Uniqsis reports how researchers at the University of Bristol have successfully prepared bicyclic lactams in high overall yield and excellent purity, under flow through conditions, using a photochemical [2+2] cycloaddition followed by a thermal electrocyclic cascade.
By moving the photochemistry, performed using a PhotoSyn LED photoreactor, from ultraviolet (UV) to visible, the researchers were able to make their [2+2] ring closure 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 set-up - the researchers were able to demonstrate an 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 an hour. The process was facilitated by the ability to employ acetonitrile as solvent at high temperature under pressurised 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 an integrated continuous flow reactor with everything you need to start doing flow chemistry including reaction optimisation, synthesis and scale up. A range of mixer and reactor options are available as well as additional modules.
