《Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans》 was written by Kolarikova, Viola; Rybackova, Marketa; Svoboda, Martin; Kvicala, Jaroslav. Reference of Benzylidenebis(tricyclohexylphosphine)dichlororuthenium And the article was included in Beilstein Journal of Organic Chemistry in 2020. The article conveys some information:
The prochiral 4-(allyloxy)hepta-1,6-diynes, optionally modified in the positions 1 and 7 with an alkyl or ester group, undergo a chemoselective ring-closing enyne metathesis yielding racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans. Among the catalysts tested, Grubbs 1st generation precatalyst in the presence of ethene (Mori conditions) gives superior results compared to the more stable Grubbs or Hoveyda-Grubbs 2nd generation precatalysts. This was probably caused by a suppression of the subsequent sidereactions of the enyne metathesis product with ethene. On the other hand, the 2nd generation precatalysts gives better yields in the absence of ethene. The metathesis products, containing both a triple bond and a conjugated system, can be successfully orthogonally modified. For example, the metathesis product of 5-(allyloxy)nona-2,7-diyne reacted chemo- and stereoselectively in a Diels-Alder reaction with N-phenylmaleimide affording the tricyclic products as a mixture of two separable diastereoisomers, the configuration of which was estimated by DFT computations. The reported enediyne metathesis paves the way to the enantioselective enyne metathesis yielding chiral building blocks for compounds with potential biol. activity, e.g., norsalvinorin or cacospongionolide B. In the experiment, the researchers used many compounds, for example, Benzylidenebis(tricyclohexylphosphine)dichlororuthenium(cas: 172222-30-9Reference of Benzylidenebis(tricyclohexylphosphine)dichlororuthenium)
Benzylidenebis(tricyclohexylphosphine)dichlororuthenium(cas: 172222-30-9) is the first metathesis catalyst to be widely used in organic synthesis. It is useful for acyclic diene metathesis polymerization (ADMET), Ring-Opening Metathesis Polymerization (ROMP) of strained cyclic olefins, ring opening metathesis (ROM), and so on.Reference of Benzylidenebis(tricyclohexylphosphine)dichlororuthenium
Referemce:
Chloride – Wikipedia,
Chlorides – an overview | ScienceDirect Topics