Iron-catalyzed α-C–H functionalization of π-bonds: cross-dehydrogenative coupling and mechanistic insights

Abstract

The deprotonation of propargylic C–H bonds for subsequent functionalization typically requires stoichiometric metal alkyl or amide reagents. In addition to the undesirable generation of stoichiometric metallic waste, these conditions limit...

DFT study on the mechanisms of α‐C cross coupling of π‐bonds catalyzed by iron complexes

“…Wang and co‐workers [ 18 ] suggested a possible catalytic cycle of the alkyne‐aldehyde coupling reaction catalyzed by iron complexes and then investigated the alkyne α‐C−H functionalization mechanism using the experimental method in 2020, [ 35 ] but the detailed mechanisms of the reaction have not been investigated. For example, what is the energy barrier of each step in the whole catalytic cycle?…”

“…It is probably due to the influence of ion participation in the reaction step and indicates that the reaction in this step is thorough and rapid in thermodynamics, which also meets with the experimental results of Wang and co‐workers. [ 35 ]…”

“…Furthermore, it means that the dissociative step will become the rate‐determining step in the whole catalytic cycle, which is contrary to the experimental result of Wang et al that the deprotonation step is the rate‐determining step. [ 35 ]…”

Looking deep into C–H functionalization: the synthesis and application of cyclopentadienyl and related metal catalysts

“…Expanding upon their previously reported method for Cp*Fe-catalyzed functionalization of allylic and propargylic C-H bonds with carbonyls, 104 Wang and coworkers reported benzylic functionalizations of carbamateprotected tetrahydroisoquinolines (Scheme 41A and B). 105 Here, Ph 3 CBF 4 is used as a hydride acceptor to generate the requisite iminium ion in situ. For alkyne-based processes, C-C bond formation is proposed to involve an Fe-allenyl species, which is generated by deprotonation (by sym-collidine) of an Scheme 40 Synthesis of [FeCp*(L Me )Me], application on C-H activation and proposed mechanism.…”

“…107,108 Scheme 41 Application of [FeCp*(THF)(CO) 2 ] on aC-H activation of p-bonds. 105 pyridines (Scheme 43C and D). 108 In each case, heteroatomdirected C-H metalation pathways were proposed, and alkenedependant branched to linear selectivities mirrored those outlined above.…”