Trialkylamine Controlled Phenol–Formaldehyde Reaction over Clay Catalysts: Selective and Environmentally Benign Synthesis of Salicylic Aldehydes

Substituted salicylic aldehydes 6 are synthesised in good yields and excellent selectivities by reaction of phenols 1 with formaldehyde 2 over montmorillonite KSF–Et3N as a heterogeneous and reusable catalyst.