Keggin-type Bronsted dodecatungstophosphoric acid: a quasi homogenous and reusable catalyst system for liquid phase Beckmann rearrangement

A variety of ketoximes, prepared from corresponding ketones, undergo Beckmann rearrangement using H3PW12O40 (DTPA) in acetonitrile under reflux to yield N-substituted amides and lactams in good to excellent yields (72–96%). The present method provides an efficient, clean, eco-friendly, and simple synthesis. The catalyst is cheap, moisture tolerant, recoverable, and reusable without much loss of its activity.