Visible-Light-Initiated Decarboxylative Alkylation of Quinoxalin-2(1H)-ones with Phenyliodine(III) Dicarboxylates in Recyclable Ruthenium(II) Catalytic System

Abstract

A efficient and sustainable approach for the synthesis of 3-alkylquinoxalin-2­(1H)-ones has been developed through visible-light-mediated decarboxylative alkylation of quinoxalin-2­(1H)-ones with phenyliodine­(III) dicarboxylates. This photocatalytic alkylation reaction could be conducted at ambient temperature by employing eco-friendly PEG-200 as the reaction medium. Various 3-alkylquinoxalin-2­(1H)-ones were easily obtained through the present ruthenium­(II) catalytic system, which could be successfully recycled five times without the significant decrease of its efficiency.

Metal‐Free C3 Hydroxylation of Quinoxalin‐2(1H)‐ones in Water

“…The low yield of the transformation was probably due to the poor solubility of 1 a in water. Various oxidants were also investigated, revealing that (NH 4 ) 2 S 2 O 8 is more suitable for the transformation (entries [8][9][10][11]. To our delight, the yield of 2 a was improved to 61% (entry 2).…”

“…Next, a series of surfactants [13] (entries 3-7) were surveyed and DL-α-Tocopherol methoxypolyethylene glycol succinate solution (2 wt% in water) (TPGS-750-M) was found to be the most efficient surfactant for this hydroxylation reaction (entry 7). Various oxidants were also investigated, revealing that (NH 4 ) 2 S 2 O 8 is more suitable for the transformation (entries [8][9][10][11]. Increasing the loading of (NH 4 ) 2 S 2 O 8 to 3 equiv.…”

“…As a part of our ongoing interest in functionalization of quinoxalin-2(1H)-ones, [11] herein we reported a sustainable method for the clean preparation of various mono N-functionalized quinoxaline-2,3(1H,4H)-diones through direct hydroxylation of N-functionalized quinoxalin-2(1H)-ones in water (Scheme 1b). In the present reaction, the desired product can be obtained through simple extraction and recrystallization without tedious column chromatography.…”

Recyclable Perovskite as Heterogeneous Photocatalyst for Aminomethylation of Imidazo‐Fused Heterocycles

“…Furthermore, additional experiments using ammonium oxalate as hole scavenger [9b] or K 2 S 2 O 8 as electron scavenger [17] gave the product 3 a in lower yields, suggesting that both hole and electron played key roles in the photocatalytic process (for details see the Supporting Information). Based on the accumulated experimental evidences and previous literature reports, [18] a proposed mechanism for this photocatalytic transformation is outlined in Scheme 4. Upon irradiation by visible light, the absorption of a photon in CsPbBr 3 leads to the formation of an electron (e À ) and a hole (h + ) that can act as single electron donor and acceptor in the desired organic transformations, respectively.…”

Metal Free Benzylation and Alkylation of Quinoxalin‐2(1H)‐ones with Alkenes Triggered by Sulfonyl Radical Generated from Sulfinic Acids

“…[2] Consequently, several reports have been documented to synthesize C3substituted quinoxalin-2(1H)-ones. [3] While much development has been made with respect to arylation, [3a-j] acylation, [3k-l] amination, [3m-q] phosphonylation [3r-s] directly at the C3 position using easily available quinoxalin-2(1H)-ones, functionalization by benzyl, [4] alkyl [5] and fluoroalkyl [6] groups are less explored, despite the importance and predominance of this scaffold as pharmaceuticals that include MDR antagonist, aldose reductase inhibitor, MAO-A inhibitor, ion channel blocker, antitumor, anti-inflamatory, and anti-obesity agents ( Figure 1). [7][8][9] Very recently, C3 position of quinoxalin-2(1H)-one has been directly benzylated [4] and alkylated [10] using methylarenes and ethers, respectively (Scheme 1a).…”