Mononuclear Ruthenium Catalysts for the Direct Propargylation of Heterocycles with Propargyl Alcohols

Abstract

A new family of mononuclear ruthenium catalysts for the catalytic direct propargylation by propargylic alcohols of heterocycles is presented. The catalyst activity can be improved by tuning the ligands influence and electronic properties at the metal centre. Whereas [(p-cymene)

Activation of Mononuclear Arene Ruthenium Complexes for Catalytic Propargylation Directly with Propargyl Alcohols

“…[10] Additionally, the internal propargyl alcohol 1,3-diphenyl-2-propynol, PhC CCH(OH)Ph (1e), has been reacted with furan and 2-methylfuran at 60 8C in acetone in the presence of 5 mol % of the preactivated complex 7a (! [8a]), affording the corresponding propargylated product PhC CCH(R)Ph [R = C 4 H 3 O (4d), C 4 H 2 O-CH 3 (4e)] in 31 % and 25 % isolated yields, respectively ( Table 1, entries 8 and 9).…”

“…[4] The first examples of mononuclear ruthenium catalysts were simultaneously reported by Gimeno et al [9] and the Rennes group. [10,11] The catalyst precursors…”

“…Complexes 6a and 6b were obtained as described by Werner et al, [21] but using AgOTf as chloride abstractor. The formation of compounds 5a, 5b, 6a and 6b, observed by low temperature [ 10] NMR spectra were recorded on Bruker AM 3000 WB and DPX 200 spectrometers in deuterated solvents. Elemental analysis and high resolution mass spectrometry were performed by the Centre RØgional de Mesures Physiques de l'Ouest, UniversitØ de Rennes 1.…”

Metal Vinylidenes and Allenylidenes in Catalysis: Applications in Anti‐Markovnikov Additions to Terminal Alkynes and Alkene Metathesis

“…We also recently reported the first propargylation of furans catalyzed by the mononuclear ruthenium complexes [RuCl(PR 3 )(p-cymene)]OTf (R = Ph, Cy) (Scheme 55). [232] A study of the catalytic precursor, but with the B(Ar F ) 4 À anion, showed that the two primary products, the ruthenium allenylidene complex and water, which arises from dehydration of the propargylic alcohol, react by addition at Ca to form a stable vinylic hydroxycarbene ruthenium intermediate, which upon heating at above 50 8C evolves into the carbonyl cationic species [RuCl(PCy 3 )(CO)(p-cymene)] + . [232] This complex exhibits good catalytic activity for the propScheme 51.…”

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

“…Based on these preliminary results, various catalytic propargylations of arenes have been developed, employing catalysts such as Mo/chloranil [16], polymolybdophosphoric acid supported silica [99], TsOH [100], FeCl 3 [101–102], BiCl 3 [103], Sc(OTf) 3 [104] other Ru- or [105–107], Re-complexes [108] and even molecular iodine [109]. …”