Carbon–Carbon Bond Formation at a Neutral Terminal Carbido Ligand: Generation of Cyclopropenylidene and Vinylidene Complexes

Abstract

A C1 source, the carbido complex [Ru(C)(PCy3)2Cl2] (1) adds cleanly to dimethylacetylene dicarboxylate (DMAD), affording the cyclopropenylidene complex 2 (red O, green Cl, yellow P, gray C). This product is surprising given the instability of its trans‐cyclopropylidene analogue. HX reagents effect 1,1‐addition and ring opening, forming vinylidene complexes such as 3 which catalyze the ring‐opening metathesis polymerization of norbornene.

Enolesters as chain end‐functionalizing agents for the living ring opening metathesis polymerization

“…An immediate shift of the carbene proton signal from 20.7 to 15.8 ppm was observed. Furthermore, this acyl‐Fischer‐carbene reacted with EVE to form the vinyl ether Fischer carbene with a carbene signal at 14.7 ppm in a Fischer‐carbene to Fischer‐carbene transformation. While the observed upfield shift of the carbene signal was in agreement with the respective π‐donation strength of oxygen lone pairs on EVE and VA , the NMR experiment gave no indication about a loss of regioselectivity.…”

Addition of alkynes and osmium carbynes towards functionalized dπ–pπ conjugated systems

“…4), a series of reactant osmapentalynes (1b-1g) were synthesized by the treatment of carbon ligands (L2-L7) with multiyne chains with OsCl 2 (PPh 3 ) 3 and PPh 3 , the different substituents at different positions appear not to affect the reaction (3,(31)(32)(33)(34)(35)(36). For instance, the R′ substituent can be styryl (3), phenyl (31)(32)(33), thienyl (34) or hydrogen (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46), and the Y group can be CH 2 (31,34), O (32,35) or C(COOMe) 2 (33,36). The structures of all the above complexes were confirmed by NMR spectroscopy, EA and HRMS ( Supplementary Figs.…”

“…The reactions of M≡C and C≡C bonds tend to afford cycloaddition intermediates or products on account of their high degree of unsaturation. For example, the alkyne metathesis undergoes metallacyclobutadiene intermediates process 12-14 , and [2+2], [2+2+1], and [2+2+2] cycloaddition products have been widely published [26][27][28][29][30][31][32][33][34][35][36][37] . Acyclic products, however, have never been reported.…”

The Versatile Alkylidene Moiety in Ruthenium Olefin Metathesis Catalysts

“…The order of the activity for NHC vinylidenes in ROMP and RCM was: 38 > 39 > 37 . Johnson et al reported28 some noteworthy unique vinylidine complexes 42 – 46 . These complexes were prepared starting from the rare neutral terminal carbido complex 40 which is surprisingly stable12 and undergoes [2+1] addition with dimethyl acetylenedicarboxylate (DMAD) to yield the cyclopropenylidene complex 41 .…”