A general and efficient one-pot synthesis of spiro[2-amino-4H-pyrans] via tandem multi-component reactions catalyzed by Dabco-based ionic liquids

A simple and highly efficient procedure for general synthesis of densely functionalized spiro[4H-pyran-3,3′-oxindole] derivatives from a wide range of carbonyl compounds, active methylenes and various kinds of enols catalyzed by Dabco-base ionic liquids has been successfully developed. All the reactions undergo an tandem Knoevenagel-Michael-cyclization process and afford the desired products in excellent yields within short times. The ionic liquid catalyst is inexpensive and which could be easily recycled and reused five times without significant loss of catalytic activity.