Development of the Commercial Manufacturing Process for Nirmatrelvir in 17 Months.

The advancement of nirmatrelvir, the active ingredient in Paxlovid, from discovery to emergency use authorization was achieved in just 17 months, requiring an unprecedented rate of chemical process development.

The Single-Component Flavin Reductase/Flavin-Dependent Halogenase AetF is a Versatile Catalyst for Selective Bromination and Iodination of Arenes and Olefins.

Flavin-dependent halogenases (FDHs) natively catalyze selective halogenation of electron rich aromatic and enolate groups. Nearly all FDHs reported to date require a separate flavin reductase to supply them with FADH2 , which complicates biocatalysis applications. In this study, we establish that the single component flavin reductase/flavin dependent halogenase AetF catalyzes halogenation of a diverse set of substrates using a commercially available glucose dehydrogenase to drive its halogenase activity. High site selectivity, activity on relatively unactivated substrates, and high enantioselectivity for atroposelective bromination and bromolactonization was demonstrated. Site-selective iodination and enantioselective cycloiodoetherification was also possible using AetF. The substrate and reaction scope of AetF suggest that it has the potential to greatly improve the utility of biocatalytic halogenation.

Redox-Neutral TEMPO Catalysis: Direct Radical (Hetero)Aryl C-H Di- and Trifluoromethoxylation.

Applications of TEMPO. catalysis for the development of redox-neutral transformations are rare. Reported here is the first TEMPO. -catalyzed, redox-neutral C-H di- and trifluoromethoxylation of (hetero)arenes. The reaction exhibits a broad substrate scope, has high functional-group tolerance, and can be employed for the late-stage functionalization of complex druglike molecules. Kinetic measurements, isolation and resubjection of catalytic intermediates, UV/Vis studies, and DFT calculations support the proposed oxidative TEMPO. /TEMPO+ redox catalytic cycle. Mechanistic studies also suggest that Li2 CO3 plays an important role in preventing catalyst deactivation. These findings will provide new insights into the design and development of novel reactions through redox-neutral TEMPO. catalysis.

Synthesis of Tri- and Difluoromethoxylated Compounds by Visible-Light Photoredox Catalysis.

Trifluoromethoxy (OCF3 ) and difluoromethoxy (OCF2 H) groups are fluorinated structural motifs that exhibit unique physicochemical characteristics. Incorporation of these substituents into organic molecules is a highly desirable approach used in medicinal chemistry and drug discovery processes to alter the properties of a parent compound. Recently, tri- and difluoromethyl ethers have received increasing attention and several innovative strategies to access these valuable functional groups have been developed. The focus of this Minireview is the use of visible-light photoredox catalysis in the synthesis of tri- and difluoromethyl ethers. Recent photocatalytic strategies for the formation of O-CF3 , C-OCF3, O-CF2 H, and C-OCF2 H bonds as well as other transformations leading to the construction of ORF groups are discussed herein.

Catalytic radical difluoromethoxylation of arenes and heteroarenes.

Intermolecular C-H difluoromethoxylation of (hetero)arenes remains a long-standing and unsolved problem in organic synthesis. Herein, we report the first catalytic protocol employing a redox-active difluoromethoxylating reagent 1a and photoredox catalysts for the direct C-H difluoromethoxylation of (hetero)arenes. Our approach is operationally simple, proceeds at room temperature, and uses bench-stable reagents. Its synthetic utility is highlighted by mild reaction conditions that tolerate a wide variety of functional groups and biorelevant molecules. Experimental and computational studies suggest single electron transfer (SET) from excited photoredox catalysts to 1a forming a neutral radical intermediate that liberates the OCF2H radical exclusively. Addition of this radical to (hetero)arenes gives difluoromethoxylated cyclohexadienyl radicals that are oxidized and deprotonated to afford the products of difluoromethoxylation.

Redox-Active Reagents for Photocatalytic Generation of the OCF3 Radical and (Hetero)Aryl C-H Trifluoromethoxylation.

The trifluoromethoxy (OCF3 ) radical is of great importance in organic chemistry. Yet, the catalytic and selective generation of this radical at room temperature and pressure remains a longstanding challenge. Herein, the design and development of a redox-active cationic reagent (1) that enables the formation of the OCF3 radical in a controllable, selective, and catalytic fashion under visible-light photocatalytic conditions is reported. More importantly, the reagent allows catalytic, intermolecular C-H trifluoromethoxylation of a broad array of (hetero)arenes and biorelevant compounds. Experimental and computational studies suggest single electron transfer (SET) from excited photoredox catalysts to 1 resulting in exclusive liberation of the OCF3 radical. Addition of this radical to (hetero)arenes gives trifluoromethoxylated cyclohexadienyl radicals that are oxidized and deprotonated to afford the products of trifluoromethoxylation.

