β‐Cyclodextrin‐Monosulphonic Acid Catalyzed Efficient Synthesis of 1‐Amidoalkyl‐2‐naphthols

Abstract

AbstractAn efficient and rapid approach for the synthesis of 1‐amidoalkyl‐2‐naphthols catalyzed by β‐cyclodextrin‐monosulphonic acid under solvent‐free conditions is described. The catalyst can be prepared easily from readily available β‐cyclodextrin in a single step procedure and is characterized by ESI‐Mass (Electrospray Ionization‐Mass), elemental analysis and TGA (Thermogravimetric analysis). Totally 29 compounds are prepared from various aromatic aldehydes, amides and 2‐naphthol using this β‐cyclodextrin‐monosulphonic acid indicating the broad substrate scope of this method. The key benefits of this atom economical method comprise a simple and a single step preparation of the catalyst, shorter reaction time (6‐20 minutes), good to excellent yields (72‐96%), mild reaction conditions, wide range of functional group tolerance, absence of any tedious workup or purification, it avoids hazardous reagents/solvents and reusable upto five runs. A suitable reaction mechanism which is supported by energy minimization studies, is proposed.