| Chiral heterocyclic skeletons have been widely found to exist in many drug molecules and natural products,which showed broad pharmacological activities such as antibacterial,anti-tumor,anti-malaria.Transition metal catalyzed asymmetric carbon-heteroatom coupling reaction is an important method for the synthesis of such skeletons.However,great disadvantages exist in such methods,such as the requirement of preinstalled halogen in the substrate,the strict anhydrous and oxygen-free reaction condition,environmental pollution,et al.Thus,it is highly desirable to develop novel methods as alternatives to transition metal catalysis.In this thesis,we have developed an asymmetric aryl C-O bond formation reaction and an asymmetric C-N bond formation reaction through chiral phase transfer catalysis or chiral hypervalent iodine catalysis,respectively.Based on these methods,two types of chiral heterocyclic compounds were synthesized.1.Chiral phase transfer-catalyzed asymmetric S_NAr reaction for the construction of diarylether heptanoids.A chiral phase-transfer-catalyzed intramolecular S_NAr cyclization was developed for enatioselective formation of diarylether cyclophane skeletons and applied as the key step for the asymmetric synthesis of natural products(-)-Pterocarine and(-)-Galeon.The reaction is performed under very mild conditions.Good enantioselectivity and high yields were obtained in this research.2.Chiral aryliodine-catalyzed asymmetric aryl C-N coupling reaction for the construction of chiral nitrogen heterocyclic compounds.An asymmetric oxidative C-N bond-forming reaction is developed with chiral diiodospirobiindane derivatives as the catalysts and mCPBA as a terminal oxidant.The protocol is based on an asymmetric desymmetrization strategy.The corresponding products were obtained in good yields and with moderate to good enantioselectivities.The reaction mechanism is proposed based on the experimental data and the literature reports. |
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