Robust Alkyne Metathesis Catalyzed by Air Stable d² Re(V) Alkylidyne Complexes

Abstract

We report in this communication the first example of catalytic alkyne metathesis reactions mediated by well-defined non-d 0 alkylidyne complexes. The air-stable d 2 Re(V) alkylidyne complex Re4, bearing two PO-chelating ligands and a labile pyridine ligand, could catalyze homometathesis of internal alkynes with a broad substrate scope, including alcohols, amines, and even carboxylic acids. The catalyst can tolerate heating, air, and moisture in both solid and solution states, and the catalytic metathesis reactions could proceed normally in wet solvents.

By-design molecular architecturesviaalkyne metathesis

“…1 , structure X ). 35 The catalyst was active for various substrates including carboxylic acids at high temperature under nitrogen. Very recently, Zhang and co-workers developed multidentate tris(2-hydroxyphenyl)methine-based catalysts ( Fig.…”

183W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis

“…Molybdenum alkylidyne complexes endowed with triarylsilanolate ligands such as 1, the corresponding ate-complex 2 and the derived bench-stable phenanthroline adduct [1•-(phen)] set the standards in the field of alkyne metathesis (Figure 1). [1][2][3][4][5] Their functional group compatibility is largely unrivaled; [6][7][8][9][10] it has recently been further improved by the development of a second catalyst generation distinguished by a tripodal silanolate ligand framework. [11,12] Specifically, the "canopy complex" 3 and relatives maintain the virtues of the parent complex 1, yet allow the chelate effect to be harnessed in form of an improved stability towards protic sites; in conjunction with the well-balanced electrophilic character and proper steric protection of the operative Mo CR unit, this results in an excellent overall application profile.…”

Productive Alkyne Metathesis with “Canopy Catalysts” Mandates Pseudorotation

“… 7 − 9 A new generation of “canopy catalysts” of type 2 distinguished by a tripodal silanolate ligand framework shows an even better application profile. 10 − 13 …”