Microwave-mediated solvent free Rap–Stoermer reaction for efficient synthesis of benzofurans

A Novel Synthesis of 2‐Ferrocenoyl‐Substituted Iodobenzofurans

“…Having a series of the iodo‐substituted salicylaldehydes 2a , 2b , 2c , 2d , 2e , 2f , 2g in hand, our attention was transferred to their Rap–Stoermer reaction with 1‐chloroacetylferrocene for building the 2‐ferrocenoylbenzofuran system. At this stage, we first investigated the reaction of 3‐iodo‐5‐methylsalicylaldehyde ( 2b ) with 1‐chloroacetylferrocene ( 3 ) under solvent‐free conditions or using 4‐dimethylaminopyridine as catalyst in water in accordance with literature methods. Although these procedures are very easy, eco‐friendly, and impressive, the purported approaches were ineffective in our hands, and the reaction did not proceed satisfactorily, giving poor yields of highly impure products.…”

Five‐Membered Heterocycles: Benzofuran and Related Systems

“…A microwave-mediated solvent-free Rap-Stoermer reaction has been reported for the synthesis of benzofurans from various salicylaldehydes and phenacyl halides (Scheme 7.48) [82]. Some of the advantages and highlights of this microwave protocol include, solvent-free clean reaction conditions and high yields of benzofurans obtained in short reaction times.…”

A facile and efficient addition reaction of nitrogen‐containing heterocyclic compounds with DMAD under neat conditions

“…Organic reactions in solventless system [1] and in aqueous media [2] are also very interesting from the viewpoint of green chemistry [3]. Some solvent‐free organic reactions were carried out incorporating the reactants in clays, zeolites, silica, alumina, or other matrices [4, 5]. Microwave, UV, or ultrasound irradiations have been used to bring about the reaction in dry media [6, 7].…”