Study On Organic Chemical Reactions Involving Aldehydes In Ethyl Lactate

In recent years,with the deterioration of the natural environment,all levels of society have become more and more concerned about environmental issues,especially in the field of traditional organic chemistry that polluted the environment.Therefore,there was a rising demand for more environmentally friendly protocols in the pharmaceutical and synthetic organic chemistry.However,most traditional organic solvents were volatile,toxic and unsafe,and in some specific cases,solvents were critical in the synthesis process(high temperature reaction conditions and solvent-induced product selectivity,etc.).Thence,experimenters must choose the green solvent that has less impact on the environment and health.Ethyl lactate(EL)has the advantages of low toxicity,low volatilization,high stability,good biodegradability,low price and good solubility to water and organic matter.Consequently,ethyl lactate was widely concerned by chemists and was called a“green solvent” with great development value and application prospects.First,organic reactions based on the use of ethyl lactate as the reaction medium have been reviewed.Combined with the advantages of catalyst-free reaction and one-pot multi-component reaction,theorganic reactions involving the green solvent ethyl lactate were studied,and some important heterocyclic compounds were synthesized.A highly efficient and environmentally friendly approach has been reported for the synthesis of bis(indolyl)methanes and 3,3-bis(indolyl)oxindoles by reacting of indoles with aldehydes or isatins in water-ethyl lactate under ultrasound irradiation.This protocol presents the benefits of catalyst-free,operational simplicity,short reaction time,high product yield,broad substrate scope and applicability for large-scale synthesis.In Chapter 3,a highly efficient and environmentally friendly process for the synthesis of ?-aminophosphonates has been devised,through a one-pot three-component condensation of various aldehydes,amines and triethyl phosphite inwater-ethyl lactate under ultrasonic irradiation conditions at room temperature.The expected products were obtained in high yield without the need for any additional catalyst.In Chapter 4,a highly efficient,economical,environmentally friendly and low-toxic method was investigatedfor the synthesis of quinoline derivatives.Quinoline derivatives were obtained via one pot,four-component reaction of aromatic aldehydes,malononitrile,ammonium acetate,5,5-dimethylcyclohexane-1,3-dione or2-hydroxy-1,4-naphthoquinone in ethyl lactate/water under visible light irradiation at room temperature.This method improved on existing techniques,avoided the use of any other catalysts and thermal energy,and gave the product in high yield.