Pd-catalyzed cross-electrophile Coupling/C–H alkylation reaction enabled by a mediator generated via C(sp³)–H activation

Abstract

Transition-metal-catalyzed cross-electrophile C(sp2)–(sp3) coupling and C–H alkylation reactions represent two efficient methods for the incorpration of an alkyl group into aromatic rings. Herein, we report a Pd-catalyzed cascade cross-electrophile coupling...

Remote C(sp3)–H activation: palladium-catalyzed intermolecular arylation and alkynylation with organolithiums and terminal alkynes

“…On the basis of both our aforementioned results and previous studies reported in the literature, 2–11 we proposed a mechanism for the palladium-catalyzed C(sp 3 )–H activation coupling reaction proceeding by a 1,4-Pd shift (Scheme 6). Initially, the Pd (0) catalyst coordinates to substrate 1a providing intermediate A , which undergoes oxidative addition to generate Pd( ii ) intermediate B .…”

“…In the past two decades, palladium-catalyzed activation of remote C(sp 3 )–H has emerged as a powerful method for the construction of a variety of C–C bonds, 1 most of which rely on the deployment of the 1,4-palladium shift strategy. 2,5–11 As can be seen in Scheme 1, the in situ -generated diorganopalladacycle A via oxidative addition of Pd(0) to a C(sp 2 )–X bond and further cleavage of the proximate intramolecular C(sp 3 )–H bond leads to potential transformations. Alternatively, the ring-opening of palladacycle A through protonation or oxidative addition/reductive elimination provides an σ-alkylpalladium complex B , hence resulting in an overall 1,4-palladium shift as initially observed by Dyker.…”

“…6 b Soon after, Lin and co-workers reported a palladium-catalyzed alkyl C–H borylation with aryl bromides, furnishing alkyl boronates. 7 It must also be pointed out that Luan, 8 Zhang, 9 Martin 10 and Yang 11 have all contributed significantly to the palladium-catalyzed activation of inert C(sp 3 )–H bonds.…”

Intermolecular Difunctionalization of C,C-Palladacycles Obtained by Pd(0)-Catalyzed C–H Activation

“…In contrast to ortho -iodo- tert -butylbenzenes, ortho -iodoanisoles were dialkylated to form ortho -dialkyl anisoles (Scheme ). A methoxy group is sterically smaller than a tert -butyl group, so in the palladacycles derived from a methoxy group, steric clashing with the newly introduced alkyl group is attenuated compared to tert -butyl-derived palladacycles. As a consequence, the second C , C -palladacycles did not undergo reductive elimination, and they reacted with a second alkyl chloride molecule to form dialkylated anisoles as the final products.…”

Palladium-catalyzed triple coupling of 2-iodoanisoles with aryl iodides to access 6H-dibenzopyrans

“…Based on the control experiments and related reports, 21,22 a putative mechanism was illustrated in Scheme 3. Firstly, 2-iodoanisole 1a undergoes oxidative addition with Pd(0) to give a Pd( ii ) complex A .…”