Efficient synthesis of spironaphthopyrano [2,3-d]pyrimidine-5,3'-indolines under solvent-free conditions catalyzed by SBA-Pr-SO3H as a nanoporous acid catalyst.

A green, simple one-pot synthesis of spironaphthopyrano[2,3-d]pyrimidine-5,3'-indoline derivatives by a three-component reaction of isatins, 2-naphthol, and barbituric acids under solvent-free conditions in the presence of SBA-Pr-SO(3)H has been accomplished. Sulfonic acid functionalized SBA-15 (SBA-Pr-SO(3)H) as a heterogeneous nanoporous solid acid catalyst was found to be an efficient and recyclable acid catalyst in this synthesis.