Nitrosonium ion catalysis: aerobic, metal-free cross-dehydrogenative carbon–heteroatom bond formation

Catalytic cross-dehydrogenative coupling of heteroarenes with thiophenols and phenothiazines has been developed under mild and environmentally benign reaction conditions

Merging enzymes with chemocatalysis for amide bond synthesis

Amides are one of the most fundamental chemical bonds in nature. In addition to proteins and other metabolites, many valuable synthetic products comprise amide bonds. Despite this, there is a need for more sustainable amide synthesis. Herein, we report an integrated next generation multi-catalytic system, merging nitrile hydratase enzymes with a Cu-catalysed N-arylation reaction in a single reaction vessel, for the construction of ubiquitous amide bonds. This synergistic one-pot combination of chemo- and biocatalysis provides an amide bond disconnection to precursors, that are orthogonal to those in classical amide synthesis, obviating the need for protecting groups and delivering amides in a manner unachievable using existing catalytic regimes. Our integrated approach also affords broad scope, very high (molar) substrate loading, and has excellent functional group tolerance, telescoping routes to natural product derivatives, drug molecules, and challenging chiral amides under environmentally friendly conditions at scale

Development of efficient methods for metal-free C–H bond functionalization

The development of novel and efficient methods for the transition metal-free functionalization of inert and abundant C–H bonds offers striking advantages in terms of step- and atom economy under environmentally benign reaction conditions. Metal-free reactions serve as environmentally friendly substitutes for cost intensive and harmful transition metal-catalyzed reactions. However, oxidative coupling reactions under metal-free conditions face some unsolved problems. High molecular weight oxidants, which are often used in stoichiometric amounts, lead to the undesired generation of large quantities of waste. Additionally, some organic oxidants are toxic, explosive or corrosive. Consequently, the development of catalytic and metal-free methods for the functionalization of C–H bonds attracted significant interest. With the aim to develop novel transition metal-free reactions and to address the aforementioned challenges, different synthetic methods have been established

Discovery, characterization and engineering of ligases for amide synthesis.

From PubMed via Jisc Publications RouterHistory: received 2020-08-21, accepted 2021-03-11Publication status: ppublishCoronatine and related bacterial phytotoxins are mimics of the hormone jasmonyl-L-isoleucine (JA-Ile), which mediates physiologically important plant signalling pathways . Coronatine-like phytotoxins disrupt these essential pathways and have potential in the development of safer, more selective herbicides. Although the biosynthesis of coronatine has been investigated previously, the nature of the enzyme that catalyses the crucial coupling of coronafacic acid to amino acids remains unknown . Here we characterize a family of enzymes, coronafacic acid ligases (CfaLs), and resolve their structures. We found that CfaL can also produce JA-Ile, despite low similarity with the Jar1 enzyme that is responsible for ligation of JA and L-Ile in plants . This suggests that Jar1 and CfaL evolved independently to catalyse similar reactions-Jar1 producing a compound essential for plant development , and the bacterial ligases producing analogues toxic to plants. We further demonstrate how CfaL enzymes can be used to synthesize a diverse array of amides, obviating the need for protecting groups. Highly selective kinetic resolutions of racemic donor or acceptor substrates were achieved, affording homochiral products. We also used structure-guided mutagenesis to engineer improved CfaL variants. Together, these results show that CfaLs can deliver a wide range of amides for agrochemical, pharmaceutical and other applications

Boletín Clínico, Vol. 03, No. 06. Marzo

Biblioteca de la Facultad de Medicina de la Universidad de Antioquia y de la Academia de Medicina de Medellín * Sanidad de Medellín. Resolución No. 5 * Bubón climático algunas anotaciones clínicas y terapéuticas. Pag.335-358 * El tratamiento de la sífilis. Pag.359-371 * Fiebre perniciosa. (Observaciones clínicas). Pag.372-375 * Evolución del ornithodorus talaje. Pag.376-377 * Tesis de la Facultad. Enfermedad de Nicolas Favre y reacción de Frei. Pag.378-379 * Urografía intravenosa. Pag.379 * Urografía intravenosa. Pag.379 * Donativos a la Biblioteca de la Faculta de Medicina. Pag.380 * Sanidad de Medellín. Pag.381-389Sanidad de Medellin. Sanidad de Medellin anexo Bubon climatico; algunas anotaciones clinicas y terapeuticas Uribe Escobar, Gustavo p.335-358 El tratamiento de la sifilis Correa, Daniel p. 359-371 Fiebre perniciosa (observaciones clinicas) Arango Trujillo, Joaquin p.372-375 Evolucion del Ornithodorus Talaje Botero Jaramillo, Luis Eduardo p.376-377 Enfermedad de Nicolas Favre y reaccion de Frei Martinez Echeverri, Miguel p.378-379 Urografia intravenosa Echeverri Duque, Martiniano p.379 Sanidad de Medellin Sanidad de Medellin p.381-38