Transition-metal-free C-H amidation and chlorination: synthesis of N/N'-mono-substituted imidazopyridin-2-ones from N-pyridyl-N-hydroxylamine intermediates.

Non-symmetric 1,3-substituted imidazopyridin-2-ones are a common structural scaffold found among many biologically active molecules. Herein we report an efficient, mild, and transition-metal free C-H amidation strategy to access such a pyrido-fused cyclic urea framework in good yields and with a broad functional group tolerance.

Catalytic C-H Trifluoromethoxylation of Arenes and Heteroarenes.

The intermolecular C-H trifluoromethoxylation of arenes remains a long-standing and unsolved problem in organic synthesis. Herein, we report the first catalytic protocol employing a novel trifluoromethoxylating reagent and redox-active catalysts for the direct (hetero)aryl C-H trifluoromethoxylation. Our approach is operationally simple, proceeds at room temperature, uses easy-to-handle reagents, requires only 0.03 mol % of redox-active catalysts, does not need specialized reaction apparatus, and tolerates a wide variety of functional groups and complex structures such as sugars and natural product derivatives. Importantly, both ground-state and photoexcited redox-active catalysts are effective. Detailed computational and experimental studies suggest a unique reaction pathway where photoexcitation of the trifluoromethoxylating reagent releases the OCF3 radical that is trapped by (hetero)arenes. The resulting cyclohexadienyl radicals are oxidized by redox-active catalysts and deprotonated to form the desired products of trifluoromethoxylation.

Recent Development of Catalytic Trifluoromethoxylation Reactions.

Trifluoromethoxy (OCF3) group exhibits unique properties, which render it a highly desirable structural motif in life and materials sciences. The numbers of newly synthesized trifluoromethyl ethers are booming as new synthetic methods are constantly being developed to access these valuable compounds. This Review summarizes recent catalytic approaches towards preparation of trifluoromethyl ethers. Alkene, allylic, benzylic, and aryl trifluoromethoxylation reactions are discussed herein.

Selective C-O bond formation via a photocatalytic radical coupling strategy: access to perfluoroalkoxylated (ORF) arenes and heteroarenes.

Development of an efficient process that employs commercially available and cost effective reagents for the synthesis of perfluoroalkoxylated aromatic compounds (Ar-ORF) remains a daunting challenge in organic synthesis. Herein, we report the first catalytic protocol using readily available perfluoroalkyl iodides (RFI) and N-(hetero)aryl-N-hydroxylamides to access a wide range of perfluoroalkoxylated (hetero)arenes. Mild reaction conditions allow for selective O-RF bond formation over a broad substrate scope and are tolerant of a wide variety of functional groups. Mechanistic studies suggest the formation and recombination of persistent N-hydroxyl radicals and transient RF radicals under photocatalytic reaction conditions to generate N-ORF compounds that rearrange to afford the desired products.

Access to a new class of synthetic building blocks via trifluoromethoxylation of pyridines and pyrimidines.

Since the first synthesis of trifluoromethyl ethers in 1935, the trifluoromethoxy (OCF3) group has made a remarkable impact in medicinal, agrochemical, and materials science research. However, our inability to facilely incorporate the OCF3 group into molecules, especially heteroaromatics, has limited its potential across a broad spectrum of technological applications. Herein, we report a scalable and operationally simple protocol for regioselective trifluoromethoxylation of a wide range of functionalized pyridines and pyrimidines under mild reaction conditions. The trifluoromethoxylated products are useful scaffolds that can be further elaborated by amidation and palladium-catalysed cross coupling reactions. Mechanistic studies suggest that a radical O-trifluoromethylation followed by the OCF3-migration reaction pathway is operable. Given the unique properties of the OCF3 group and the ubiquity of pyridine and pyrimidine in biologically active molecules and functional materials, trifluoromethoxylated pyridines and pyrimidines could serve as valuable building blocks for the discovery and development of new drugs, agrochemicals, and materials.

Synthesis of Trifluoromethoxylated (Hetero)Arenes via OCF3 Migration.

Incorporation of the OCF3 group into organic molecules, especially aromatic and heteroaromatic compounds, is recognized as one of the major challenges in synthetic organic chemistry. Although many attempts have been made to develop efficient trifluoromethoxylation strategies, most of the current approaches still require use of highly toxic, thermally unstable reagents, or impractical reaction conditions. Herein, we highlight a recent contribution from our group towards the synthesis of (hetero)aryltrifluoromethyl ethers. Our protocol is scalable, operationally simple, and allows an easy access to a wide range of synthetically useful ortho-OCF3 aniline derivatives, as well as functionalized trifluoromethoxylated pyridines and pyrimidines under mild reaction conditions.