Iridium(III)‐Catalyzed Intermolecular C(sp³)−H Insertion Reaction of Quinoid Carbene: A Radical Mechanism

Abstract

Described herein is an Ir III /porphyrin-catalyzed intermolecular C(sp 3 ) À Hi nsertion reaction of aq uinoid carbene (QC). The reaction was designed by harnessing the hydrogen-atom transfer (HAT) reactivity of am etal-QC species with aliphatic substrates followed by aradical rebound process to affordC À Harylation products.This methodology is efficient for the arylation of activated hydrocarbons such as 1,4-cyclohexadienes (down to 40 min reaction time,upto99% yield, up to 1.0 gs cale). It features unique regioselectivity, which is mainly governed by steric effects,asthe insertion into primary CÀHbonds is favored over secondary and/or tertiary CÀHb onds in the substituted cyclohexene substrates.M echanistic studies revealed ar adical mechanism for the reaction.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Computational insights into different regioselectivities in the Ir-porphyrin-catalyzed C–H insertion reaction of quinoid carbene

“…Very recently, Che and co-workers have developed ruthenium- and iridium-porphyrin quinoid carbene complexes ( Ru-QC and Ir-QC ) for the carbene-transfer and carbene-insertion reactions (Scheme 1b). 7 As shown in Scheme 2a, with the OEP ligand (OEP = octaethylporphyrin) in the Ir(OEP)Me-catalyzed C–H functionalization reaction of 1-methyl-1,3-cyclohexadiene 1 with quinone diazide 2 , the secondary C (a) –H arylated product 3a is the major product, which is consistent with the lower bond dissociation energy (BDE) of the secondary C (a) –H bond in 1 . In contrast, for 1-methylcyclohexene 4 which also contains both primary and secondary C–H bonds, the primary C–H arylated product 5 is the major product (Scheme 2b).…”

Lewis Acid-Promoted Oxidative Addition at a [Ni0(diphosphine)2] Complex: The Critical Role of a Secondary Coordination Sphere

“…In addition to [5] + , the fate of the "Ph" fragment is accounted for in the formation of several C6HnD6-n isotopologues that result from H/D exchange with C6D6 (see ESI). Performing this reaction in the presence of a radical scavenger, 2,2,6,6tetramethylpiperidin-1-yl)oxyl (TEMPO) 11 provides the corresponding phenyloxy adduct by 1 H NMR spectroscopy (Scheme 2). We contend that [5]I results from double iodine atom abstraction from PhI.…”

Lewis Acid‐Promoted Oxidative Addition at a [Ni0(diphosphine)2] Complex: The Critical Role of a Secondary Coordination Sphere

“…In addition to [5] + , the fate of the "Ph" fragment is accounted for in the formation of several C 6 H n D 6-n isotopologues that result from H/D exchange with C 6 D 6 (see the Supporting Information). Performing this reaction in the presence of a radical scavenger, 2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) [12] provides the corresponding phenyloxy adduct by 1 H NMR spectroscopy (Scheme 3). We contend that [5]I results from double iodine atom abstraction from PhI, though decomposition of a nickel(II) oxidativeaddition product, in the presence of excess DMAP, cannot be conclusively ruled out -it should be noted, however, that 2-F is stable in the presence of excess DMAP, generating a [(diphosphine)Ni(4-F-C 6 H 4 )(I)] compound with NÀ B linkages (see the Supporting Information).…”