Biocatalytic Promiscuity of Lipases in Carbon‐Phosphorus Bond Formation

ChemCatChem ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2554-2558 ◽  
Author(s):  
Dominik Koszelewski ◽  
Ryszard Ostaszewski
Keyword(s):  
Bond Formation ◽  
Biocatalytic Promiscuity

scholarly journals Enzymatic C-N Bond Formation via Aerobic Nitroso Ene Reactions

2021 ◽  
Author(s):  
Jan Deska ◽  
Christina Jäger
Keyword(s):  
Bond Formation ◽  
Reactive Intermediates ◽  
Hydroxamic Acids ◽  
Reaction Pathways ◽  
Ene Reactions ◽  
High Yields ◽  
Aqueous Conditions ◽  
Biocatalytic Promiscuity

<p><i>A novel biocatalytic protocol enables the direct and selective introduction of nitrogen functionalities via activation of allylic C-H bonds. Utilizing an oxidase/peroxidase couple for the formal dehydrogenation of N-hydroxycarbamates and hydroxamic acids with air as terminal oxidant, acylnitroso species are generated under particularly mild aqueous conditions. The reactive intermediates undergo C-N bond formation through an ene-type mechanism and provide high yields both in intramolecular and intermolecular enzymatic aminations. Investigations on alternative reaction pathways and labelling studies provide more insights into this unprecedented biocatalytic promiscuity of classical oxidoreductases as catalysts for nitroso ene-based transformations.</i></p>

Enzymatic C-N Bond Formation via Aerobic Nitroso Ene Reactions

2021 ◽  
Author(s):  
Jan Deska ◽  
Christina Jäger
Keyword(s):  
Bond Formation ◽  
Reactive Intermediates ◽  
Hydroxamic Acids ◽  
Reaction Pathways ◽  
Ene Reactions ◽  
High Yields ◽  
Aqueous Conditions ◽  
Biocatalytic Promiscuity

<p><i>A novel biocatalytic protocol enables the direct and selective introduction of nitrogen functionalities via activation of allylic C-H bonds. Utilizing an oxidase/peroxidase couple for the formal dehydrogenation of N-hydroxycarbamates and hydroxamic acids with air as terminal oxidant, acylnitroso species are generated under particularly mild aqueous conditions. The reactive intermediates undergo C-N bond formation through an ene-type mechanism and provide high yields both in intramolecular and intermolecular enzymatic aminations. Investigations on alternative reaction pathways and labelling studies provide more insights into this unprecedented biocatalytic promiscuity of classical oxidoreductases as catalysts for nitroso ene-based transformations.</i></p>

Stereodivergent Alkyne Hydrofluorination Using a Simple Practical Reagent

2020 ◽  
Author(s):  
Rui Guo ◽  
Xiaotian Qi ◽  
Hengye Xiang ◽  
Paul Geaneoates ◽  
Ruihan Wang ◽  
...  
Keyword(s):  
Bond Formation ◽  
Biologically Active ◽  
Dft Studies ◽  
Thermodynamic Control ◽  
Important Goal ◽  
Peptide Bonds ◽  
Metal Free ◽  
Vinyl Cation ◽  
E And Z Isomers ◽  
Vinyl Fluorides

Vinyl fluorides play an important role in drug development as they serve as bioisosteres for peptide bonds and are found in a range of biologically active molecules. The discovery of safe, general and practical procedures to prepare vinyl fluorides remains an important goal and challenge for synthetic chemistry. Here we introduce an inexpensive and easily-handled reagent and report simple, scalable, and metal-free protocols for the regioselective and stereodivergent hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These conditions were suitable for a diverse collection of alkynes, including several highly-functionalized pharmaceutical derivatives. Mechanistic and DFT studies support C–F bond formation through a vinyl cation intermediate, with the (E)- and (Z)-hydrofluorination products forming under kinetic and thermodynamic control, respectively.<br>

Imine as a Linchpin Approach for Distal C(sp2)–H Functionalization

2020 ◽  
Author(s):  
Sukdev Bag ◽  
Sadhan Jana ◽  
Sukumar Pradhan ◽  
Suman Bhowmick ◽  
Nupur Goswami ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Bond Activation ◽  
Bond Formation ◽  
Ancillary Ligand ◽  
Significant Challenge ◽  
Site Selectivity ◽  
Directing Group ◽  
Covalently Linked ◽  
Complex Organic ◽  
Post Functionalization

