Here we report a sustainable protocol for the cyanosilylation of carbonyl compounds 1a-g and 3a-m using trimethylsilyl cyanide and triphenylphosphine supported on polystyrene as catalyst under solvent-free conditions. It has been shown that a small amount of the catalyst allows the chemoselective 1,2-addition of trimethylsilyl cyanide to α,β-unsaturated ketones 1a-g (5 mol%) and to satured ketones 3a-m (2 mol%). The preparation of cyanohydrin trimethylsilyl ethers 2a-g and 4a-m has been accomplished in good yields (72-99%) and very low E-Factor values (5-10). Finally, efficiency has been further improved by setting two different flow procedures that have allowed to perform the representative preparation of ketone 4a on large scale and with the E-Factor of 0.16 or 0.47 consisting in a reduction of 90 or 72% of waste compared to our batch conditions.
Efficient synthesis of cyanohydrin trimethylsilyl ethers via 1,2-chemoselective cyanosilylation of carbonyls
STRAPPAVECCIA, GIACOMO;LANARI, DANIELA;PIZZO, Ferdinando;ROSATI, Ornelio;CURINI, Massimo;VACCARO, Luigi
2013
Abstract
Here we report a sustainable protocol for the cyanosilylation of carbonyl compounds 1a-g and 3a-m using trimethylsilyl cyanide and triphenylphosphine supported on polystyrene as catalyst under solvent-free conditions. It has been shown that a small amount of the catalyst allows the chemoselective 1,2-addition of trimethylsilyl cyanide to α,β-unsaturated ketones 1a-g (5 mol%) and to satured ketones 3a-m (2 mol%). The preparation of cyanohydrin trimethylsilyl ethers 2a-g and 4a-m has been accomplished in good yields (72-99%) and very low E-Factor values (5-10). Finally, efficiency has been further improved by setting two different flow procedures that have allowed to perform the representative preparation of ketone 4a on large scale and with the E-Factor of 0.16 or 0.47 consisting in a reduction of 90 or 72% of waste compared to our batch conditions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.