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

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.

Palladium-Catalyzed Cascade Dearomative Spirocyclization and C-H Annulation of Aromatic Halides with Alkynes.

Described herein is a palladium-catalyzed intermolecular dearomative annulation of aryl halides with alkynes, which provides a rapid approach to a class of structurally unique spiroembedded polycyclic aromatic compounds. The cascade process is accomplished by a sequential alkyne migratory insertion, Heck-type dearomatization, and C-H bond annulation. Further optoelectronic study indicated this fused spirocyclic scaffold could be a potential host material for OLEDs, as exemplified by a fabricated red PhOLED device with a maximum external quantum efficiency of 23.

Highly Chemo-, Regio- and E/Z-Selective Intermolecular Heck-Type Dearomative [2 + 2 + 1] Spiroannulation of Alkyl Bromoarenes with Internal Alkynes.

Described herein is a palladium-catalyzed dearomative annulation of alkyl bromoarenes with internal alkynes. Challenges in this spiroannulation include the chemoselectivity among [2 + 2 + 1], [2 + 2 + 2], and [3 + 2] annulations and the E/ Z-selectivity associated with the generated exocyclic double bond. In the presence of Pd(OAc) and a phosphine ligand, a variety of highly functionalized spirocyclopentadienes with an exocyclic carbon-carbon double bond are provided in good to excellent yields with high chemo-, regio-, and E/ Z-selectivity via a Heck-type pathway.

Rhodium/Copper Cocatalyzed Highly trans-Selective 1,2-Diheteroarylation of Alkynes with Azoles via C-H Addition/Oxidative Cross-Coupling: A Combined Experimental and Theoretical Study.

Transition metal-catalyzed addition of diaryl alkynes with arylating reagents for the synthesis of tetraarylethylenes generally encounters rigorous reaction conditions and relies on the use of prefunctionalized substrates such as organic halides or surrogates and organometallic reagents. In this work, we establish a highly trans-selective 1,2-diheteroarylation of alkynes with azoles via a rhodium/copper cocatalyzed C-H addition/oxidative coupling process. Moreover, the diheteroarylation developed herein could open a door for the synthesis of heteroarene-doped tetraarylethylenes, and the photoluminescence (PL) spectra in THF-water mixtures and solid powder verify that these tetra(hetero)arylethylenes are aggregation-induced emission (AIE) active, building a new AIE molecule library.

Copper- or Nickel-Enabled Oxidative Cross-Coupling of Unreactive C(sp)-H Bonds with Azole C(sp)-H Bonds: Rapid Access to β-Azolyl Propanoic Acid Derivatives.

β-Azolyl propanoic acid derivatives are frequently found in biologically active molecules and pharmaceuticals. Here, we report the oxidative heteroarylation of unactivated C(sp)-H bonds with azole C(sp)-H bonds via copper or nickel catalysis with the aid of removable bidentate auxiliary, which provides a rapid pathway to β-azolyl propanoic acid derivatives. A variety of azoles such as oxazole, benzoxazole, thiazole, benzothiazoles, benzimidazole, purine, and even [1,2,4]triazolo[1,5-a]pyrimidine could be engaged in this protocol.

Cobalt-Catalyzed Oxidative C-H/C-H Cross-Coupling between Two Heteroarenes.

The first example of cobalt-catalyzed oxidative C-H/C-H cross-coupling between two heteroarenes is reported, which exhibits a broad substrate scope and a high tolerance level for sensitive functional groups. When the amount of Co(OAc)2 ⋅4 H2 O is reduced from 6.0 to 0.

Expression of alpha and beta Genes of Human Hemoglobin in Escherichia coli.

Total RNA was isolated from human erythrocyte. cDNA fragments coding for alpha and beta genes of human hemoglobins were obtained through RT-PCR and were ligated to plasmid pT7-Blue. Then fragments of alpha and beta genes were cut off and ligated with plasmid pBV220.