Studies On The Cascade Synthesis Of 4-chloroquinoline

4-chloroquinoline has been playing an important role in organic synthesis.Because of the special structure of benzopyridine,4-chloroquinoline has been widely used in pharmaceutical research and development,organic materials,battery materials,luminescent materials,and other fields.Since the discovery of quinoline structure,many methods for the synthesis of 4-chloroquinoline have been continuously found,but the mainstream synthesis method is still to use quinoline-4-one as the precursor to react with some chlorinated reagents（such as POCl3,PCl5,SOCl2,Apple-like reagents,etc.）to prepare 4-chloroquinoline.However,these chlorinated reagents are toxic and harmful,polluting the environment,difficult to recycle,difficult to post-processing,producing a large number of phosphoric acid by-products,and other shortcomings.In recent years,with the development of science and technology,new methods for the synthesis of 4-chloroquinoline have emerged endlessly,such as heterogeneous catalysis and other methods have also been reported,but these methods still have many problems that have not been solved,such as functional group compatibility is not strong,the reaction steps are cumbersome,the reaction time is too long,the reaction precursor is difficult to prepare.In this paper,4-chloroquinoline compounds were prepared from 2-alkoxy carbonyl-3-arylamino-3-alkylthio acrylate via one-pot cyclization/chlorination under the action of triphosgene.The following reaction process was obtained through a series of control experiments.Firstly,2-alkoxy carbonyl-3-arylamino-3-alkylthio acrylate was cyclized under heating conditions and the methoxy group was removed to obtain the corresponding 4-quinolone compounds.Then,4-quinolone compounds were chlorinated under the chlorination of triphosgene to obtain the products.Compared with the previous methods,the method reported in this paper has the following advantages: this method uses a novel and environmentally friendly chlorinated reagent-triphosgene,which is safer and more controllable than the traditional chlorinated reagent-triphosgene;the reaction time is greatly shortened;the reaction process is simple and less dangerous;the functional group compatibility is strong,and the yield of the target product is high.