Carboncations are an important class of active intermediates in organic chemical reactions,and studying their formation and transformation is of great significance.Based on the previous research results,this thesis successfully applied the Re2O7/HFIP catalytic system into several reactions involving carboncations,solving the problems of need of strong corrosive acid catalysis,high reaction temperature,and large catalyst dosage in traditional reactions involving carboncations.(1)In this thesis,Re2O7 or HRe O4/HFIP catalytic system was applied into intermolecular hydroarylation of electron-deficient styrenes and different aromatics.By using this catalysis system,1,1-diarylalkane compounds can be obtained in high yield with low catalyst loading.The system was also suitable for gram-scale synthesis and showed good catalytic efficiency in the synthesis of a selective retinoic acid receptor(RAR)agonist.Based on the results of DFT calculations and deuterium labeling experiment,the possible mechanism of the reaction was proposed,in which the protonation of olefins might be the rate-determining step.This catalytic system exhibited high substrate tolerance,providing a mild and efficient method for construction of 1,1-diarylalkane derivatives.(2)Subsequently,Re2O7 or HRe O4/HFIP system was used to catalyze the intermolecular ring-opening arylation of electron-deficient phenyl cyclopropanes with different aromatics.By using this catalytic system,varied 1,1-diarylalkane compounds could be obtained in high yield under relatively mild conditions.Based on the results of deuterium labeling experiment,the ring-opening protonation of aryl cyclopropane might be the rate-determining step in the reaction process.The possible mechanism of the intermolecular ring-opening arylation of electron-deficient phenyl cyclopropane was proposed.This catalytic system breaks through the limitation of electron donor-acceptor type substrate and provides another alternative strategy for the efficient construction of1,1-diarylalkane skeleton compounds.(3)In addition,this thesis also confirmed the possibility of the application of Re2O7/HFIP-d1 system into the H-D exchange reaction of electron-rich aromatics.Through a series of conditions screening,it was finally determined that Re2O7/Ac OD system could replace Re2O7/HFIP-d1 system to catalyze the H-D exchange reaction of more electron-rich aromatics,and Re2O7/TFA-d1 catalytic system was used for the H-D exchange reaction of general electron-rich aromatics.Using this catalytic system,a series of highly deuterated(hetero)aromatics or polycyclic(hetero)aromatics at specific sites have been gained,including natural products or drugs.The catalytic system featured with mild conditions,convenient operation,low cost and high substrate tolerance,which provides an important means for the efficient synthesis of highly deuterated electron-rich aromatics and deuterium modification on drugs or bioactive compounds.In this thesis,exploration and research on several reactions involving carbocation has been carried out.Re2O7 or HRe O4/HFIP catalytic system was successfully applied into arylation reactions of electron-deficient styrenes or electron-deficient phenyl cyclopropane with aromatics,by which a variety of 1,1-diarylalkane derivatives were efficiently constructed;At the same time,the application potential of Re2O7/HFIP-d1 catalytic system was confirmed in the H-D exchange reaction of electron-rich aromatics,and it was determined that the Re2O7/Ac OD or TFA-d1 catalytic system could be used as an alternative system in the efficient synthesis of highly deuterated electron-rich aromatics.In short,these research works revealed the important role of HFIP in carbocation involved reaction,provided important theoretical and experimental support for other organic reactions involving carbocation and other acid-catalyzed H-D exchange reaction. |