Researchers in Prof. Miquel A. Pericàs lab published the first asymmetric Robinson annulation in continuous flow, which allows the synthesis of utmost important building blocks in organic synthesis, such as the Wieland–Miescher ketone or the Hajos–Parrish ketone. For instance, the Wieland–Miescher ketone has been used as the precursor for more than 50 natural products like steroids, antibiotics, and world-famous anticancer drug paclitaxel (Taxol®).
This paper represents the first example of a Robinson annulation reaction carried out in continuous flow. Pericàs and his collaborators developed a supported chiral catalyst that shows very high activity and enantioselectivity. The reactions can be carried out at mild temperatures (under 60ºC) and most of them in very short periods of time (1-2 hours).
The catalyst developed can be used non-stop during 24h to prepare some of the products in a multigram scale, with turn over numbers of as much as 117. The catalyst are sustainable because they can be cleaned and recycled without affecting their efficiency.
A Highly Active Polymer-Supported Catalyst for Asymmetric Robinson Annulations in Continuous Flow
S. Cañellas, C. Ayats, A.H. Henseler, M.A. Pericàs.
ACS Catal., 2017, DOI: 10.1021/acscatal.6b03286