2,4,6-Triarylpyridines (Kröhnke pyridines) are structurally related to symmetrical triaryl-thiopyrylium, -selenopyrylium and -telluropyrylium photosensitizers, which have been recommended for photodynamic cell-specific cancer therapy [1]. These compounds have already been synthesized through the reaction of N-phenacylpyridinium salts with α,β-unsaturated ketones in the presence of ammonium acetate [2]. More recently, several new improved methods and procedures for preparation of 2,4,6-triarylpyridines have been reported such as reaction of α-ketoketene dithioacetals with methyl ketones in the presence of NH4OAc, reaction of N-phosphinylethanimines with aldehydes, solvent-free reaction between acetophenones, benzaldehydes, and NH4OAc in the presence of various catalysts such as Preyssler type heteropolyacid, HClO4-SiO2, and I2, and the one-pot reaction of acetophenones, benzaldehydes and NH4OAc without catalyst under microwave irradiation [3-6]. To the best of our knowledge, there are no examples of the use of carbon-based solid acid as catalyst for the synthesis of 2,4,6-triarylpyridines. Thus, herein we would like to report an efficient procedure for the preparation of 2,4,6- triarylpyridines through a one-pot three-component reaction including acetophenones, aryl aldehydes, and NH4OAc in the presence of carbon-based solid acid as catalyst. The catalyst can be reused after a simple work-up. Other advantages of these protocols are high yields, relatively short reaction times and easy work-up.

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