Rhodium-catalyzed C-H Bond Activation Involving Alkynes/Olefins

In recent decades,transition metal-catalyzed the C-H bond activation reaction has developed rapidly and become one of the hot research fields in organic chemistry.Compared with the traditional cross coupling reaction,transition metal-catalyzed the C-H bond activation has some advantages,such as no substrate pre-activation step,avoiding the use of expensive ligands,reduceing the excess metal waste,simplifying the operation steps,and improving atom economy.In this thesis,the rhodium-catalyzed C-H activation/cyclization and C-H alkenylation reaction have been studied.The main research contents are as follows:1.A microwave assisted Rhodium-catalyzed C—H activation/cyclization of diaryl phosphoramides and alkynes has been developed,and a series of cyclic phosphoramides bearing five fluoro groups could be obtained in moderate to good yields.The optimized reaction conditions were established by examination of solvents,temperature,reaction time and bases.It is as follows:DCE（1,2-dichloroethane）as solvent,Na HCO₃as base,Ag₂CO₃as oxidant,and reaction temperature is 110^oC as well as reaction time is 15 minutes.Under the optimized reaction conditions,both diaryl phosphoramides and alkynes bearing various electron-donating groups and electron-withdrawing groups are suitable for this catalytic system,and the desired product was produced in highest yield of 93%.This reaction system was also feasible in a gram-scale reaction without significant decrease in the product yields,and a possible reaction mechanism was then proposed.Moreover,this methology was successfully applied to the synthesis of the novel diamine with the core of fluorine-containing substituted cyclic phosphoramide.2.A new method for highly efficient synthesis of terminal alkenylindoles through Rh（III）-catalyzed direct C-H alkenylation of 2,3-unsubstitued indoles employing easily accessible alkenyl borates as the vinylating reagent had been developed.The optimized reaction conditions were established by examination of solvents,temperature and oxidants.The present method features wide substrate scope,good functional group compatibility.A large number of substituted terminal alkenylindoles containing electron-donating groups,electron-withdrawing groups or halogens could be obtained under the optimized reaction conditions,and the highest yield of product is 89%.And then,the competition experiment between differently substituted indoles and KIE studies.A k _H/k _Dvalue of 1.0 was obtained from ¹H NMR analysis,and it suggested that the C-H bond cleavage was not involved in the rate-determining step.We were pleased to find that the reaction could be performed on a gram scale（6.0mmol）under the optimized conditions without a significant decrease in the product yield.Finally,the utility of this synthetic methodology is demonstrated in the synthesis ofγ-carboline.The model product could be transferred intoγ-carboline through three-step reaction in good yields.It provides an effective synthetic method for the preparation of pharmaceutical and pesticide intermediates based on carbolines.