Redox Isomerization of Allylic Alcohols Catalyzed by New Water-Soluble Rh(I)-N-Heterocyclic Carbene Complexes

Abstract

New water-soluble, N-heterocyclic carbene (NHC) or mixed NHC/tertiary phosphine complexes [RhCl(cod)(sSIMes)], Na2[Rh(bmim)(cod)(mtppts)], and [Rh(bmim)(cod)(pta)]BF4 were synthetized and applied for the first time as catalysts in redox isomerization of allylic alcohols in aqueous media. [RhCl(cod)(sSIMes)] (with added sulfonated triphenylphosphine) and [Rh(bmim)(cod)(pta)]BF4 catalyzed selectively the transformation of allylic alcohols to the corresponding ketones. The highest catalytic activity, TOF = 152 h−1 (TOF = (mol reacted substrate) × (mol catalyst × time)−1) was observed in redox isomerization of hept-1-en-3-ol ([S]/[cat] = 100). The catalysts were reused in the aqueous phase at least three times, with only modest loss of the catalytic activity and selectivity.

Ru complexes containingN‐methyl‐1,3,5‐triaza‐7‐phosphaadamantane (mPTA) as catalysts for the isomerization of 2‐cyclohexen‐1‐ol

“…[3] Among them, secondary allylic alcohols from 1-propen-3-ol to 1-octen-3-ol are easily isomerized by known catalysts. [4][5][6][7][8][9][10][11][12] Nevertheless, isomerization of substituted allylic alcohols, particularly with bulky groups, is scarce or nonexistent. [10] Thus, additional research efforts should be done to determine the influence of substituents on the catalytic isomerization of allylic alcohols, particularly to develop new methods to isomerize natural products containing functionalized allylic alcohol groups.…”

Transformation of the pheromone 3‐methyl‐2‐cyclohexen‐1‐ol in the presence of [RuClCp (PTA)2] and [RuCp (OH2)(PTA)2]CF3SO3

“…Most of them are hydrophilic tertiary phosphines, 9 such as Na-mTPPMS = (3-sulfonatophenyl)diphenylphoshine sodium salt and Na 3 -mTPPTS = tris(3-sulfonatophenyl)phosphine sodium salt, 10,11 and the adamantane-like ligand 1,3,5-triaza-7phosphaadamantane (PTA) [12][13][14] and its derivatives. 10,[12][13][14][15][16][17][18][19] Usually, efficient metal complexes found to be active for the isomerization of allylic alcohols contain transition metals 8,15,16 such as Fe, [17][18][19] Rh, [20][21][22][23][24][25] Ir, [26][27][28] Ni, [29][30][31] Ru, [32][33][34][35][36][37] Co, 38 and Pd. 39 Up to date, several half-sandwich cyclopentadienyl or arene ruthenium complexes that contain ligands such as Na-mTPPMS, 40 PTA, 4,[41][42][43]…”

Insights into the κ-P,N Coordination of 1,3,5-Triaza-7-phosphaadamantane and Derivatives: κ-P,N-Heterometallic Complexes and a 15N Nuclear Magnetic Resonance Survey

“…During the past several years, we have devoted a great deal of effort to synthesizing mono- and polymetallic complexes containing PTA and its derivatives, affording good homogeneous catalysts for the isomerization of allylic alcohols in water 36 − 42 like complex 9 , 43 highly antiproliferative compounds 44 − 47 such as compounds 17–19 , 48 , 49 and heterometallic polymers like 15 built via assembly of dimetallic complex 12 through metallic moieties ( Figure 2 ). 50 The simplest functionalizations of the PTA cage are mono- and bis-N-methylation to afford the cationic ligands N -methyl-PTA (mPTA) ( 5 ) and N , N′ -dimethyl-1,3,5-triaza-7-phosphaadamantane (dmPTA) ( 6 ).…”