A Simple and Straightforward Synthesis of Cinnamic acids and Ylidene Malononitriles via Knoevenagel Condensation Employing DABCO as Catalyst

The α,β-unsaturated compounds such as cinnamic acid and ylidene malanonitriles are important reagents in organic synthesis both as intermediates and final products. They have been used to prepare compounds of biological relevance such as terahydromyricoid [1] or the antibacterial reutericyclin [2]. They are also present in some natural products, such as the juice secreted by queen honey bee [3]. They are synthesized on a commercial scale owing to their applications in food industry, polymer industry, perfume industry and technical applications. The ylidene malononitriles (α,β-unsaturated nitriles) are versatile tools for production of a variety of biologically active new heterocycles [4]. Knoevenagel condensation (Doebner modification) is one of the leading methods for the synthesis of α,β-unsaturated carboxylic acids and nitriles from aromatic aldehydes possessing active methylene group. The classic Knoevenagel-Doebner reaction has been carried out using high amounts of basic solvents like pyridine, NaOH, Et3N, CH3NH2 and KOH. The excess amounts of these solvents damage the chemicals employed in the reaction due to their volatile nature and they are also environmentally hazardous [5]. A range of various catalysts have been used for this reaction such as ammonia, primary and secondary amines, Lewis acids, surfactants and ionic liquids [6]. In case of ultrasound [7] and microwave [8] A Simple and Straightforward Synthesis of Cinnamic acids and Ylidene Malononitriles via Knoevenagel Condensation Employing DABCO as Catalyst