Synthesis of unsymmetrical 1,4-diarylbutadiynes by Stille coupling

The article examines the synthesis of unsymmetrical 1,4-diarylbutadiynes by stille coupling. The products were stored under argon in a freezer and used the next day for the coupling reaction. At room temperature the pure compounds turned partly insoluble within few hours. The inside temperature was kept at 15-20°C with the help of an dry ice/2-propanol bath. In case that the color changed to greenish, some additional hydroxylamine hydrochloride was added. After complete addition of 3-bromoprop-2-ynol, the cooling bath was removed and the suspension was stirred at rt for another 4 h. The ice bath was removed, and the deep red mixture was stirred at rt until all of the catalyst had dissolved and the color had turned green. THF and diethyl ether were dried over sodium/benzophenone. © 1997 American Chemical Society.