Ligand-Free Copper-Catalyzed Regioselective C-2 Arylation of Imidazo[2,1-b]thiazoles

Transition Metal-Driven Selectivity in Direct C-H Arylation of Imidazo[2,1-b]Thiazole

A selective direct arylation of the different Csp2-H bonds of imidazo[2,1-b]thiazole with (hetero) aryl halides can be achieved simply by switching from a palladium catalyst system to the use of stoichiometric amounts of copper. The observed selectivity, also rationalized by DFT calculations, can be explained by a change in the mechanistic pathways between electrophilic palladation and base-promoted C-H metalation.

Synthesis and properties of a series of iridium complexes with imidazolo[2,1-b]thiazole derivatives as primary ligands

Ten novel phosphorescent iridium complexes based on imidazolo[2,1-b]thiazole derivatives as primary ligands with luminescent nearly full colors.

Copper-catalyzed oxidative multicomponent reaction: synthesis of imidazo fused heterocycles with molecular oxygen

An oxidative cascade that involves multicomponent reaction comprising a terminal alkyne, 2-amino N-heterocycle, benzyl or allylic bromide with molecular oxygen, delivering densely functionalized imidazo fused heterocycles, is described. This reaction features a cheap catalyst, a green oxidant, and readily available starting materials, which make the overall synthesis applicable in the quick access to relevant pharmaceutical molecules with imidazole derived heterocycles.

N,O π-Conjugated 4-Substituted 1,3-Thiazole BF2 Complexes: Synthesis and Photophysical Properties

A series of 1,3-thiazole-based organoboron complexes has been designed and synthesized by acylation of 2-amino 4-subsituted 1,3-thiazoles with (4-dimethylamino)benzoyl chloride and the subsequent BF₂ complexation reaction. The influence of substituents in position 4 of the thiazole ring on photophysical properties of the complexes has been investigated. Synthesized thiazolo[3,2-c][1,3,5,2]oxadiazaborinines mainly showed intensive fluorescence in solutions. Complex with a 4,5-unsubstituted thiazole unit demonstrated an aggregation induced emission (AIE) effect and a very high fluorescent quantum yield (94%) in the solid state because of the inhibition of π-π/π-n interactions in the molecular packing.

Copper-catalyzed Direct 2-Arylation of Benzoxazoles and Benzoimidazoles with Aryl Bromides and Cytotoxicity of Products

An efficient copper-catalyzed direct 2-arylation of benzoxazoles and benzoimidazoles with aryl bromides is presented. The CuI/PPh₃-based catalyst promotes the installation of various aryl and heteroaryl groups through a C-H activation process in good to excellent yields. The cytotoxicity of obtained 2-aryl benzoxazoles (benzoimidazoles) was also evaluated and 1-methyl-2-(naphthalen-1-yl)benzoimidazole showed potential cytotoxicity.

Iodine-mediated C–N and C–S bond formation: regioselective synthesis of benzo[4,5]imidazo[2,1-b]thiazoles

The regioselective synthesis of benzo[4,5]imidazo[2,1-b]thiazole derivatives via amination (C–N) and intramolecular cyclization (C–S) reactions in the presence of molecular iodine has been reported. This method is base and metal free and features inexpensive catalysts, with a simple procedure and a short reaction time.

Approach for 2-(arylthio)imidazoles and imidazo[2,1-b]thiazoles from imidazo[2,1-b][1,3,4]thiadiazoles by ring-opening and -reconstruction

Useful heterocyclic synthons of imidazo[2,1-b][1,3,4]thiadiazoles were developed to synthesize imidazo[2,1-b]thiazoles and 2-(arylthio)-1H-imidazoles under mild reaction conditions.

Direct trifluoromethylation of imidazoheterocycles in a recyclable medium at room temperature

Regioselective C–H trifluoromethylation of imidazoheterocycles with Langlois' reagent in a recyclable mixed medium of 1-butyl-3-methylimidazoliumtetrafluoroborate ([Bmim]BF₄) and water at room temperature has been developed.

Pd/Cu-cocatalyzed reigoselective arylation of thiazole derivatives at 2-position under ligand-free conditions

An efficient protocol for regioselective arylation of thiazole derivatives at the 2-position via palladium- and copper-catalyzed C–H bond activation under ligand-free conditions has been developed.

Advances in direct C–H arylation of 5,5- 6,5- and 6,6-fused-heterocycles containing heteroatoms (N, O, S)

This report aims to review the advances made in C–H arylation of 5,6, 6,6 and 5,5 fused-heterocyclic systems.

Asymmetric Mannich reactions of imidazo[2,1-b]thiazole-derived nucleophiles with (S(S))-N-tert-butanesulfinyl (3,3,3)-trifluoroacetaldimine

Asymmetric Mannich reactions of imidazo[2,1-b]thiazole-derived nucleophiles with (SS)-N-tert-butanesulfinyl (3,3,3)-trifluoroacetaldimine were found to proceed with reasonably good yields (55%-79%) and exceptionally high stereoselectivity (>99 : 1 dr). This method presents a general approach for the preparation of a new type of biologically relevant compounds containing pharmacophoric imidazo[2,1-b]thiazole and (trifluoro)ethylamine groups.

7-Benzyl-3-methyl-6-phenyl-imidazo[2,1-b][1,3]thia-zol-7-ium chloride 0.75-hydrate

Theasymmetric unit of the title salt, C₁₉H₁₇N₂S⁺·Cl⁻·0.75H₂O, contains two symmetrically independent formula units of the carbenium salt along with three water mol­ecules. The water mol­ecules are only 50% occupated, and one of them is positioned in a hydro­phobic pocket not forming any hydrogen bonds. The conformation of the independent cations is very similar, with dihedral angles of 61.0 (2) and 61.5 (3)° between the benzene rings. They form quasi-centrosymmetric couples via π–π stacking inter­actions between the benzene and imidazo[2,1-b]thia­zole rings [centroid–centroid distances = 3.718 (3) and 3.663 (3) Å]. In the crystal, O—H⋯Cl hydrogen bonds lead to the formation of a helical anion–water chain along the c-axis direction. The cations connect to the anion–water chain through C—H⋯Cl inter­actions, generating a three-dimensional supra­molecular network. O—H⋯S hydrogen bonds and C—H⋯O inter­actions also occur.

Copper-catalyzed CuAAC/intramolecular C-H arylation sequence: Synthesis of annulated 1,2,3-triazoles

Step-economical syntheses of annulated 1,2,3-triazoles were accomplished through copper-catalyzed intramolecular direct arylations in sustainable one-pot reactions. Thus, catalyzed cascade reactions involving [3 + 2]-azide-alkyne cycloadditions (CuAAC) and C-H bond functionalizations provided direct access to fully substituted 1,2,3-triazoles with excellent chemo- and regioselectivities. Likewise, the optimized catalytic system proved applicable to the direct preparation of 1,2-diarylated azoles through a one-pot C-H/N-H arylation reaction.