<p>Despite the widespread applications of C–H functionalization, controlling site selectivity remains a significant challenge. Covalently attached directing group (DG) served as an ancillary ligand to ensure proximal <i>ortho</i>-, distal <i>meta</i>- and <i>para</i>-C-H functionalization over the last two decades. These covalently linked DGs necessitate two extra steps for a single C–H functionalization: introduction of DG prior to C–H activation and removal of DG post-functionalization. We introduce here a transient directing group for distal C(<i>sp<sup>2</sup></i>)-H functionalization <i>via</i> reversible imine formation. By overruling facile proximal C-H bond activation by imine-<i>N</i> atom, a suitably designed pyrimidine-based transient directing group (TDG) successfully delivered selective distal C-C bond formation. Application of this transient directing group strategy for streamlining the synthesis of complex organic molecules without any necessary pre-functionalization at the distal position has been explored.</p>

Carbon Dioxide-Mediated C(sp2)–H Arylation of Primary and Secondary Benzylamines

2018 ◽  
Author(s):  
Mohit Kapoor ◽  
Pratibha Chand-Thakuri ◽  
Michael Young
Keyword(s):  
Carbon Dioxide ◽  
Transition Metal ◽  
Bond Activation ◽  
Bond Formation ◽  
Carbon Bond ◽  
Chelate Effect ◽  
Free Amine ◽  
Carbon Carbon Bond ◽  
New Strategy ◽  
Metal Catalyzed

Carbon-carbon bond formation by transition metal-catalyzed C–H activation has become an important strategy to fabricate new bonds in a rapid fashion. Despite the pharmacological importance of <i>ortho</i>-arylbenzylamines, however, effective <i>ortho</i>-C–C bond formation from C–H bond activation of free primary and secondary benzylamines using Pd<sup>II</sup> remains an outstanding challenge. Presented herein is a new strategy for constructing <i>ortho</i>-arylated primary and secondary benzylamines mediated by carbon dioxide (CO<sub>2</sub>). The use of CO<sub>2</sub> is critical to allowing this transformation to proceed under milder conditions than previously reported, and that are necessary to furnish free amine products that can be directly used or elaborated without the need for deprotection. In cases where diarylation is possible, a chelate effect is demonstrated to facilitate selective monoarylation.

Radical Capture at Ni(II) Complexes: C-C, C-N, and C-O Bond Formation

2019 ◽  
Author(s):  
Abolghasem (Gus) Bakhoda ◽  
Stefan Wiese ◽  
Christine Greene ◽  
Bryan C. Figula ◽  
Jeffery A. Bertke ◽  
...  
Keyword(s):  
Functional Groups ◽  
Bond Formation ◽  
Dft Studies ◽  
Bond Forming ◽  
Aryl Amines ◽  
Shed Light ◽  
Competing Pathways

<p>The dinuclear b-diketiminato Ni<sup>II</sup><i>tert</i>-butoxide {[Me<sub>3</sub>NN]Ni}<sub>2</sub>(<i>μ</i>-O<i><sup>t</sup></i>Bu)<sub>2 </sub>(<b>2</b>), synthesized from [Me<sub>3</sub>NN]Ni(2,4-lutidine) (<b>1</b>) and di-<i>tert</i>-butylperoxide, is a versatile precursor for the synthesis of a series of Ni<sup>II</sup>complexes [Me<sub>3</sub>NN]Ni-FG to illustrate C-C, C-N, and C-O bond formation at Ni<sup>II </sup>via radicals. {[Me<sub>3</sub>NN]Ni}<sub>2</sub>(<i>μ</i>-O<i><sup>t</sup></i>Bu)<sub>2 </sub>reacts with nitromethane, alkyl and aryl amines, acetophenone, benzamide, ammonia and phenols to deliver corresponding mono- or dinuclear [Me<sub>3</sub>NN]Ni-FG species (FG = O<sub>2</sub>NCH<sub>2</sub>, R-NH, ArNH, PhC(O)NH, PhC(O)CH<sub>2</sub>, NH<sub>2</sub>and OAr). Many of these Ni<sup>II </sup>complexes are capable of capturing the benzylic radical PhCH(•)CH<sub>3 </sub>to deliver corresponding PhCH(FG)CH<sub>3 </sub>products featuring C-C, C-N or C-O bonds. DFT studies shed light on the mechanism of these transformations and suggest two competing pathways that depend on the nature of the functional groups. These radical capture reactions at [Ni<sup>II</sup>]-FG complexes outline key C-C, C-N, and C-O bond forming steps and suggest new families of nickel radical relay catalysts.</p>

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