Homogeneous and gas-liquid Catellani-type reaction enabled by continuous-flow chemistry

\u3cp\u3eA practical homogeneous and gas-liquid palladium-catalyzed Catellani-type reaction using a continuous-flow platform is described. The implementation of continuous-flow technology allowed the acceleration of the transformation and, for the first time, expansion of the chemical space to gaseous olefins (i.e., ethylene, propylene and 3,3,3-trifluoropropene), thus providing a safe and practical approach to sterically hindered ortho-disubstituted styrenes and vinyl arenes. The complete control over the stoichiometry of gaseous reagents through flow technology proved essential for directing the selectivity of the Catellani reaction to the desired products.\u3c/p\u3

Merger of visible-light photoredox catalysis and C–H activation for the room-temperature C-2 acylation of indoles in batch and flow

\u3cp\u3eA mild and versatile protocol for the C-H acylation of indoles via dual photoredox/transition-metal catalysis was established in batch and flow. The C-H bond functionalization occurred selectively at the C-2 position of N-pyrimidylindoles. This room-temperature protocol tolerated a wide range of functional groups and allowed for the synthesis of a diverse set of acylated indoles. Various aromatic as well as aliphatic aldehydes (both primary and secondary) reacted successfully. Interestingly, significant acceleration (20 to 2 h) and higher yields were obtained under micro flow conditions.\u3c/p\u3

Mild and selective base-free C–H arylation of heteroarenes:experiment and computation

A mild and selective C–H arylation strategy for indoles, benzofurans and benzothiophenes is described. The arylation method engages aryldiazonium salts as arylating reagents in equimolar amounts. The protocol is operationally simple, base free, moisture tolerant and air tolerant. It utilizes low palladium loadings (0.5 to 2.0 mol% Pd), short reaction times, green solvents (EtOAc/2-MeTHF or MeOH) and is carried out at room temperature, providing a broad substrate scope (47 examples) and excellent selectivity (C-2 arylation for indoles and benzofurans, C-3 arylation for benzothiophenes). Mechanistic experiments and DFT calculations support a Heck–Matsuda type coupling mechanism

Liquid phase oxidation chemistry in continuous-flow microreactors

Continuous-flow liquid phase oxidation chemistry in microreactors receives a lot of attention as the reactor provides enhanced heat and mass transfer characteristics, safe use of hazardous oxidants, high interfacial areas, and scale-up potential. In this review, an up-to-date overview of both technological and chemical aspects of liquid phase oxidation chemistry in continuous-flow microreactors is given. A description of mass and heat transfer phenomena is provided and fundamental principles are deduced which can be used to make a judicious choice for a suitable reactor. In addition, the safety aspects of continuous-flow technology are discussed. Next, oxidation chemistry in flow is discussed, including the use of oxygen, hydrogen peroxide, ozone and other oxidants in flow. Finally, the scale-up potential for continuous-flow reactors is describe