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Upstream product

• 3329-88-2 pent-3-yn-1-yl 4-methylbenzenesulfonate 

Downstream Products

• 86994-11-8 4-(trimethylsilyl)-but-3-yn-1-yl p-methylbenzenesulfonate 
• 1598423-98-3 (Z)-3-(tributylstannyl)hex-3-ene-1,6-diyl bis(4-methylbenzene-sulfonate) 
• 285551-80-6 C₄₂H₃₆P₂ 

Relevant academic research and scientific papers

Highly Reactive Cationic Molybdenum Alkylidyne N-Heterocyclic Carbene Catalysts for Alkyne Metathesis

The tetracoordinated cationic molybdenum alkylidyne N-heterocyclic carbene (NHC) complexes [Mo(CC6H4-p-OMe)(IMes)(OCMe(CF3)2)2][BPh4] (Mo5) and [Mo(CC6H4-p-OMe)(IMes)(OCMe(CF3)2)2][B(ArF)4] (Mo6, IMes = 1,3-dimesitylimidazol-2-ylidene)) were synthesized from the pentacoordinated progenitor Mo(CC6H4-p-OMe)(IMes)(OCMe(CF3)2)2(OTf) (Mo4). Complexes Mo4-Mo6 were evaluated for their ability to catalyze the self-metathesis of several internal alkynes. The presence of a triflate group facilitates formation of a cationic species while preformation of the cationic molybdenum center in molybdenum alkylidyne NHC complexes indeed results in a strong increase in catalyst productivity and activity, also in the presence of functional groups, compared to previously reported neutral congeners. The most striking feature of this class of tetracoordinate cationic complexes is the excellent catalytic activity in the alkyne metathesis of non-protic substrates, thereby supporting our previously published proposal of a tetracoordinate cationic active species in alkyne metathesis formed from the neutral, pentacoordinate molybdenum alkylidyne NHC progenitors. Catalyst productivity, expressed as turnover number, reached 20 000 in the self-metathesis of 1-phenyl-1-propyne (S1) using Mo(CC6H4-p-OMe)(1,3-dimesitylimidazol-2-ylidene)(OCMe(CF3)2)2[B(ArF)4] (Mo6) and 5-(benzyloxy)-2-pentyne (S2) at catalyst loadings as low as 0.005 mol %.

"canopy Catalysts" for Alkyne Metathesis: Molybdenum Alkylidyne Complexes with a Tripodal Ligand Framework

A new family of structurally well-defined molybdenum alkylidyne catalysts for alkyne metathesis, which is distinguished by a tripodal trisilanolate ligand architecture, is presented. Complexes of type 1 combine the virtues of previous generations of silanolate-based catalysts with a significantly improved functional group tolerance. They are easy to prepare on scale; the modularity of the ligand synthesis allows the steric and electronic properties to be fine-tuned and hence the application profile of the catalysts to be optimized. This opportunity is manifested in the development of catalyst 1f, which is as reactive as the best ancestors but exhibits an unrivaled scope. The new catalysts work well in the presence of unprotected alcohols and various other protic groups. The chelate effect entails even a certain stability toward water, which marks a big leap forward in metal alkylidyne chemistry in general. At the same time, they tolerate many donor sites, including basic nitrogen and numerous heterocycles. This aspect is substantiated by applications to polyfunctional (natural) products. A combined spectroscopic, crystallographic, and computational study provides insights into structure and electronic character of complexes of type 1. Particularly informative are a density functional theory (DFT)-based chemical shift tensor analysis of the alkylidyne carbon atom and 95Mo NMR spectroscopy; this analytical tool had been rarely used in organometallic chemistry before but turns out to be a sensitive probe that deserves more attention. The data show that the podand ligands render a Mo-alkylidyne a priori more electrophilic than analogous monodentate triarylsilanols; proper ligand tuning, however, allows the Lewis acidity as well as the steric demand about the central atom to be adjusted to the point that excellent performance of the catalyst is ensured.

Molybdenum Alkylidyne Complexes with Tripodal Silanolate Ligands: The Next Generation of Alkyne Metathesis Catalysts

A new type of molybdenum alkylidyne catalysts for alkyne metathesis is described, which is distinguished by an unconventional podand topology. These structurally well-defined complexes are easy to make on scale and proved to be tolerant toward numerous functional groups; even certain protic substituents were found to be compatible. The new catalysts were characterized by X-ray crystallography and by spectroscopic means, including 95Mo NMR.

Catalysts for the alkyne metathesis

Organometallic compounds of the general formula (I), in which M=Mo, W, are claimed.

Practical new silyloxy-based alkyne metathesis catalysts with optimized activity and selectivity profiles

Triphenylsilanolate ligands were found to impart excellent reactivity and outstanding functional group tolerance on molybdenum alkylidyne complexes, which catalyze alkyne metathesis reactions of all sorts. The active species either can be obtained in high yield by adaptation of the established synthesis routes leading to Schrock alkylidynes or can be generated in situ from the molybdenum nitride complex 11, which itself is readily accessible in large quantity from inexpensive sodium molybdate. Complexation of the active silanolate complexes 12 and 24 with 1,10-phenanthroline affords complexes 15 and 25, respectively, which are stable in air for extended periods of time. Although these phenathroline adducts are per se unreactive vis-a-vis alkynes, catalytic activity is conveniently restored upon exposure to MnCl2. Therefore, the practitioner has the choice of different alkyne metathesis (pre)catalysts, which are easy to handle yet broadly applicable and exceedingly tolerant. A host of representative inter- as well as intramolecular alkyne metathesis reactions, including applications to a considerable number of bioactive and, in part, labile natural products, shows the remarkable scope of these new tools. Moreover, it was found that the addition of molecular sieves (5 A ≤ 4 A > 3 A) to the reaction mixture significantly improves the chemical yields while simultaneously increasing the reaction rates. This benefit is ascribed to effective binding of 2-butyne, which is released as the common byproduct in reactions of alkynes bearing a methyl end-cap. Thus, alkyne metatheses can now be performed at ambient temperature with neither the need to apply vacuum to drive the conversion nor recourse to tailor-made substrates. The structures of representative examples of this new generation of alkyne metathesis catalysts in the solid state were determined by X-ray analysis.