Transition Metal-Catalyzed C-H Functionalization for Sustainable Syntheses of Alkenes and Heterocycles

by Wenbo Ma
Doctoral thesis
Date of Examination:2015-05-04
Date of issue:2015-05-13
Advisor:Prof. Dr. Lutz Ackermann
Referee:Prof. Dr. Lutz Ackermann
Referee:Prof. Dr. Dietmar Stalke
Persistent Address: http://dx.doi.org/10.53846/goediss-5070

 

 

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Description:The rapid progress of C–H functionalization chemistry over the last decade has provided numerous efficient protocols for forming new chemical bonds. Especially, the ruthenium(II)-catalyzed direct C–H alkenylations and annulations have been proven viable with a broad substrates scope and excellent chemo-, regio-, and site-selectivity. These carboxylate-assisted ruthenium(II)-catalyzed C–H functionalizations were even allowed in an aerobic fashion with Cu(OAc)2•H2O under an atmosphere of ambient air. Yet, less expensive first-row transition metal complexes such as cobalt salts were also identified as versatile catalysts for step-economical chelation-assisted direct C−H alkenylations in user-friendly solvent. This Co(OAc)2 catalyst can enable the transformation smoothly with a widely range functional groups tolerance, to furnish the isoindolin-1-ones in high yields. Finally, we developed silver-mediated alkyne annulations by C–H/P–H functionalizations. This transformation proceeded with excellent chemo- and site-selectivities in the presence of silver acetate as the terminal oxidant, thereby furnishing substituted phosphindole with broad scope. The radical mechanism of the C–H/C–P functionalization was unraveled though detailed mechanistic studies.

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Abstract

English

The rapid progress of C–H functionalization chemistry over the last decade has provided numerous efficient protocols for forming new chemical bonds. Especially, the ruthenium(II)-catalyzed direct C–H alkenylations and annulations have been proven viable with a broad substrates scope and excellent chemo-, regio-, and site-selectivity. These carboxylate-assisted ruthenium(II)-catalyzed C–H functionalizations were even allowed in an aerobic fashion with Cu(OAc)2•H2O under an atmosphere of ambient air. Yet, less expensive first-row transition metal complexes such as cobalt salts were also identified as versatile catalysts for step-economical chelation-assisted direct C−H alkenylations in user-friendly solvent. This Co(OAc)2 catalyst can enable the transformation smoothly with a widely range functional groups tolerance, to furnish the isoindolin-1-ones in high yields. In the last project, we developed silver-mediated alkyne annulations by C–H/P–H functionalizations. This transformation proceeded with excellent chemo- and site-selectivities in the presence of silver acetate as the terminal oxidant, thereby furnishing substituted phosphindole with broad scope. The radical mechanism of the C–H/C–P functionalization was unraveled though detailed mechanistic studies.
Keywords: Transition Metal-Catalysis, Directing Group, Alkenylation, Annulation
 
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