Sulfoxidation route

There are two technical routes to the manufacture of alkanesulfonates sulfoxidation and sulfochlorination [1,2]. The sulfoxidation route is the economically more important one, and new plants are based exclusively on this tech-... 

In the homologous series of alkane 1-sulfonates, micellization in aqueous solutions begins with the pentanesulfonate at cM = 1 mol/L. The critical micelle concentrations of the technical alkanesulfonates are cM = 0.002 mol/L (sulfo-chlorination route) and cM = 0.44 g/L (sulfoxidation route). 

The many recent publications affirm the importance of this reaction in modem synthesis. Tanaka and Takemoto s synthesis of the marine metabolite halicholactone uses a sulfoxide route to the allylic alcohol 115. Notice the suprafacial [2,3]-sigmatropic rearrangement and that the OH group ends up in the middle of the diene. Attempted cyclopropanation of 115 gave a poor yield of a mixture of products.21... 

Simple alkyl derivatives of 1 have been reported and studied [56,108-111]. A 1990 patent reports the synthesis of 5-dodecylbenzo[c]thiophene by the sulfoxide route (see Schemes 1 and 2) and its electrochemical polymerization (acetonitrile/Bu4N Cl ) to poly(5-dode-cylbenzo[c]thiophene) (71). The polymer was reported to be soluble in a variety of organic solvents, and an electrochemically doped Him had a four-point probe conductivity of 10 S/cm. Several other alkyl derivatives were said to have been made, and the following conductivities ([Pg.290]

Other monosubstituted polyisothianaphthenes have been reported. In 1989 a report appeared stating that poly(5-benzoyIbenzo[c]thiophene) (80) had been prepared by electrochemical polymerization of the monomer, 5-benzoylbenzo[c]thiophene, which had been prepared by the sulfoxide route similar to that shown in Scheme 1 for the parent polymer 1 and in Scheme 2 [28]. Unfortunately, no other data were given. A variety of other substituted derivatives were prepared by the sulfoxide route (Schemes 1 and 2) as described in a Japanese patent, and four-point probe conductivities (electrochemical doping/Bu4N Cl /CHaCN) of 10 S/cm were reported for poly(5-octyloxybenzo[c]thiophene) (81) and poIy(5-octyIaminobenzo[f]thiophene) (82)... 

Nucleophilic Substitution Route. Commercial synthesis of poly(arylethersulfone)s is accompHshed almost exclusively via the nucleophilic substitution polycondensation route. This synthesis route, discovered at Union Carbide in the early 1960s (3,4), involves reaction of the bisphenol of choice with 4,4 -dichlorodiphenylsulfone in a dipolar aprotic solvent in the presence of an alkaUbase. Examples of dipolar aprotic solvents include A/-methyl-2-pyrrohdinone (NMP), dimethyl acetamide (DMAc), sulfolane, and dimethyl sulfoxide (DMSO). Examples of suitable bases are sodium hydroxide, potassium hydroxide, and potassium carbonate. In the case of polysulfone (PSE) synthesis, the reaction is a two-step process in which the dialkah metal salt of bisphenol A (1) is first formed in situ from bisphenol A [80-05-7] by reaction with the base (eg, two molar equivalents of NaOH),... 

Vinyl Pyrroles. Relatively new synthetic routes based on a one-pot reaction between ketoximes and acetjiene ia an alkaU metal hydroxide—dimethyl sulfoxide (DMSO) system have made vinyl pyrroles accessible. It requires no pyrrole precursors and uses cheap and readily available ketones (42). 

Fluonnation of a sulfoxide-stabilized carbanion provided a route to fluorinated estrones after elimination of the sulfoxide [111] (equation 62). 

Replacement of the terminal nitrogen of the piperazine by carbon is said to enhance the antiemetic activity of the phenothiazines at the expense of the other pharmacologic effects. The simplest compound in this series, pipamazine (88), is prepared by alkylation of nipecotamide (87) with the chloropropyl phenothiazine (58). Preparation of the analogous sulfoxide begins with acetylation of the thiomethyl compound, 89 [prepared by a route... 

