Tin Pyrophosphate (SnP2O7): As a Novel Heterogeneous and Highly Efficient Catalyst for the One Pot-Three Component Synthesis of Tetrahydrobenzo[b]Pyran and Dihydropyran[c]Chromene Derivatives

The tin pyrophosphate (SnP2O7) was synthesized from the modification of mono-ammonium phosphate (MAP) by tin chloride (SnCl2). This solid was used as a heterogeneous catalyst for the one-pot multicomponent synthesis of tetrahydrobenzo[b]pyran and dihydropyrano[3,2-c]chromenes derivatives under green reaction conditions. This synthetic protocol offers several advantages such as short reaction times (8-15 min), high product yields (85-97%), easy work‐up procedure, and easy catalyst separation from the reaction mixture. In addition, SnP2O7 can be recycled for up to five cycles without a significant loss of catalytic reactivity. The XRD and IR spectra confirm the stability and heterogeneity of SnP2O7 in the reaction medium even after its reuse.