Sonogashira coupling alkenyl-alkynyl

Sonogashira coupling of o-iodothioanisole (73) with phenylacetylene affords o-(l-alkynyl)thioanisole 74, which cyclizes to give 2-substituted 3-iodobenzothio-phene 75 by the treatment with iodine. Furthermore, Suzuki coupling of 75 affords the 2,3-disubstituted benzothiophene 76 [45]. The iminoalkyne 78 is prepared by Sonogashira coupling of the alkenyl iodide 77, and the substituted pyridine 79 is obtained by the Cul-catalyzed cyclization [46]. 

Sonogashira reaction [4,5], A comprehensive review on Pd-catalyzed alkynylation was published recently by Negishi and Anastasia [6], Facile Pd(0)-CuI-catalyzed coupling of aryl and alkenyl halides with 1-alkynes is used extensively for the preparation of arylalkynes or enynes. 

Reddy and collaborators reported a new one-pot, three-component procedure toward the synthesis of novel 4-phenyl-2-[3-(alkynyl/alkenyl/aryl) phenyl] pyrimidine libraries starting with the Michael addition of enaminone 64 with 3-bromobenzimidamide hydrochloride (65) (Scheme 28) (13S75). This was followed by a cyclization, an isomerization, a dehydration, and a subsequent Sonogashira reaction with terminal alkynes or a Suzuki reaction with arylboronic acids or a Heck coupling reaction with alkenes. 

Sonogashira cross-coupling is another typical palladium-catalyzed process consisting of the alkynylation of aryl or alkenyl halides in the presence of Cu(I) salts [46]. 

The intra-intermolecular Heck reaction of dienediol bisnonaflates containing an (O-alkenyl substituent with an external alkene such as an acrylate gives rise to the formation of a bicyclic tetraene by an intramolecular coupling followed by an intermolecular Heck or Sonogashira-type reaction (Scheme 5-30, Experimental Procedure below).It should be noted that the alkynylation proceeds in absence of copper additives. 

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