An Efficient and Selective Epoxidation of Olefins with Novel Methyltrioxorhenium/(Fluorous Ponytailed) 2,2′‐Bipyridine Catalysts

Abstract

Novel complexes between methyltrioxorhenium (MTO) and bis(fluorous‐ponytailed) 2,2′‐bipyridines (bpy‐Fn) were synthesized and used for the oxidation of alkenes with hydrogen peroxide under fluorous catalysis. High conversions and yields of the corresponding epoxides were obtained.

Crystal Structure and Catalytic Behavior in Olefin Epoxidation of a One-Dimensional Tungsten Oxide/Bipyridine Hybrid

“…For compounds of the type [Fe­(L)­(CH 3 CN) 2 ]­(ClO 4 ) 2 (L = aminopyridine ligand), the epoxidation of Cy with H 2 O 2 (CH 3 CN as cosolvent) was much faster than that found for 1 , although in the former case a large excess of acetic acid was used to promote the catalytic reaction (Table ) . Complexes of the type [ReO 3 (CH 3 )­L] [L = bis­(fluorous-ponytailed)-2,2′-bipyridines] led to faster reaction of Cy than 1 at 55 °C; however, twice the molar amount of metal was used in the case of the rhenium catalysts, and halogenated cosolvents were used …”

“…With the aim of unambiguously identifying this compound, a large-scale (33-fold increase) experiment was carried out for 1/H 2 O 2 /CH 3 CN (without olefin; please see the Experimental Section for details). After 24 h of reaction at 70°C, the reaction mixture was cooled to ambient temperature and filtered to isolate a (12) 3-octene-2-one (6) 3,4-epoxy-2-octanone (9) 3,4-epoxy-2-octanone (5) 3,5-octadiene-2-ol (6) 3,5-octadiene-2-ol (5) (17) styrene glycol (10) benzaldehyde (43) benzaldehyde (44) benzoic acid (12) benzoic acid ( Figure S7 in the Supporting Information). 48 As will be described below, the complexes [MO(O 2 ) 2 (2,2′-bpy)] (M = Mo, W) are isotypical.…”

“…42 however, twice the molar amount of metal was used in the case of the rhenium catalysts, and halogenated cosolvents were used. 43 Iodometric titrations (ca. 10% error) for the systems 1/ H 2 O 2 /(EtOH or CH 3 CN) heated at 70 °C for 24 h (without olefin) indicated no significant decomposition of the oxidant.…”

Methyltrioxorhenium (MTO) catalysis in the epoxidation of alkenes: a synthetic overview

“…H 2 O 2 in CH 2 Cl 2 under fluorous catalysis (Scheme 19). 44 Different alkenes such as cyclohexene, cyclooctene, trans-stilbene, and styrene were examined and good yields of the epoxides were obtained. Unfortunately, stilbene and styrene epoxides underwent decomposition to afford diols as minor products under all the given catalytic conditions.…”

Dendrimer crown-ether tethered multi-wall carbon nanotubes support methyltrioxorhenium in the selective oxidation of olefins to epoxides

“…15 Crown ethers are coordination sites for methyltrioxorhenium (MTO), 16,17 a potent catalyst for the activation of hydrogen peroxide (H 2 O 2 ) by formation of two reactive intermediates, namely monoperoxo [MeRe(O 2 )O 2 ] and bis(peroxo) [MeRe(O 2 )O 2 ] h2-metal complexes. 18 The chemistry of MTO is largely reviewed, 19 including s C-H oxygen atom insertion 20 and oxy-functionalization, 21 oxidative nucleophilic substitution, 22 oxidative desulfurization (ODS), 23 synthesis of quinone derivatives, 24 Baeyer-Villiger rearrangement, 25 metathesis, 26 methanolysis of glycals, 27 and epoxidation of olens in traditional 28 and non-conventional solvents, such as chiral aliphatic amines, 24 uorinated solvent 29 and ionic liquids. 30 The formation of diols is the major drawback in the epoxidation of olens, as a consequence of the acidic property and high affinity of Re(VII) for the oxygen atom.…”