Sulfamic Acid: A Recyclable Catalyst for the Synthesis of Triaryl‐ and Triheteroarylmethanes from Aldehydes and Activated Arenes

A practical route to triarylmethanes: Sulfamic acid was found to efficiently catalyze Friedel-Crafts alkylations of 2-methyl furan or 1, 2, 4-trimethoxybenzene with a variety of simple or functionalized aldehydes to provide di-or triarylmethanes in high yields. The reaction tolerated variety of substitutions and functional groups under "open-flask", mild and solvent-free conditions. Moreover, the Sulfamic acid can be conveniently recycled is especially noteworthy.