Reactions sulfoxidation

Orga.nic Chemistry. The organic chemistry of sulfur dioxide, particularly as it relates to food appHcations, has been discussed (246). Although no reaction takes place with saturated hydrocarbons at moderate temperatures, the simultaneous passage of sulfur dioxide and oxygen into an alkane in the presence of a free-radical initiator or ultraviolet light affords a sulfonic acid such as hexanesulfonic acid [13595-73-8]. This is the so-called sulfoxidation reaction (247) ... 

NaBH4 is soluble in water, alcohols, pyridine, dioxane, dimethoxyethane, diglyme and triglyme. All these solvents, as well as aqueous tetrahydrofuran and aqueous dimethylformamide, have been used for reductions. The reductions go very slowly in di- and triglyme so these solvents are not suitable for preparative work. In some reductions in dry pyridine and dry dimethyl sulfoxide, reaction only takes place on aqueous work-up. This... 

Addition of Methyl Sulfoxides Reactions with Imines... 

Details of the reaction mechanism and alternatives to the sulfoxidation reaction are described elsewhere [2]. 

Recent studies on isolated BVMOs using Rh-complexes as NADPH substitutes for facile cofactor recycling suggested a pivotal role of the native cofactor to generate the proper environment within chiral induction in sulfoxidation reactions. While biooxidation was still observed in the presence of the metal complex, stereoselectivity of the enzyme was lost almost completely [202]. 

Both the selenoxide and sulfoxide " reactions have been used in a method for the conversion of ketones, aldehydes, and carboxylic esters to their a, P-unsaturated derivatives (illustrated for the selenoxide). 

Sumiyoshi and coworkers suggested that the reaction of OH radical with the sulfoxides S— bond can be studied by looking for the sulfmic acid which is expected from the reaction of OH radical and a sulfoxide (reaction 24). 

Complex 24 catalyzes this reaction, although the process occurs much more slowly than does Eq. (38). An extensive set of kinetic data lead to the mechanism presented in Scheme 15. It features two sequential sulfoxide reactions, one to form dioxorhenium(VII), the next to reconvert it to 24. 

Dembitsky, M.V., Oxidation, epoxidation and sulfoxidation reactions catalysed by haloperox-idases. Tetrahedron, 2003, 59, 4701. 

In addition to the activity of the protein in substrate processing, stereospecificity of substrate oxidation is of equal concern. As a result, studies of Mb monooxygenase activity are frequently complemented by determination of the enantiomeric ratio of products (enantiomeric excess) and analysis of the fraction of peroxide oxygen transferred to product. As epoxidation and sulfoxidation reactions catalyzed by Mb have received particular attention, the following discussion considers the progress in understanding these activities of both wild-type and variant forms of the protein. 

Sulfoxidation reactions are characterized by enzymatic conversion of a divalent compound to sulfoxide (Fig. 15.7) or, in some cases, to sulfone (S SO O ). The degradation also may be catalyzed by minerals, converting organic sulfides (thioesters) and sulfites to the corresponding sulfoxides and sulfates. Because it is difficult to determine if the reaction is chemically or biologically induced, microbially mediated sulfoxidation in the subsurface environment can be established only when a biocatalyst is found. 

A new enantiopure, bidentate ligand (35, 45 )-2,2,5,5-tetramethyl-3,4-hexanediol [(35, 45)-186] was developed by Yamanoi and Imamoto and investigated as asymmetric inductor in the titanium-catalyzed sulfoxidation reaction with various hydroperoxides as oxygen donors (Scheme 107). The catalytically active species was then prepared in situ from Ti(OPr-/)4 and ligand (35,45)-186. The most efficient hydroperoxide in terms of enantio-selectivity turned out to be cumyl hydroperoxide (95% ee compared to 30% ee in the case of methyl p-tolyl hydroperoxide), and molecular sieves 4 A had a beneficial effect on the... 

The hydroperoxide from the more acidic fluorene prefers to react via the decomposition process (Reaction 6 or 7) rather than the reductive reaction with dimethyl sulfoxide (Reaction 3). 

Thiophene, diphenylsulfide, diphenyldisulfide, and the disulfides 423 and 424 have been found to be inert in the sulfoxidation reaction.277 However, the production of the sulfoxide 426 from trimethylene disulfide (425) was reported by Calvin and co-workers278 as a result of irradiation of 425 in the presence of oxygen and Zn-tetraphenylporphin. 

The gold solid [RuC CHsSOCeHs ln, isolated from the methyl phenyl sulfoxide reaction, is diamagnetic or feebly paramagnetic and shows a S-bonded y(SO) at 1130 cm-1 and i/(Ru-Cl) at 330 cm-1. The limited solubility suggests a polymeric structure. 

For the most pan, sulfoxides are crystalline, colorless substances, although the lower aliphatic sulfoxides melt at relatively low temperatures. The lower aliphatic sulfoxides are water soluble but as a class the sulfoxides are not soluble in water. They are soluble in dilute acids and a few are soluble in alkaline solution. DMSO is a colorless liquid selected properties are listed in Table 1. Dimethyl sulfoxide generally undergoes typical sulfoxide reactions. It is used herein as an illustrative example. 

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