Catalytic Arene meta-C–H Functionalization Exploiting a Quinoline-Based Template

Abstract

Strong σ-coordination by a heteroatom containing directing group (DG) is one of the effective strategies for performing site-selective C–H functionalization. Despite tremendous progress in directed ortho-C–H functionalization, selective meta-C–H functionalization using strong σ-coordination remains extremely challenging. Herein, we introduce the 8-nitroquinoline-based DG to ensure the formation of a stable palladacycle which enables selective meta-alkenylation and acetoxylation of arenes. Kinetic experiments, ESI-MS, NMR, and DFT studies provided important information regarding the mechanism of the reaction. The scalability as well as diversification of the products have been examined and are expected to be beneficial in pharmaceutical and material sciences.

Accessing Remote meta‐ and para‐C(sp2)−H Bonds with Covalently Attached Directing Groups

“…[31] phenethyl sulfonate (R = H) meta-olefination [32] aryl alcohol and acid (R = OMe) meta-olefination [33] aryl sulfonates (R = OMe) meta-silylation meta-germanylation [34] benzylsulfonyl esters phenylacetic acids meta-olefination [36] benzyl sulfonyl esters meta-olefination [41] benzyl sulfonates meta-cyanation meta-alkylation [43] [44] aryl sulfonates meta-cyanation meta-alkylation meta-alkenylation [43] [44] [44] phosphonate benzyl phosphonates meta-olefination meta-acetoxylation meta-hydroxylation [37] Angewandte Chemie Reviews…”

“…[41] This template not only plays al arge part in stabilizing the palladacycle but also offers ahigh coordinating ability.T he quinoline-based directing group was found to be better in terms of both reactivity and selectivity than the pyridine-based directing group,w hile the presence of anitro or methoxy substituent was found to greatly increase the yield. [41] This template not only plays al arge part in stabilizing the palladacycle but also offers ahigh coordinating ability.T he quinoline-based directing group was found to be better in terms of both reactivity and selectivity than the pyridine-based directing group,w hile the presence of anitro or methoxy substituent was found to greatly increase the yield.…”

Palladium‐Catalyzed Directed meta‐Selective C−H Allylation of Arenes: Unactivated Internal Olefins as Allyl Surrogates

“…The coordination of an amino‐acid ligand, Ac‐Nle‐OH, with displacement of two acetic acid molecules, is entropically favored. The transition‐structure ts‐1′ has the characteristic [5,6]‐palladacycle conducive for C−H activation . The formation of a five‐membered palladacycle by the ligand strategically positions the amide oxygen for facile C−H activation by concerted metalation deprotonation (CMD; other possible ligand arrangements are not competitive, see Supporting Information, Section 2.9.2).…”

Remote meta‐C–H Cyanation of Arenes Enabled by a Pyrimidine‐Based Auxiliary

“…[2] In this regard, meta-a nd paraselective CÀHb ond activation of aromatic arenes stand as worthy examples. [3][4][5] Recently, meta-C À Ha lkylation and alkenylation have been achieved with the aid of strong coordinating pyrimidine-based template. [3][4][5] Recently, meta-C À Ha lkylation and alkenylation have been achieved with the aid of strong coordinating pyrimidine-based template.…”