52881-58-0

Upstream product

• 1193-80-2 α-deuteriostyrene 
• 100-42-5 styrene 
• 70-11-1 α-bromoacetophenone 
• 96-09-3 styrene oxide 

Downstream Products

• 129218-76-4 2-phenylthiirane-2-d 
• 60507-03-1 acetophenone-d1 
• 98-86-2 acetophenone 
• 129218-77-5 2-phenylthiirane 1-oxide-2-d 

Relevant academic research and scientific papers

Synthesis of Cyclic Organic Carbonates Using Atmospheric Pressure CO2 and Charge-Containing Thiourea Catalysts

Cycloadditions of epoxides with CO2 to synthesize cyclic five-membered ring organic carbonates are of broad interest from a synthetic, environmental, and green chemistry perspective, and the development of effective catalysts for these transformations is an ongoing challenge. A series of eight charge-containing thiourea salts that catalyze these reactions under mild conditions (i.e., 60 °C and atmospheric CO2 pressure) are reported. Substrate scope and mechanistic studies were also carried out, isotope effects were measured, and a reactive intermediate was isolated revealing a surprising pathway in which a thiourea catalyst serves as a nucleophile in the cleavage of the epoxide ring.

Biomimetic iron-catalyzed asymmetric epoxidation of aromatic alkenes by using hydrogen peroxide

A novel and general biomimetic non-heme Fe-catalyzed asymmetric epoxidation of aromatic alkenes by using hydrogen peroxide is reported herein. The catalyst consists of ferric chloride hexahydrate (FeCl3·OH 2O), pyridine-2,6-dicarboxylic acid (H2-(pydic)), and readily accessible chiral N-arenesulfonyl-N′-benzyl-substituted ethylenediamine ligands. The asymmetric epoxidation of styrenes with this system gave high conversions but poor enantiomeric excesses (ee), whereas larger alkenes gave high conversions and ee values. For the epoxidation of trans-stilbene (1a), the ligands (S,S)-N-(4-toluenesulfonyl)-1,2- diphenylethylenediamine ((S,S)-4a) and its N′-benzylated derivative ((S,S)-5a) gave opposite enantiomers of trans-stilbene oxide, that is, (S,S)-2a and (R,R)-2a, respectively. The enantioselectivity of alkene epoxidation is controlled by steric and electronic factors, although steric effects are more dominant. Preliminary mechanistic studies suggest the in situ formation of several chiral Fe-complexes, such as [FeCl(L*)2-(pydic)] ·HCl (L* = (S,S)-4a or (S,S)-5a in the catalyst mixture), which were identified by ESIMS. A UV/Vis study of the catalyst mixture, which consisted of FeCl3·6H2O, H2(pydic), and (S,S)-4a, suggested the formation of a new species with an absorbance peak at λ = 465 nm upon treatment with hydrogen peroxide. With the aid of two independent spin traps, we could confirm by EPR spectroscopy that the reaction proceeds via radical intermediates. Kinetic studies with deuterated styrenes showed inverse secondary kinetic isotope effects, with values of k H/kD = 0.93 for the β carbon and kH/k D=0.97 for the a carbon, which suggested an unsymmetrical transition state with stepwise O transfer. Competitive epoxidation of para-substituted styrenes revealed a linear dual-parameter Hammett plot with a slope of 1.00. Under standard conditions, epoxidation of la in the presence of ten equivalents of H218O resulted in an absence of the isotopic label in (S,S)-2a. A positive non-linear effect was observed during the epoxidation of la in the presence of (S,S)-5a and (R,R)-5a.

