amount of the unusual diequatorial halohydrins especially at temperatures above 100 °C. With a careful choice of reaction conditions, the latter derivatives could be produced with 43-96% selectivity depending on the nature of the halide ion.
View Article and Find Full Text PDFOrg Lett
September 2018
Department of Chemistry , University of Toronto, 80 St. George Street , Toronto , Ontario M5S 3H6 , Canada.
A new mode of catalysis of the semipinacol rearrangement of 2,3-epoxy alcohols is described. In combination with a halide salt additive, diarylborinic acids promote a Type II rearrangement that occurs with net retention of configuration. This unusual stereochemical outcome is consistent with a mechanism involving regioselective ring opening of the epoxy alcohol by halide, followed by rearrangement of the resulting halohydrin-derived borinic ester.
View Article and Find Full Text PDFJ Org Chem
November 2016
Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, U.K.
1,4-Dioxenes present interesting potential as synthetic intermediates and as unusual motifs for incorporation into biologically active compounds. Here, an efficient synthesis of functionalized 1,4-dioxenes is achieved in two steps. Using keto-diazo compounds, a ruthenium catalyzed O-H insertion with β-halohydrins followed by treatment with base results in cyclization with excellent selectivity, through O-alkylation of the keto-enolate.
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