Waste-Minimized Cyanosilylation of Carbonyls Using Fluoride on Polymeric Ionic Tags in Batch and under Continuous Flow Conditions

Herein, we report the development of a tailor-made fluoride-based heterogeneous catalyst, POLITAG-F, for the waste-minimized continuous production of cyanohydrin silyl ethers. The careful designing of the polymeric support and the choice of fluoride ion as the anionic species resulted in the improvement of catalytic efficiency and allowed the effective conversion of different carbonyls (aldehydes, ketones, and unsaturated ketones). The POLITAG-F catalyst, employed under flow conditions, led to the conversion of large amounts (over 100 mmol) of the substrate with a productivity of 0.1 mmol min–1. In addition, flow conditions allowed to minimize the waste production reaching an associated E-factor value of 0.04. An exhaustive evaluation of the environmental impact of our protocol has been reported by considering several green metrics (process mass intensity, atom economy, and reaction mass efficiency) and also the benign index and the safety hazard index of the process.