A convenient methodology for the synthesis of mono- and di-halogenated benzo[b]thiophenes is described herein, which utilizes copper(II) sulfate pentahydrate and various sodium halides in the presence of substituted 2-alkynylthioanisoles. The proposed method is facile, uses ethanol as a green solvent, and results in uniquely substituted benzo[b]thiophene structures with isolated yields up to 96%. The most useful component of this methodology is the selective introduction of bromine atoms at every available position (2–7) around the benzo[b]thiophene ring, while keeping position 3 occupied by a specific halogen atom such as Cl, Br or I. Aromatic halogens are useful reactive handles; therefore, the selective introduction of halogens at specific positions would be valuable in the targeted synthesis of bioactive molecules and complex organic materials via metal-catalyzed cross coupling reactions. This work is a novel approach towards the synthesis of dihalo substituted benzo[b]thiophene core structures, which provides a superior alternative to the current methods discussed herein.

No abstract

A series of dinuclear copper(I) oxalate complexes was synthesized by the direct acid-base reaction of Cu2O with oxalic acid in ethanol with a ligand, or in neat ligand. The complexes incorporated a variety of ligands L (L = triphenylphosphine, 1,2bis(diphenylphosphino)ethane, triphenylphosphite, diisopropyl sulfide, cyclooctadiene and cyclohexylisocyanide) and had the general formula LnCu(µ2-C2O4)CuLn (n = 1 or 2). The Cu I /Cu II mixed-valence trinuclear compound (iPr2S)2Cu I (C2O4)Cu II (C2O4)Cu I (iPr2S)2 was formed concomitantly with the target dinuclear Cu2C2O4(iPr2S)4 complex, shedding light on the mechanism of disproportionation of this family of complexes. With norbornadiene (nbd) as a ligand, however, a coordination polymer Cu2C2O4(nbd) was formed. Also, the same reaction with L = 2,9-dimethyl-1,10-phenanthroline or pyridine resulted in the known tetrahedral complex ions [CuLm] + (m = 2 or 4). Lastly, the ligand di-2-(1-di-(2-picolyl)amino)propyl 3 disulfide produced not the expected Cu(I) oxalate complex, but a Cu(II) picolylamine oxalate coordination polymer. All products were structurally characterized by single-crystal X-ray diffraction if soluble, and by powder X-ray diffraction methods if not.

The dinuclear molecule of the title compound, [Cu2(C2O4)(C18H15P)4]·2CH2Cl2, lies across an inversion center with a strictly planar bridging oxalate ligand coordinating two CuI ions via two pairs of O atoms. Two triphenyl­phosphine ligands also coordinate each symmetry-related CuI ion, resulting in a distorted tetra­hedral geometry [O—Cu—O = 80.57 (5)° and P—Cu—P = 125.72 (2)°]. In the crystal, there are two dichloro­methane solvent mol­ecules for each dinuclear complex.

In the title compound, [Cu(CH 3 CN) 4 ](C 2 HO 4)Á0.5C 2 H 2 O 4 Á-0.5CH 3 CN, the Cu I ion is coordinated by the N atoms of four acetonitrile ligands in a slightly distorted tetrahedral environment. The oxalic acid molecule lies across an inversion center. The acetonitrile solvent molecule is disordered across an inversion center and was refined with half occupancy. In the crystal, the hydrogen oxalate anions and oxalic acid molecules are linked via O-HÁ Á ÁO hydrogen bonds, forming chains along [010]. Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5649). metal-organic compounds m544 Royappa et al.