The silver salt of 12-tungstophosphoric acid: A mild and selective catalyst for the synthesis of β-ketoesters via C–H insertion

Aldehydes undergo smooth coupling with ethyl diazoacetate in the presence of 5 mol% silver substituted tungstophosphoric acid (AgTPA) under mild conditions to furnish β-ketoesters in high yields and with high selectivity via C–H insertion. This method is very useful for the preparation of β-ketoesters from both electron-rich as well as electron-deficient aromatic aldehydes. The catalyst can be recycled and reused for three to five subsequent runs with a gradual decrease of activity.