Transition‐Metal‐Free Cross‐Coupling of Benzothiophenes and Styrenes in a Stereoselective Synthesis of Substituted (E,Z)‐1,3‐Dienes

A transition metal‐free one‐pot stereoselective approach to substituted (E,Z)‐1,3‐dienes was developed by using an interrupted Pummerer reaction/ligand‐coupling strategy. Readily available benzothiophene S‐oxides, which can be conveniently prepared by oxidation of the parent benzothiophenes, undergo Pummerer coupling with styrenes. Reaction of the resultant sulfonium salts with alkyllithium/magnesium reagents generates underexploited hypervalent sulfurane intermediates that undergo selective ligand coupling, resulting in dismantling of the benzothiophene motif and the formation of decorated (E,Z)‐1,3‐dienes.     

Generation and detection of tellurane [10-Te-4(C4)] and selenurane [10-Se-4(C4)] having alkyl and aryl ligands

Formation of 2,2′-biphenylylenedimethylselenurane and -tellurane was observed by the ¹H, ¹³C, ⁷⁷Se, and ¹²⁵Te NMR studies at low temperature, in the reactions of dibenzoselenophene Se-oxide and 2,2′-biphenylylenedibromotellurane with methyllithium. These hypervalent compounds were unstable and decomposed at room temperature to give the corresponding dibenzochalcogenophenes quantitatively.