Synthesis of gem-dihaloenynes and butatrienes from gem-dihalovinyl derivatives

Copper-Catalyzed Formal Dehydration Polymerization of Propargylic Alcohols via Cumulene Intermediates

Here we report a copper-catalyzed formal dehydration polymerization of propargylic alcohols. Copper catalysis allows for efficient in situ generation of [n]cumulenes (n = 3, 5) by a soft deprotonation/β-elimination pathway and subsequent polymerization via organocopper species. Alkyne polymers (M_n up to 36.2 kg/mol) were produced with high efficiency (up to 95% yield) and excellent functional group tolerance. One-pot synthesis of semiconducting head-to-head poly(phenylacetylene) was demonstrated through a polymerization-isomerization sequence.

Synthesis of alkynes from non-alkyne sources

This review contains a compilation of the literature for the synthesis of alkynes from non-alkyne sources.

Na2S-mediated synthesis of terminal alkynes from gem-dibromoalkenes

The Na₂S-mediated facile synthesis of terminal alkynes from gem-dibromoalkenes, at 20/40 °C under open flask conditions has been developed.

Synthesis of Sterically-Crowded Olefins, gem-Dihaloalkenes, Butatrienes, and Thioketenes through the Reaction of Substituted Bornane-2-thiones or Bornane-2-selones with Conventional Carbenes or Metal Carbenoids

Reaction of highly-substituted bornane-2-selones with a diazoalkane in the presence of either Rh2(OAc)4 or CuCl formed sterically-crowded exo-methylenic products, and similar treatment of the thiones or selones with dihalocarbenes or a propadienylidene carbene also formed dihaloalkenes, butatrienes, and thioketenes. All these reactions were assumed to proceed through a pathway involving the in situ formation and subsequent ring closure of chalcogenocarbonyl ylides.