Diynes, reactions with metal complexes ruthenium

Addition of diazo compounds to metallic complexes allows the formation of metal carbenoid species which can react with unsaturated molecules to form new carbon-carbon bonds. The Cp RuCl(cod)-catalyzed addition of diazo compoimds to alkynes led to the selective synthesis of functional 1,3-dienes by the combination of two molecules of diazoaUcane and one molecule of alkyne [115,116] [Eqs. (53) and (54)]. The ruthenium carbene, generated from diazo compound, reacts with the C=C bond to produce vinylcarbene intermediate able to add a second molecule of diazo compotmd to generate dienes. The stereoselective formation of these conjugated dienes results from the selective creation of two C=C bonds, probably due to the possibility for (C5Me5)RuCl moiety to accomodate two cis carbene ligands. This reaction occurred with terminal or internal alkynes as well as 1,3-diynes [115] and was applied successfully to alkynylboronates [116]. 

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