Heck-Cassar-Sonogashira-Hagihara

The Heck-Cassar-Sonogashira-Hagihara system, which couples terminal alkynes and vinylic or aromatic halides in an amine solvent, typically piperi-... 

The first synthesis of PPEs was published by Schulz and Giesa in 1990 [3]. They reacted dibromodi(alkoxy)benzenes with different di(ethynyl)di(alkoxy)arenes in the presence of a Pd catalyst in an amine (Heck-Cassar-Sonogashira-Hagihara reaction) [4]. They obtained low molecular weight... 

The name of Sonogashira (or Sonoga-shira-Hagihara) is commonly employed to identify this reaction, while even for the copper-free procedures Heck and Cassar are rarely mentioned. 

Direct introduction of sp carbon to alkynes by the reaction of Cu acetylides with aryl and alkenyl halides to form arylalkynes and alkenylalkynes is known as the Castro reaction [1]. Later it was found that coupling of terminal alkynes (1-alkynes) with halides proceeds more smoothly by using Pd catalysts. There are two methods of Pd-catalyzed coupling, hi 1975 direct coupling of 1-alkynes catalyzed by a phosphine-Pd(O) complex in the presence of amines was reported by Heck and Cassar as an extension of the Heck reaction to 1-alkynes [2,3]. In the same year, Sonogashira and Hagihara found that the addition of Cul as a co-catalyst gave better results, and the Pd(0)-CuI-catalyzed reaction is called the... 

---