Mechanistic Investigation of the Oxidation of Aromatic Alkenes by Monooxoruthenium(IV). Asymmetric Alkene Epoxidation by Chiral Monooxoruthenium(IV) Complexes

The oxoruthenium(IV) complexes [RuIV(terpy)(6,6′-Cl2-bpy)O](ClO4) 2 (1a; terpy = 2,2′:6′,2″-terpyridine; 6,6′-Cl2-bpy = 6,6′-dichloro-2,2′-bipyridine), [RuIV(terpy)(tmeda)O](ClO4)2 (lb; tmeda = N,N,N′,N′-tetramethylethylenediamine), tRuIV(Cn)(bpy)O](ClO4)2 (1c; Cn = l,4,7-trimethyl-l,4,7-triazacyclononane), and [RuIV(PPz*Xbpy)O](ClO4)2 (Id; PPz* = 2,6-bis[(4S,7A)-7,8,8-trimethyl4,5,6,7-tetrahydro-4,7-methanoindazol-2-yl] pyridine) are effective for the epoxidation of aromatic alkenes in acetonitrile at ambient conditions. Their reactions with c/s-alkenes such as cis-β-methylstyrene and cis-β-deuteriostyrene afford epoxides nonstereospecifically. The observation of the inverse secondary kinetic isotope effect for the β-d2-styrene oxidations [kH/kD -0.87 (1b), 0.86 (Id)], but not for α-deuteriostyrene (kH/kD = 0.98 for lb and Id), indicates that C-O bond formation is more advanced at the β-carbon atom than at the a carbon, i.e., a stepwise mechanism. The second-order rate constants (k2) for the styrene oxidations are weakly dependent on the E°(RuIV/III) values of the oxoruthenium(IV) complexes, and both electron-withdrawing and -donating para substituents mildly accelerate the oxidation reaction of styrene. These findings discount strongly the intermediaries of an alkene-derived cation radical and a carbocation. A linear free-energy relationship between the second-order rate constants for the para-substituted styrene oxidations and the total substituent effect (TE) parameters has been established: (TE) = +0.43 (R = 0.99) for 1b, +0.50 (R = 0.98) for 1c, and +0.37 (R = 0.99) for Id (Wu, Y.-D.; Wong, C.-L.; Chan, K. W.; Ji, G.-Z.; Jiang, X.-K. J. Org. Chem. 1996, 61, 746). This suggests that the oxidation of aromatic alkenes by oxoruthenium(IV) complexes should proceed via the rate-limiting formation of a benzylic radical intermediate. Oxidation of styrene and cis- and trans-β-methylstyrenes by the chiral oxoruthenium (IV) complex Id attains moderate enantioselectivities, in which the production of cis-epoxide is more enantioselective than the trans counterpart. The ligand dissymmetry of PPz* together with the bipyridine ligand create a "chiral pocket" around the RuIV=O moiety, leading to enantiofacial discrimination through nonbonding interaction. Because the acyclic benzylic radical intermediate would undergo cis-trans isomerization before the second C-O bond formation, the overall product enantioselectivity (% eeobs) cannot be determined exclusively by facial selectivity (eefacial) of the first irreversible C-O bond formation step. The extent of the isomerization, measured by the cis-trans-epoxide selectivity or diastereoselectivity of epoxide ring closure, is an important element in controlling the enantiomeric excess of the epoxides.

Novel (α,β-Epoxyalkyl)lithium Reagents via the Lithiation of Organyl-Substituted Epoxides

A series of epoxides bearing unsaturated organyl groups attached directly to the epoxy group was found to have sufficient kinetic acidity to undergo clean lithiation at low temperatures.Epoxides of the type is aryl, vinylic, acetylenic, alkoxycarbonyl, or cyano, were smoothly converted into by either t-BuLi or LDA in the temperature range of -80 to -115 deg C.The resulting (α,β-epoxyalkyl)lithium reagents could be transformed into a variety of substituted epoxides, such as R2C-CE(Un)-O, where E = D, R3Si, R3Sn, R, RCO, CO2H, or COH(R)2.In cases where Un is acyl, addition to the carbonyl, rather than lithiation, occurred preferentially.Attempted lithiations of aziridines and thiiranes led to extrusion of nitrogen and sulfur, respectively.Even the relatively stable intermediates generated at -90 deg C underwent carbenoid-like decomposition at higher temperatures to yield isomerization and intermolecular-insertion products.Observation of these processes gives direct corroboration of reaction mechanisms proposed for the base-promoted isomerizations of epoxides.