α-Bromoacrylic Acids as C1 Insertion Units for Palladium-Catalyzed Decarboxylative Synthesis of Diverse Dibenzofulvenes

Abstract

Herein α-bromoacrylic acids have been employed as C1 insertion units to achieve the palladium-catalyzed [4 + 1] annulation of 2-iodobiphenyls, which provides an efficient platform for the construction of diverse dibenzofulvenes. This protocol enables the formation of double C­(aryl)–C­(vinyl) bonds via a C­(vinyl)–Br bond cleavage and decarboxylation. It is particularly noteworthy that the method features a broad substrate scope, and various interesting frameworks, such as bridged ring, fused (hetero)­aromatic ring, and divinylbenzene, can be successfully incorporated into the products.

Chemoselective Transformations of Cyclic β-Bromoacrylic Acids with Palladacycles Formed by Aryl Iodides to Access Fused or Spiro Polycycles

“…Among them, of extraordinary interest to synthetic chemists are annulation reactions of palladacycles with various coupling partners (e.g., arynes, alkynes, aryl halides, diazo compounds, diaziridinones, dibromomethane, bromophenols, o -bromobenzoic acids, , etc.). Undoubtedly, the success for this field relies heavily on the development of coupling partners because of the construction of diverse polycyclic compounds caused by their incorporation. − Despite remarkable progress, these coupling reagents were still limited by a specific annulation mode and a single role. Therefore, exploring new coupling reagents for diverse transformations of palladacycles is still desirable.…”

Palladium-Catalyzed Sequential Vinyl C–H Activation/Dual Decarboxylation: Regioselective Synthesis of Phenanthrenes and Cyclohepta[1,2,3-de]naphthalenes

“…For instance, a convenient and general palladium-catalyzed aryne annulation to synthesize phenanthrenes via arylpalladium­(II) aryne insertion and an intramolecular exo/endo-Heck reaction was reported by the groups of Larock and Yao, respectively . Very recently, a C­(aryl), C­(aryl)-palladacycle generated from 2-iodobiphenyls underwent two cross-coupling steps to attain the functionalization of both carbon atoms, as discovered and developed by the Zhang, Wang, Song, Liu, Xiang, Yang and Liang, and Luan groups, providing a feasible and reliable sequential synthetic strategy for the construction of PAHs. Despite significant advancements, there are still some limitations: (1) Electron-withdrawing groups are required, and the regioselective carbopalladation of asymmetric arynes is totally uncontrollable.…”

Regioselective synthesis of spirocyclic pyrrolines via a palladium-catalyzed Narasaka–Heck/C–H activation/[4 + 2] annulation cascade reaction

“…For the insertion of an aromatic ring, cheap and readily available 2-chlorobenzoic acid, in sharp contrast to the unselective insertion of aryne or aryl halide, inserts into palladacycle with high regioselectivity because the palladacycle reacts with 2chlorobenzoic acids through two sequential C-C crosscouplings, and two C-C bonds are formed with excellent chemoselectivity. [83][84][85][86][87][88][89][90] Consequently, we commenced our initial investigation by employing g,d-unsaturated oxime ester 1a and 2-chlorobenzoic acid 2a as the model substrates (Table 1). Fortunately, the anticipated domino reaction of 1a and 2a was conducted in the presence of Pd(OAc) 2 , P(p-Tol) 3 and K 2 CO 3 in DMF at 140 C for 12 h under an argon atmosphere, generating the desired product 3aa in 15% yield (Table 1, entry 1).…”