Study On Asymmetric Catalytic Reactions Based On Active Ortho-Quinone Methides

ortho-Quinone methides(o-QMs)are powerful synthetic intermediates,widely applied in organic synthesis,drug chemistry and material chemistry because of their highly reactivity.Generally,o-QMs have been mainly applied in conjugate additions,hetero Diels–Alder reactions,and 6?-electrocyclizations,etc.It was only recently that a range of catalytic,enantioselective processes have been successfully developed for o-QM chemistry including cinchona alkaloid-,chiral Br?nsted acid-and NHC-catalyzed reactions.In this dissertation,the synthesis methods of o-QMs active intermediates were summarized firstly,and the applications of o-QMs in asymmetric catalysis were also discussed.Based on these,two kinds of novel asymmetric reactions catalyzed by chiral bifunctional amine-squaramide were intensively studied on in situ generated o-QMs.An asymmetric Friedel-Crafts alkylation of 2-naphthol with in situ generated ortho-quinone methides(o-QMs)is designed and developed under the catalysis of chiral bifunctional amine-squaramide,and a series of chiral triarylmethane derivatives were obtained in good to high yields(up to 96% yield)with high enantioselectivities(up to 97% ee).This reaction not only enriches the application of ortho-quinone methides in asymmetric catalysis,but also provides a new method for the synthesis of chiral triarylmethane derivatives.This study also revealed that the use of oil-water biphase could realize the spatial separation of the TsH from the reaction mixture to effectively solve the problem of chiral amine-squaramide be protonated.In the following study,asymmetric sulfur-Michael addition reaction of thioacetic acid to in situ generated o-QMs was realized,leading to chiral sulfur-containing compounds in good to high yields(up to 96% yield)with high enantioselectivities(up to 96% ee).This reaction provides a new method for the construction of chiral benzyl C-S bond,and also revealed that the applicability of oil-water biphase in the asymmetric catalytic reaction involving in this kind of in situ generated ortho-quinone methides.In conclusion,two new methods for the synthesis of chiral triarylmethane derivatives and the construction of chiral benzyl C-S bond have been developed by using in situ generated o-QMs as reactive intermediates,catalyzed by chiral bifunctional amine-squaramide.Furthermore,based on the experimental results,the catalytic mode and the role of oil-water biphase were discussed and analyzed,which laid a certain foundation for the asymmetric catalysis involving in o-QMs.