Facile synthesis of benzo[: B] thiophenes via metal-free radical-triggered intramolecular C-S bond formation
A facile method for the synthesis of benzo[b]thiophenes with good to excellent yields via metal-free intramolecular C-S bond formation has been developed by utilizing I2 as a catalyst and O2 from air as an oxidant (20 examples). Its notable features such as catalytic I2, intramolecular C-S bond formation, short reaction times, and broad functional group tolerance make this strategy highly attractive. The purification of products only needs washing with solvents, thereby avoiding traditional chromatography and recrystallization, which belongs to group-assisted purification (GAP) chemistry.
Fan, Wei,Chen, Kwong-Yuen,Chen, Qi-Peng,Li, Guigen,Jiang, Bo
Intramolecular S···O chalcogen bond in thioindirubin
Results of X-ray diffraction study and quantum-chemical calculations revealed that molecular conformation of thioindirubin molecule creates suitable conditions for formation of intramolecular C-H···O and S···O interactions. Analysis of molecular electrostatic potential (MEP) demonstrates existence of two areas of positive MEP (σ-holes) in the outermost part of the sulfur atom on the continuation of the lines of the C-S bonds. One of these σ-holes is oriented toward region of negative MEP around the oxygen atom of carbonyl group. Such situation corresponds to formation of σ-hole or chalcogen bond. Existence of both types of bonding interactions is confirmed by topological analysis of electron density distribution using "Atoms in Molecules" (AIM) theory. Energies of the C-H···O hydrogen bond and the S···O σ-hole bond derived from AIM and NBO theories are very close.
Shishkin, Oleg V.,Omelchenko, Irina V.,Kalyuzhny, Andrei L.,Paponov, Boris V.