Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs2CO3-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

The synthesis of benzimidazo[2,1-b]benzoselenoazoles is described. The novel ring-closure reaction of 1-(2-bromoaryl)benzimidazoles with Se powder is promoted by Cs₂CO₃ (2 equiv) in DMF at 150 °C. Moreover, the obtained tetracyclic heterocycles are all novel compounds. Single-crystal X-ray analysis of the parent benzimidazo[2,1-b]benzoselenoazole revealed that the tetracyclic ring is almost planar. Absorption spectroscopy data of the benzimidazo[2,1-b]benzoselenoazoles showed the λ_max was dependent on the number of rings.

Photoinduced synthesis of unsymmetrical diaryl selenides from triarylbismuthines and diaryl diselenides

A novel method of photoinduced synthesis of unsymmetrical diaryl selenides from triarylbismuthines and diaryl diselenides has been developed. Although the arylation reactions with triarylbismuthines are usually catalyzed by transition-metal complexes, the present arylation of diaryl diselenides with triarylbismuthines proceeds upon photoirradiation in the absence of transition-metal catalysts. A variety of unsymmetrical diaryl selenides can be conveniently prepared by using this arylation method.

Ruthenium(III) acetylacetonate [Ru(acac)3] — An efficient recyclable catalyst for the acetylation of phenols, alcohols, and amines under neat conditions

A catalytic amount of ruthenium(III) acetylacetonate (2 mol%) [Ru(acac)3] enables solvent-free acetylation of phenols, alcohols, and amines at ambient temperature in good to excellent yields. Furthermore, the catalyst could be recovered and reused at least three times without a significant loss in yields.Key words: acetylation, protecting groups, ruthenium(III) acetylacetonate, phenols, alcohols, amines.

Ruthenium(III) acetylacetonate [Ru(acac)3] — An efficient chemoselective catalyst for the tetrahydropyranylation (THP) of alcohols and phenols under solvent-free conditions

A catalytic amount of ruthenium(III) acetylacetonate (2 mol%) [Ru(acac)3] enables solvent-free tetrahydropyranylation of different types of alcohols and phenols at ambient temperature in moderate to excellent yields. Notably, selective monoprotection of diols can be achieved chemoselectively. Furthermore, the catalyst could be recovered and reused if necessary.Key words: tetrahydropyranyl ethers, protecting groups, ruthenium(III) acetylacetonate, alcohols, thiols.