Silica-HClO4 catalyzed ortho-amidoalkylation of phenolsSilica-HClO4 catalyzed ortho-amidoalkylation of phenols
SyntheticPage 713
Published Feb 02, 2014
Preparation of Silica-HClO4 catalyst: Perchloric acid (1.25 g, as a 70% aqueous solution) was added to the suspension of silica gel (23.75 g, mesh 230–400) in Et2O. The mixture was concentrated and the residue was heated at 100 °C for 72 h under vacuum to afford Silica-HClO4 as a free flowing powder. http://dx.doi.org/10.1039/B304178F
Procedure for synthesis of titled product: To the solution of ortho-cresol (300 mg, 1 mmol) in acetonitrile (25 mL) were added formaldehyde (0.25 mL, 3 mmol), caprolactam (471 mg, 1.5 mmol) and 50% w/w silica-HClO4 (150 mg). The mixture was then heated to reflux at 80 °C for 6 h. Completion of the reaction was monitored by TLC (by observing the disappearance of ortho-cresol on TLC). Reaction mixture was then cooled to room temperature and filtered through filter paper. The filtrate was concentrated on a rotary evaporator to give the crude product as a yellow oil. Purification by silica gel (mesh 100-200) column chromatography using EtOAc: Hexane - 1:1 as eluent gave product as white solid (84% yield).