Applications Of Ultrasound Irradiation In Some Condensations

The applications of ultrasound in organic synthesis in recent years have been reviewed. Studies on the cyclocondensation have been carried out under ultrasound irradiation. This thesis consists of five chapters: Chapter 1: Ultrasound irradiation has increasingly been used in organic synthesis in recent years. Compared with traditional methods, this method is more convenient and easier to be controlled. A large number of organic reactions can be carried out in higher yields, shorter reaction times and milder conditions under ultrasound irradiation. The applications of ultrasound in organic synthesis in recent years have been reviewed in this paper. Chapter 2: Knoevengel condensation of malononitrile with aromatic aldehydes in the absence of catalysts results arylmethylenemalononitriles in 70-98% yields in anhydrous ethanol under ultrasound irradiation. Chapter 3: 1,1-Disubstituted-2,6-diarylcyclohexane-4-ones have been synthesized via double Michael addition of 1,5-diaryl-1,4-pentadien-3-one with various active methylene compounds such as dimethyl malonate, diethyl malonate, methyl cyanoacetate and ethyl cyanoacetate catalyzed by KF/basic alumina under ultrasound irradiation to give good yields within a short time. Chapter 4: Synthesis of 2-amino-4-aryl-3-carbalkoxy-7,7-dimethyl-5-oxo-5,6,7,8-tertra-hydro-benzo-[b]-pyran derivatives was carried out in 84-98% yields by one pot condensation of aromatic aldehydes with cyanoacetic esters and 5,5-dimethyl-1,3-cyclohexanedione catalyzed by KF/basic Al2O3 at room temperature under ultrasound irradiation. Chapter 5: In the presence of trisodium phosphate, cross-aldol reactions of reactive aldehydes with substituted acetophenone in CH3OH-water mixed solvent afford β-hydroxyl ketones in good to excellent yields under ultrasound irradiation.