Highly enantioselective synthesis of both tetrahydroquinoxalines and dihydroquinoxalinonesviaRh–thiourea catalyzed asymmetric hydrogenation

Abstract

Chiral tetrahydroquinoxalines and hydroquinoxalinones represent the core structure of many bioactive molecules. Herein, a simple and efficient Rh-thiourea-catalyzed asymmetric hydrogenation for enantiopure tetrahydroquinoxalines and dihydroquinoxalinones was developed under 1 MPa...

Iridium-catalyzed asymmetric, complete hydrogenation of pyrimidinium salts under batch and flow

“…Recently, flow chemistry gained significant attention due to its benefits, like short residence time, high surface area-to-volume ratio, excellent reproducibility and easy scale-up. 33–36 Importantly, hydrogen gas is highly flammable and can easily form explosive mixtures with oxygen in the air. In a continuous flow system, hydrogen gas can be handled and controlled more safely, reducing potential hazards.…”

Sustainable synthesis of long-acting local anesthetics ropivacaine and levobupivacaine under batch and continuous flow via asymmetric hydrogenation

“…In recent times, flow chemistry has garnered considerable attention owing to its advantages, such as short residence times, a high surface area-to-volume ratio, excellent reproducibility, and ease of scale-up. 20,28–32 Importantly, hydrogen gas is highly flammable and can easily form explosive mixtures with oxygen in the air. Utilizing a continuous flow system allows for safer handling and control of hydrogen gas, thus mitigating potential hazards.…”

Iridium-catalyzed asymmetric hydrogenation of 5-hydroxypicolinate pyridinium salts under batch and flow: stereodefined access to cis-configurated hydroxypiperidine esters

“…In a continuous flow system, however, hydrogen gas can be handled and controlled more safely, thereby reducing potential hazards. 66,67 To enhance the sustainability of our developed approach, we selected methyl-5-hydroxypiperidine-2-carboxylate 1m as a representative substrate for investigation in an asymmetric hydrogenation process within a continuous flow system. Initially, the reaction was conducted in a fixed bed reactor containing 10% NaHCO 3 .…”