High-Throughput Platform for Novel Reaction Discovery.

Detecting the formation of new chemical bonds in high-throughput synthesis is limited by the efficiency and scalability of reaction product detection, as conventional methods for isolating product from reaction mixtures are time consuming and labor intensive. Here, we report a miniaturizable purification method that enables the rapid, high-throughput isolation of quaternary ammonium-tagged products from reaction mixtures with excellent purity using inexpensive equipment that easily can be set up in a typical organic chemistry laboratory. This novel purification technique enabled us to establish a high-throughput reaction discovery platform. We validated this platform in a screen of 1536 reactions, and one previously unreported transformation was identified.

Carbonylation of Difluoroalkyl Bromides Catalyzed by Palladium.

Although important progress has been made in the fluoroalkylation reactions, the transition-metal-catalyzed carbonylative fluoroalkylation reaction remains challenging so far. Herein, we report the first example of a Pd-catalyzed carbonylation of difluoroalkyl bromides with (hetero)arylboronic acids under one atmosphere pressure of CO. The reaction can also be extended to the aryl potassium trifluoroborate salts. The advantages of this protocol are synthetic simplicity, broad substrate scope, and excellent functional group compatibility. The resulting difluoroalkyl ketones can serve as versatile building blocks for the synthesis of various useful fluorinated compounds.

Heparan sulfate assists SARS-CoV-2 in cell entry and can be targeted by approved drugs in vitro.

The cell entry of SARS-CoV-2 has emerged as an attractive drug repurposing target for COVID-19. Here we combine genetics and chemical perturbation to demonstrate that ACE2-mediated entry of SARS-Cov and CoV-2 requires the cell surface heparan sulfate (HS) as an assisting cofactor: ablation of genes involved in HS biosynthesis or incubating cells with a HS mimetic both inhibit Spike-mediated viral entry. We show that heparin/HS binds to Spike directly, and facilitates the attachment of Spike-bearing viral particles to the cell surface to promote viral entry. We screened approved drugs and identified two classes of inhibitors that act via distinct mechanisms to target this entry pathway. Among the drugs characterized, Mitoxantrone is a potent HS inhibitor, while Sunitinib and BNTX disrupt the actin network to indirectly abrogate HS-assisted viral entry. We further show that drugs of the two classes can be combined to generate a synergized activity against SARS-CoV-2-induced cytopathic effect. Altogether, our study establishes HS as an attachment factor that assists SARS coronavirus cell entry and reveals drugs capable of targeting this important step in the viral life cycle.

Heparan sulfate assists SARS-CoV-2 in cell entry and can be targeted by approved drugs in vitro.

The cell entry of SARS-CoV-2 has emerged as an attractive drug repurposing target for COVID-19. Here we combine genetics and chemical perturbation to demonstrate that ACE2-mediated entry of SARS-CoV and CoV-2 requires the cell surface heparan sulfate (HS) as an assisting cofactor: ablation of genes involved in HS biosynthesis or incubating cells with a HS mimetic both inhibit Spike-mediated viral entry. We show that heparin/HS binds to Spike directly, facilitates the attachment of viral particles to the cell surface to promote cell entry. We screened approved drugs and identified two classes of inhibitors that act via distinct mechanisms to target this entry pathway. Among the drugs characterized, Mitoxantrone is a potent HS inhibitor, while Sunitinib and BNTX disrupt the actin network to indirectly abrogate HS-assisted viral entry. We further show that drugs of the two classes can be combined to generate a synergized activity against SARS-CoV-2-induced cytopathic effect. Altogether, our study establishes HS as an attachment factor that assists SARS coronavirus cell entry, and reveals drugs capable of targeting this important step in the viral life cycle.

Highly Selective Pd-Catalyzed Direct C-F Bond Arylation of Polyfluoroarenes.

A directing-group-free palladium-catalyzed direct arylation of simple polyfluoroarenes with arylboronic acids through selective C-F bond activation is described. The combination of Pd(OAc)2 with BrettPhos was identified as an efficient catalytic system to promote the reaction with high regioselectivity and broad substrate scope. Preliminary mechanistic studies reveal that the oxidative addition of Pd to the C-F bond is involved in the catalytic cycle.

Copper-Catalyzed Direct Propargylation of Polyfluoroarenes with Secondary Propargyl Phosphates.

A copper-catalyzed direct propargylation of polyfluoroarenes with secondary propargyl phosphates has been developed. The reaction proceeds under mild reaction conditions with high efficiency and regioselectivity and provides a concise and straightforward method for the synthesis of polyfluoroarylated derivatives of interest in both life and materials science.