Studies On Formation Of C-C/C-X Bond Based On C-H Bond Functionalization

1.Construction of C-X(X=Cl,Br,I)bonds via C-H bond functionalizationAs one of the most important units,organic halides are common stuctures in natural products,drugs,bioactive compounds and functional materials,which are bluiding blocks in organic synthesis.Although much progress has been achieved in this field,it is still desirable to develop new methods in more atomic-economic and environmental ways.Our group have developed a Pd(II)-catalyzed halogenation reaction of ortho-C-H bonds of2-pyridyl sulfoxides.This reaction proceeded smoothly,tolerated a variety of functional groups,showed good regio-selectivity,and afforded an efficient method to synthesize S(O)-containing compounds.After that,our group developed a new strategy for remote C-H bond halogenation of8-aminoquinolines(C5 position)under transition-metal-free conditions.This method presented features good functional-group tolerance and potential for large-scale reactions.The products has been demonstrated by their transformation into other useful skeletons.2.Construction of C-C bond via[Cp*Co(III)]-catalyzedC-H bonds of 1,4-addition reaction Because of its high electrophilicity,maleimide is the privileged compound in 1,4-addition reactions,whose addition products with a succinimide structure can be easily reduced to a pyrrolidine structure.So maleimides were chosen as the Michael acceptors in the1,4-addition reactions of[Cp*Co(III)]-catalyzed C-H bond.Firstly,cobalt-catalyzed arene sp2 C–H bond conjugation addition to maleimide was reported.The reaction showed great tolerance to different functional groups,and various succinimide derivativeswere efficiently produced.This protocol exhibited specific reactivity with only producing a mono-C–H bond addition product and no external base was needed,which suggested a unique reactivity of this Co-based catalytic system.Thereafter,Co(III)-catalyzed sp~3 C–H bond 1,4-addition reactions was explored.The protocol for the alkylation reactions of8-methylquinolines with maleimides was efficient and atom-economic.Moreover the reaction also exhibited exceptional reactivity,satisfactory yields,excellent chemo-and regioselectivity,and tolerates a variety of functional groups.As a result,a simple green preparation for asymmetric succinimide and pyrrole rings was provided in both of the C-C bonds construction reactions.