NHPI and palladium cocatalyzed aerobic oxidative acylation of arenes through a radical process

Molecular oxygen, the most environmentally friendly oxidant, was used as the terminal oxidant for palladium-catalyzed radical oxidative acylation of arenes.

Dramatically different charge transport properties of bisthienyl diketopyrrolopyrrole-bithiazole copolymers synthesized via two direct (hetero)arylation polymerization routes

Two diketopyrrolopyrrole-bithiazole copolymers with same building blocks synthesized via direct (hetero)arylation polymerization through different routes show dramatically different charge transport properties.

Bulky α-diimine palladium complexes: highly efficient for direct C–H bond arylation of heteroarenes under aerobic conditions

Through the strategy to enhance the bulkiness on both the backbone and the N-aryl moieties, we designed and synthesized a type of bulky α-diimine palladium complex (i.e., {[Ar–NC(R)–C(R)N–Ar]PdCl₂, (Ar = 2-benzhydryl-4,6-dimethylphenyl)}, C1, R = H; C2, R = An; C3, R = Ph).

Regioselectivity in palladium-catalysed direct arylation of 5-membered ring heteroaromatics

In the past few years, several results using modified catalysts and new reaction conditions have been reported permitting better control of the regioselectivity of Pd-catalysed arylations.

α-Iminonitrile: a new cyanating agent for the palladium catalyzed C–H cyanation of arenes

An efficient palladium-catalyzed C–H cyanation reaction of arenes using α-iminonitrile as a new cyanating reagent has been developed.

Microwave-assisted regioselective direct C–H arylation of thiazole derivatives leading to increased σ1 receptor affinity

Regioselective direct CH arylation of 2a led to thiazoles 2b and 2c with a 4-tolyl moiety in C5- and C4-position displaying 5- to 9-fold increased σ₁ affinity.

C-H arylation and alkenylation of imidazoles by nickel catalysis: solvent-accelerated imidazole C-H activation

The first nickel-catalyzed C-H arylations and alkenylations of imidazoles with phenol and enol derivatives are described. Under the influence of Ni(OTf)2/dcype/K3PO4 (dcype: 1,2-bis(dicyclohexylphosphino)ethane) in t-amyl alcohol, imidazoles can undergo C-H arylation with phenol derivatives. The C-H arylation of imidazoles with chloroarenes as well as that of thiazoles and oxazoles with phenol derivatives can also be achieved with this catalytic system. By changing the ligand to dcypt (3,4-bis(dicyclohexylphosphino)thiophene), enol derivatives could also be employed as coupling partners achieving the C-H alkenylation of imidazoles as well as thiazoles and oxazoles. Thus, a range of C2-arylated and alkenylated azoles can be synthesized using this newly developed nickel-based catalytic system. The key to the success of the C-H coupling of imidazoles is the use of a tertiary alcohol as solvent. This also allows the use of an air-stable nickel(ii) salt as the catalyst precursor.

Thiazole formation through a modified Gewald reaction

The synthesis of thiazoles and thiophenes starting from nitriles, via a modified Gewald reaction has been studied for a number of different substrates. 1,4-Dithiane-2,5-diol was used as the aldehyde precursor to give either 2-substituted thiazoles or 2-substituted aminothiophenes depending on the substitution of the α-carbon to the cyano group.

Facile synthesis of 2,5-disubstituted thiazoles from terminal alkynes, sulfonyl azides, and thionoesters

A sequential procedure for the synthesis of 2,5-disubstituted thiazoles from terminal alkynes, sulfonyl azides, and thionoesters is reported. A copper(I)-catalyzed 1,3-dipolar cycloaddition of terminal alkynes with sulfonyl azides affords 1-sulfonyl-1,2,3-triazoles, which then react with thionoesters in the presence of a rhodium(II) catalyst. The resulting 3-sulfonyl-4-thiazolines subsequently aromatize into the corresponding 2,5-disubstituted thiazoles by elimination of the sulfonyl group.

Ruthenium(II)-catalyzed C-H activation/alkyne annulation by weak coordination with O2 as the sole oxidant

Aerobic oxidative CH functionalizations of weakly coordinating benzoic acids have been accomplished with versatile ruthenium(II) biscarboxylates under ambient oxygen or air. Mechanistic studies identified the key factors controlling the elementary step of the oxidation of the ruthenium(0) complex.

Synthesis and characterization of hexaarylbenzenes with five or six different substituents enabled by programmed synthesis

Since its discovery in 1825, benzene has served as one of the most used and indispensable building blocks of chemical compounds, ranging from pharmaceuticals and agrochemicals to plastics and those used in organic electronic devices. Benzene has six hydrogen atoms that can each be replaced by different substituents, which means that the structural diversity of benzene derivatives is intrinsically extraordinary. The number of possible substituted benzenes from n different substituents is (2n + 2n(2) + 4n(3) + 3n(4) + n(6))/12. However, owing to a lack of general synthetic methods for making multisubstituted benzenes, this potentially huge structural diversity has not been fully exploited. Here, we describe a programmed synthesis of hexaarylbenzenes using C-H activation, cross-coupling and [4+2] cycloaddition reactions. The present method allows for the isolation and structure-property characterization of hexaarylbenzenes with distinctive aryl substituents at all positions for the first time. Moreover, the established protocol can be applied to the synthesis of tetraarylnaphthalenes and pentaarylpyridines.