Remarkable increase in the rate of the catalytic epoxidation of electron deficient styrenes through the addition of Sc(OTf)₃ to the MnTMTACN catalyst

Abstract

The effect of Lewis acids on the catalytic activity of [Mn(μ-O)(TMTACN)](PF) in the epoxidation of styrenes using hydrogen peroxide as the oxidant has shown that the addition of Sc(OTf) at low catalytic loading results in a very significant increase in the efficiency of the catalyst and a reduction of the reaction time to only 3 minutes in most cases.

Unprecedented Asymmetric Epoxidation of Isolated Carbon–Carbon Double Bonds by a Chiral Fluorous Fe(III) Salen Complex: Exploiting Fluorophilic Effect for Catalyst Design

“…Although the use of electron rich olefins as the substrate tended to provide higher reactivity, the tendency was hard to declare with respect to the enantioselectivity (Entries 5-8). To investigate whether the reaction proceeds via radical species or a concerted mechanism, a radical clock experiment [22] using cyclopropane compound 14 [23] and catalyst 3e was conducted ( Figure 4). This experiment revealed that the reaction proceeds via a radical mechanism if the cyclopropane-ringopened product 18 is obtained.…”

“…Radical clock experiment. [23] oxidizing reagent screening (Table 2), aerobic oxidation conditions afforded a dramatically lower stereoselectivity than hypervalent iodine conditions (Entry 4 vs. Entry 1).…”

Green Procedure for One-Pot Synthesis of Azelaic Acid Derivatives Using Metal Catalysis

“…Starting from the first example regarding catalytic ability of Yb(OTf) 3 , many processes proved to be promoted by these metals in aqueous media [27]. More recently, Scandium(III) and Ytterbium(III) triflates have been used as cocatalysts of Mn complexes in the epoxidation of styrene [12]. To date, none of them have been employed in the oxidation of unsaturated fatty acids.…”

“…Recently, Molybdenum and some rare earth derivatives (Sc and Yb), by their Lewis acid properties, displayed interesting activity in the oxidation of olefins [10][11][12], therefore, we planned their involvement in the oxidation of oleic acid 1 and corresponding methyl ester 1a, to replace the noneco-friendly and unrecyclable HBF 4 and H 3 PO 4 .…”

Generation and Electron‐Transfer Reactivity of the Long‐Lived Photoexcited State of a Manganese(IV)‐Oxo‐Scandium Nitrate Complex

“…Binding of redox-inactive metal ions including Ca 2 + ion to the oxo moiety of high-valent manganese(IV)-oxo complexes is reported to result in enhancement of the redox reactivity. [8][9][10][11][12][13][14][15][16] Photoexcitation of a Mn IV -oxo complex binding two scandium ions, [(Bn-TPEN) Mn IV (O)] 2 + À (Sc(OTf) 3 ) 2 (Bn-TPEN = N-benzyl-N,N',N'-tris (2-pyridylmethyl)-1,2-diaminoethane) [12] is also reported to result in the formation of a long-lived photoexcited state with a lifetime of 6.4 μs, which exhibits high redox reactivity, capable of hydroxylating benzene with water to produce phenol. [17] Generation of such long-lived photoexcited state of a manganese(IV)-oxo complex provides an excellent photooxidant for oxidation of organic substrates.…”