Photodecarboxylations in an Advanced Meso‐Scale Continuous‐Flow Photoreactor

Abstract

Selected photodecarboxylations of phthalimides were realized under continuousflow conditions using an advanced meso-scale photoreactor. The improved efficiency, yields, and productivities of these photochemical reactions highlight the benefits of using flow as opposed to conventional batch operation modes. Flow chemistry furthermore allows for an easy combination of multiple reaction steps in series. This is demonstrated by the successful synthesis of a pharmaceutical target molecule through a tandem photochemical-thermal procedure carried out in uninterrupted flow.

Continuous Flow Photochemical and Thermal Multi-Step Synthesis of Bioactive 3-Arylmethylene-2,3-Dihydro-1H-Isoindolin-1-Ones

“…This is mainly caused by a reduction of isolation and purification steps. The developed reaction protocols may be transferred to more advanced and custom-designed continuous flow tandem reactors such as the Vapourtec UV-150 module [8,34]. The process furthermore demonstrates the synthesis potential of arylacetic acids [35] as well as photodecarboxylations [36][37][38].…”

“…The syntheses protocols involved utilize conventional step-by-step batch procedures. Examples of photodecarboxylations involving phthalimides in circulating or continuous-flow reactors have also been realized [7,8].…”

“…The syntheses protocols involved utilize conventional step-by-step batch procedures. Examples of photodecarboxylations involving phthalimides in circulating or continuousflow reactors have also been realized [7,8]. Flow chemistry allows for the continuous manufacturing of target compounds under controlled conditions [9,10].…”

Process Intensification – An Unbroken Trend in Chemical Engineering

“…Further process intensification can be achieved through continuous flow reactors . Furthermore, several recent publications illustrate the benefits of advanced reactor concepts, e.g., packed‐bed‐, pneumatic nebulizer‐, slug flow, annular flow, vortex or luminescent solar concentrator reactors .…”

Prospects for Flow Chemistry

“…Invited presentations discussed (1) photochemical transformations by T. Noël [4], S. Fuse [5], M. Oelgemöller [6], and A. Beeler [7]; (2) generation and safe usage of hazardous species by K. Hirose [8], C. O. Kappe [9,10], and T. Wirth [11]; (3) carbonylation reactions by I. Ryu [12]; (4) catalysis by N. Kumagai [13] and R. Souza [14]; (5) multistep synthetic transformations by T. Jamison [15,16] and A. Kulkarni [17]; (6) polymer construction by C. Serra [18]; and finally, (7) general advances in flow chemistry by M. Organ [19], D. Kim [20,21], and E. Kumacheva [22]. The popularity of these transformations is driven by the need to overcome the limitations of conventional batch reactions such as mixing, thermal control, safety metrics, and scale-up issues.…”