Palladium-catalysed cross-coupling reactions in supercritical carbon dioxide

Abstract

Heck and Suzuki reactions proceed in good yield in supercritical carbon dioxide in the presence of palladium acetate and tri-tert-butylphosphine with both free and polymer-tethered substrates.

Mizoroki–Heck Reactions: Modern Solvent Systems and Reaction Techniques

“…In addition to those improvements by using fluorinated ligands, nonfluorinated systems (palladium acetate with tri-tert-butylphosphane) also yield coupling products in up to 98% yield starting from 5 (X = I) and (free and polymer-tethered) acrylates [110]. Further optimization of reagent systems could even suppress unwanted isomerization of double bonds in intramolecular Mizoroki-Heck reactions (Scheme 15.11).…”

Organotin Reagents in Cross‐Coupling Reactions

“…The complex is air stable and soluble in water, which facilitates product isolation [17]. Supercritical carbon dioxide has been used in palladium-catalyzed cross-coupling reactions [18]. For example, for aryl iodides and vinyltins [18b], the best ligand tested was tris[3,5-bis(trifluoromethyl)phenyl]phosphine, which gave conversions up to 99%.…”

CC Bond‐Forming Reactions

“…Palladium trifluoroacetate (10 mol %) in conjunction with DIPEA gave the highest yields at only 40°C. Aryl bromides gave somewhat lower yields than aryl iodides [42].…”

“…This provides a potential means of performing these reactions on an industrial scale in a more environmentally benign way in high yields [40]. Pd salts together with polyfluorinated phosphine ligands [41] or t-Bu 3 P [42] were found beneficial. The main drawback of this method is the necessity for high pressure, which requires presently non-standard equipment.…”