Application Of Chiral Zwitterionic Quaternaty Ammoniums Catalysts In Michael Addition And Synthesis Of 4-substituted 3-(2-hydroxyphenyl)-quinolines

Chiral catalysts play a key role in the asymmetric catalytic reactions.Thus the design of novel and efficient chiral catalysts is crucial in the field of catalytic asymmetric synthesis.Herein,the novel zwitterionic quaternary ammonium salts bearing nitrogen anion were synthesized derived from chiral 1,2-diaminocyclohexane and 1,2-diphenylethylenediamine.The zwitterionic quaternary ammonium salts were used as the chiral catalyst to explore Michael addition of malononitrile to enones,and high enantioselectivities were achieved.In addition,a synthesis of 4-substituted 3-(2-hydroxyphenyl)-quinolines through iron(?)chloride promoted reaction of seven-numbered cyclic imine dibenzo[b,f][1,4]oxazepines with terminal alkynes was also presented.1.Synthesis of novel zwitterionic chiral catalysts and the application in enantioselective Michael addition of malononitrile to enonesEight novel zwitterionic chiral quaternary ammonium salts catalysts derived from c2-symetry chiral 1,2-diaminocyclohexane and 1,2-diphenylethylenediamine were synthesized via two steps(sulfoamidate with pentafluorobenzenesulfonyl chloride and alkylation of tertiary amines),with the moderate to good yields.Their structures were fully characterized by HRMS,NMR and IR.Subsequently,these obtained zwitterionic chiral quaternary ammonium salts were used as catalyst to test Michael addition of malononitrile to enones.After screening catalysts,we found the anthracylated ammonium salt derived from chiral 1,2-diphenylethylenediamine was the best catalyst.For varieties of enones,the Michael addition of malononitrile proceeded smoothly with 36-99%yields and up to 96%ee under the optimized conditions.2.Synthesis of 4-substituted 3-(2-hydroxyphenyl)-quinolines through iron(?)chloride promoted reaction of cyclic imines with alkynes4-Substituted 3-(2-hydroxyphenyl)-quinolines were synthesized through FeCl3-promoted reaction of cyclic imine dibenzo[b,f][1,4]oxazepines with alkynes.A variety of substituted cyclic imines and terminal alkynes(arylacetylenes,conjugated enynes,and 1,3-diynes)were used for this reaction type resulting in the formation of the corresponding products in 33-88%yields.The reaction represents an efficient method for the synthesis of novel quinoline derivatives.