Sequential photothermal flow chemistry delivers high yields of bicyclic lactams
Researchers at the University of Bristol have successfully prepared bicyclic lactams in high yield and excellent purity, using a photochemical [2+2] cycloaddition followed by a thermal electrocyclic cascade
21 Sept 2021
By moving the photochemistry, performed using a PhotoSyn™ LED photoreactor, from ultraviolet (UV) to visible, the Bristol researchers were able to make their [2+2] ring closure much more energy efficient. Integrating this with a FlowSyn™ Continuous Flow Reactor, they were also able to apply automated high-temperature flow chemistry to the thermal cascade step, facilitating safe and reliable scale-up with short reaction times.
Using this experimental setup - the researchers were able to demonstrate a unique example of a photothermal daisy-chained process combining a visible-light-mediated photochemical initiation and a thermal cascade reaction as a fully continuous process yielding 20 grams/hour. This process was facilitated by the ability to employ acetonitrile as solvent at high temperature under pressurized conditions and the precise control of residence time and temperature in the flow reactor which enabled the isolation of a reactive diene intermediate on a scale and yield not achievable under batch conditions.
The Uniqsis FlowSyn™ is a fully integrated continuous flow reactor with everything you need to start doing flow chemistry including reaction optimization, synthesis, and scale-up. To provide maximum flexibility, a wide range of mixer and reactor options are available as well as additional modules for performing multiple experiments, or sub-ambient chemistry. Fully compatible with the FlowSyn™, the PhotoSyn™ photoreactor lamp module is designed to provide scientists with a high-power LED light source for continuous flow applications. Available with a selection of different LED arrays the unit can provide outputs up to 700W from the dedicated programmable power supply.
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FlowSyn Continuous Flow Reactor
Uniqsis LtdFlowSyn - Making Flow Chemistry Simple FlowSyn is a fully integrated continuous flow reactor with everything you need to start doing flow chemistry including reaction optimization, synthesis and scale up. To provide maximum flexibility, a wide range of mixer and reactor options are available as well as additional modules for performing multiple experiments, or sub-ambient chemistry. • Ability to perform continuous flow chemistry under microwave-like conditions (up to 260oC). • Perform sub-ambient continuous flow chemistry using the 'Cold Coil'. • Run up to 10 automated sequential experiments with the 'Automated Experiment Package'.A pair of high pressure pumps are used to deliver reagent solutions from either stock bottles or sample injection loops through a 'T'-mixer into the electrically heated flow reactors. Reactions can be heated to 260?C and 150?C in the coil and column reactor modules respectively. Back pressure regulators of up to 1000 psi are used to pressurise the system and thus perform superheating of solvents, allowing the chemist to access'microwave like' conditions with no limitation on scale. FlowSyn is very easy to use with a high resolution user interface. The user is guided through the process for setting up a flow chemistry reaction by inputting parameters for reagent volumes, temperatures and reaction times. The user can choose to collect all of the reaction plug, or only the 'steady state' part. FlowSyn will then equilibrate and run the reaction, and finally flush the system through with solvent. Throughout FlowSyn will monitor the pressure of the system, and shut down if a problem occurs allowing FlowSyn to be safely run unattended.