First Examples of Rhenium-Assisted Activation of Propargyl Alcohols:  Allenylidene, Carbene, and Vinylidene Rhenium(I) Complexes

Abstract

The complex [(triphos)(CO)2Re(OTf)] (1) reacts with disubstituted propargyl alcohols HC⋮CCR(R‘)OH in CH2Cl2 at room temperature (R = R‘ = Ph, Me; R = Ph, R‘ = Me), to give either allenylidene derivatives [(triphos)(CO)2Re{CCC(R)Ph}]OTf (R = Ph, 2; R = Me, 3) or the dinuclear vinylidene−carbene complex [{(triphos)(CO)2Re}2{μ-(C10H12)}](OTf)2 (5) (R = R‘ = Me) (triphos = MeC(CH2PPh2)3; OTf = CF3SO3 -). The secondary propargyl alcohol HC⋮CCH(Me)OH reacts with 1 in the presence of methanol to give the methoxyalkenyl Fischer-type carbene [(triphos)(CO)2Re{C(OMe)-CHCHMe}]OTf (11). Compound 11 has been authenticated by an X-ray diffraction analysis. The structure of this complex shows the metal center to be surrounded by a fac triphos ligand, by two mutually cis carbonyl groups, and by the organyl ligand in a slightly distorted octahedral geometry. The reaction with HC⋮CCH2OH results in the double addition of methanol to give the carbene complex [(triphos)(CO)2Re{C(OMe)(CH2CH2OMe)}]OTf (9). When the reaction between 1 and propargyl alcohol is carried out in the dichloromethane dinuclear vinylidene−carbene complex, [{(triphos)(CO)2Re}2{μ-(C6H6O)}](OTf)2 (10) is obtained.

Recent Developments in the Reactivity of Allenylidene and Cumulenylidene Complexes

“…This fact is clearly shown in the formation of the Fischer‐type carbene complexes [Ru{=C(OMe)−C(H)=C(H)R}(η 5 ‐C 9 H 7 )L 1 L 2 ][PF 6 ] (R = Ph, L 1 L 2 = DPPE, DPPM; R = H, L 1 L 2 = DPPM) which are readily obtained by the reaction of [RuCl(η 5 ‐C 9 H 7 )L 1 L 2 ] with HC≡CCH(OH)R and NaPF 6 in methanol by nucleophilic attack of the alcohol on the unstable allenylidene intermediates [Ru{=C=C=C(H)R}(η 5 ‐C 9 H 7 )L 1 L 2 ][PF 6 ] 41. The related methoxycarbene derivatives [Ru{=C(OMe)−C(H)= CMe 2 }(η 6 ‐C 6 Me 6 )(MDMPP P,O )][PF 6 ][MDMPP‐ P , O = P(2 O ‐6‐MeOC 6 H 3 )Ph 2 ],45 [RuCl{=C(OMe)−C(H)=CPh 2 }(PPh 3 ){κ 3 ‐ N , N , N (PYBOX)}][PF 6 ] [PYBOX = 2,6‐bis(dihydrooxazolin‐2′‐yl)pyridine],16 and [Re{=C(OMe)−C(H)=C(H)Me}(TRIPHOS)(CO) 2 ][CF 3 SO 3 ] [TRIPHOS = 1,1,1‐tris(diphenylphosphanylmethyl)ethane]46 have recently been obtained following this simple synthetic procedure. In addition, the methoxy(methoxyethyl)carbene complex [Re{=C(OMe)CH 2 CH 2 (OMe)}(TRIPHOS)(CO) 2 ][CF 3 SO 3 ] has been prepared by treatment of hydroxyvinylidene [Re{=C=C(H)CH 2 (OH)}(TRIPHOS)(CO) 2 ][CF 3 SO 3 ] with methanol, through a concerted dehydration followed by a double addition of MeOH to the C α and C γ atoms of the transient allenylidene [Re(=C=C=CH 2 )(TRIPHOS)(CO) 2 ][CF 3 SO 3 ] 46…”

“…The related methoxycarbene derivatives [Ru{=C(OMe)−C(H)= CMe 2 }(η 6 ‐C 6 Me 6 )(MDMPP P,O )][PF 6 ][MDMPP‐ P , O = P(2 O ‐6‐MeOC 6 H 3 )Ph 2 ],45 [RuCl{=C(OMe)−C(H)=CPh 2 }(PPh 3 ){κ 3 ‐ N , N , N (PYBOX)}][PF 6 ] [PYBOX = 2,6‐bis(dihydrooxazolin‐2′‐yl)pyridine],16 and [Re{=C(OMe)−C(H)=C(H)Me}(TRIPHOS)(CO) 2 ][CF 3 SO 3 ] [TRIPHOS = 1,1,1‐tris(diphenylphosphanylmethyl)ethane]46 have recently been obtained following this simple synthetic procedure. In addition, the methoxy(methoxyethyl)carbene complex [Re{=C(OMe)CH 2 CH 2 (OMe)}(TRIPHOS)(CO) 2 ][CF 3 SO 3 ] has been prepared by treatment of hydroxyvinylidene [Re{=C=C(H)CH 2 (OH)}(TRIPHOS)(CO) 2 ][CF 3 SO 3 ] with methanol, through a concerted dehydration followed by a double addition of MeOH to the C α and C γ atoms of the transient allenylidene [Re(=C=C=CH 2 )(TRIPHOS)(CO) 2 ][CF 3 SO 3 ] 46…”

Synthesis and Structural Characterization of a Series of New Chiral‐at‐Metal Ruthenium Allenylidene Complexes

“…Since then, a variety of allenylidene complexes have been synthesized and characterized. The majority of allenylidene complexes are based on ruthenium,4 but other metals have been used as well, for example, Cr and W,5a Mo,5b Mn,2b Re,5c Ir,5d Rh,1f Fe,5e Os,5f,5g Pd,5h,5i and Ni 6…”

Polydentate phosphines

“…Other complexes 2-8 (Scheme 15) were synthesized and analyzed by X-ray and NMR spectroscopy [45][46][47].…”