Conceptually closely related, cefroxadi ne (40) can be prepared by several routes, including one in which the enol (33) is imethylated with diazomethane as a key step. A rather more involved route starts with comparatively readily available phenoxymethylpenicillin sulfoxide benzhydryl ester (36). This undergoes fragmentation when treated with benzothiazole-2-thiol to give Ozonolysis (reductive work-up) cleaves the... 

On treatment with a strong base such as sodium hydride or sodium amide, dimethyl sulfoxide yields a proton to form the methylsulfinyl carbanion (dimsyl ion), a strongly basic reagent. Reaction of dimsyl ion with triphenylalkylphosphonium halides provides a convenient route to ylides (see Chapter 11, Section III), and with triphenylmethane the reagent affords a high concentration of triphenylmethyl carbanion. Of immediate interest, however, is the nucleophilic reaction of dimsyl ion with aldehydes, ketones, and particularly esters (//). The reaction of dimsyl ion with nonenolizable ketones and... 

The loss of an oxygen atom from the molecular ions of 10 occurs also to some extent and is most pronounced when R = CH3 (route I in equation 2). The predominant fragmentation route of methyl and ethyl 2-hydroxyphenyl sulfoxides is II (equation 2) which, however, is not important when R > Et. Ethyl 2-hydroxyphenyl sulfoxide undergoes also fragmentation via route III, which is the main path of fragmentation when R > Et10. 

Two-component methods represent the most widely applied principles in sulfone syntheses, including C—S bond formation between carbon and RSOz species of nucleophilic, radical or electrophilic character as well as oxidations of thioethers or sulfoxides, and cheletropic reactions of sulfur dioxide. Three-component methods use sulfur dioxide as a binding link in order to connect two carbons by a radical or polar route, or use sulfur trioxide as an electrophilic condensation agent to combine two hydrocarbon moieties by a sulfonyl bridge with elimination of water. 

Route c involves the oxidation of thiiranes through the corresponding sulfoxides to the dioxide stage. The problems associated with this route have been discussed above, and its scope was shown to be rather limited. 

Two attractive routes to thiolene oxide and dioxide are the diene-SO104 and diene-S02298 cycloadditions, respectively. These cycloadditions are highly stereoselective at both carbons of the diene systems and at sulfur (see equation 62 for specifics) which, in the case of sulfoxide formation, proceed via attack of triplet SO on the diene. Equation 112 shows an example of such a cycloaddition104. The overall yields are significantly improved by running the cycloadditions in the absence of oxygen and by the use of excess diene. 

The common route for the synthesis of medium-size ring sulfoxides and sulfones is oxidation of the corresponding cyclic sulfides70, which are obtained from the interaction of a, w-dihaloalkanes with sulfide ion in fair to good yields243 (equation 110). 

Other less general routes to the medium-size ring sulfoxide and sulfone systems do exist, but each one is specific to a particular ring size and to the specifically desired structural features of the target molecule. Equations 131 and 132 are two examples353,354 of such syntheses. 

Owing to the reversible nature of the allylic sulfenate/allylic sulfoxide interconversion, the stereochemical outcome of both processes is treated below in an integrated manner. However, before beginning the discussion of this subject it is important to point out that although the allylic sulfoxide-sulfenate rearrangement is reversible, and although the sulfenate ester is usually in low equilibrium concentration with the isomeric sulfoxide, desulfurization of the sulfenate by thiophilic interception using various nucleophiles, such as thiophenoxide or secondary amines, removes it from equilibrium, and provides a useful route to allylic alcohols (equation 11). 

The data presented demonstrate that allylic sulfoxides can provide an easy and highly stereoselective route to allylic alcohols taking advantage of the facility of the allylic sulfoxide-sulfenate [2,3]-sigmatropic rearrangement. This is of considerable synthetic utility, since a number of stereoselective and useful transformations of allylic alcohols and their derivatives have become available in recent years107-109. 

More recently, another sulfoxide- sulfine photoconversion has been reported by Franck-Neumann and Lohmann223. These authors have shown that the photolysis of allylsulfinylpyrazolenines (167) provides a novel route to vinyl sulfines 168, presumably via ring-opening to a-diazosulfoxides and their a-sulfinylcarbene intermediates (equation 67). 

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