Insight into Regioselective Control in Aerobic Oxidative C–H/C–H Coupling for C3-Arylation of Benzothiophenes: Toward Structurally Nontraditional OLED Materials

Abstract

The installation of (benzo)thiophene-containing biaryls via coupling reactions has become a staple in designing photoelectric materials. Undeniably, C−H/C−H cross-coupling reactions between two (hetero)aromatics would be a shortcut toward these structural fragments. While more reliable cross-coupling technologies are well-established to provide C2-arylated (benzo)thiophenes, efficient methods that arylate the C3-position remain underdeveloped. Herein we provide insight into the factors that determine regioselectivity switching for these cross-coupling reactions. X-ray crystallographic analysis gives solid evidence for the key roles of triflate in regioselective dearomatization and acetate in base-assisted anti-β-deprotonated rearomatization. The first isolation and X-ray characterization of a medium-sized dearomatized cyclometalated adduct involving both substrates provide extra insight into aerobic oxidative Ar−H/Ar−H cross-coupling reactions. The mechanistic breakthrough incubates the first example, enabling C−H/C−H-type C3-arylation of benzothiophenes. Finally, this chemistry is used to design blue-emitting thermally activated delayed fluorescence (TADF) materials with a helicene conformation that exhibit a high maximum external quantum efficiency of 25.4% in OLED.

Recent advances in rhodium-catalysed cross-dehydrogenative-coupling between two C(sp2)–H bonds

“…In 2021, You, Bin and co-workers presented their investigation of the C3-arylation of benzothiophenes with detailed mechanism experiments and DFT calculations (Scheme 59). 82 It was found that OTf − and OAc − anion play a crucial role in the reaction that X-ray crystallographic analysis showed the key role of OTf − in regioselective dearomatisation and OAc − in base-assisted anti -β-deprotonated rearomatisation.…”

Synthesis, Characterization, and Thin-Film Transistor Response of Benzo[i]pentahelicene-3,6-dione

“…A handful of studies are available for other types of devices, such as organic light emitting diodes [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ], organic solar cells [ 57 , 58 , 59 ], and hybrid DSSC [ 60 ] and perovskite solar cells [ 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ].…”

Palladium Supported on Porous Organic Polymer as Heterogeneous and Recyclable Catalyst for Cross Coupling Reaction

“…As Nobel reactions, the Suzuki reaction and Heck reaction have a wide range of applications in organic synthetic chemistry [ 1 , 2 , 3 , 4 ]. The bi-aryl products are multipurpose building blocks in pharmaceuticals, agrochemicals and semiconductor materials such as organic light emitting diodes [ 5 ]. The cross-coupling reaction is one of the most important methods for the direct synthesis of related products [ 6 ].…”