Sulfones ether transfer

Because the key chloromethyl intermediate can be trapped efficiently by thiophenol, 2-sulfonylpyrans 96 are readily available. Ether transfer followed by a thiophenol quench and oxidation provides sulfone 95 in excellent yield and high stereoselectivity. Analogous to the nitrile, the presence of the sulfone functionality provides an opportunity for cyclization through deprotonation of an a-proton (Scheme 37.23). 

Ley et al. previously demonstrated the synthetic value of 2-sulfonylpyrans for the synthesis of 2,6-cis and 2,6-tra 5-tetrahydropyran. These more complex systems resulting from the ether transfer contain oxidation and the 4-position common to many polyketides. Conversion of intermediate sulfone 96 into 4-methoxy-2,6-tra/Js-tetrahydropyran 97 was accomplished by direct ionization of the sulfone in the presence of aluminum trichloride and a nucleophile (Scheme 37.24). ... 

The a -halosulfone, required for the Ramberg-Backlund reaction, can for example be prepared from a sulfide by reaction with thionyl chloride (or with N-chlorosuccinimide) to give an a-chlorosulfide, followed by oxidation to the sulfone—e.g. using m-chloroperbenzoic acid. As base for the Ramberg-Backlund reaction have been used alkoxides—e.g. potassium t-butoxide in an etheral solvent, as well as aqueous alkali hydroxide. In the latter case the use of a phase-transfer catalyst may be of advantage. ... 

These thiohydroxamic esters have seen use in grafting of PAN onto PE,iM of PS, PAM and I MPAM onto cellulose127128 and of PS, PMMA, PVP and PAM onto poly(arylene ether sulfone).12 7 The process involves derivitization of a parent carboxy functional polymer to form the thiohydoxamic ester 82 (R=polvmcr) which then behaves as a polymeric transfer agent and/or radical generator. 

Finally, the reaction of 19b with potassium fluoride in the presence of a crown-ether phase-transfer agent118 to yield the sulfonyl fluoride 67 and diphenylacetylene119 belongs to the same category in which a nucleophile (F in this case) attacks the electrophilic sulfur of the sulfone group (equation 19). 

A polymeric composition for reducing fluid loss in drilling muds and well cement compositions is obtained by the free radical-initiated polymerization of a water-soluble vinyl monomer in an aqueous suspension of lignin, modified lignins, lignite, brown coal, and modified brown coal [705,1847]. The vinyl monomers can be methacrylic acid, methacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, vinylacetate, methyl vinyl ether, ethyl vinyl ether, N-methylmethacrylamide, N,N-dimethylmethacrylamide, vinyl sulfonate, and additional AMPS. In this process a grafting process to the coals by chain transfer may occur. 

Several microwave-assisted protocols for soluble polymer-supported syntheses have been described. Among the first examples of so-called liquid-phase synthesis were aqueous Suzuki couplings. Schotten and coworkers presented the use of polyethylene glycol (PEG)-bound aryl halides and sulfonates in these palladium-catalyzed cross-couplings [70]. The authors demonstrated that no additional phase-transfer catalyst (PTC) is needed when the PEG-bound electrophiles are coupled with appropriate aryl boronic acids. The polymer-bound substrates were coupled with 1.2 equivalents of the boronic acids in water under short-term microwave irradiation in sealed vessels in a domestic microwave oven (Scheme 7.62). Work-up involved precipitation of the polymer-bound biaryl from a suitable organic solvent with diethyl ether. Water and insoluble impurities need to be removed prior to precipitation in order to achieve high recoveries of the products. 

As mentioned in the Introduction, this chapter focuses on reactions that deliver allenes as the product. The principles discussed in Sections 1.2.1-1.2.9, of course, also allow the synthesis of allenes as reactive intermediates, which due to other functional groups that are present, undergo further reactions in situ. The most important examples here are base-catalyzed isomerizations to furans [347, 348] ring transfer reactions of propargylic ethers or amines [216, 349-371] and enyneallene cycliza-tion reactions starting from propargylic sulfones [372-375] and related substrates [376, 377]. Details are discussed, for example, in Chapters 16 and 20. 

Nafion is a copolymer of poly(tetrafluoroethylene) and polysulfonyl fluoride vinyl ether. It has fixed anions, which are sulfonic acid sites, and consequently, by electroneutrality, the concentration of positive ions is fixed. Furthermore, the transference number of protons in this system is 1, which greatly simplifies the governing transport equations, as seen below. There can be different forms of Nafion in terms of the positive counterion (e.g., proton, sodium, etc.). Most models deal only with the proton or acid form of Nafion, which is the most common form used in polymer-electrolyte fuel cells due to its high proton conductivity. 

Reduction of dibenzothiophene with sodium in liquid ammonia has been shown to be sensitive to the experimental methods employed however, the major product is usually 1,4-dihydrodibenzothiophene. 27 -28i The electrochemical reduction of dibenzothiophene in ethylene-diamine-lithium chloride solution has been shown to proceed via stepwise reduction of the aromatic nucleus followed by sulfur elimination. In contrast to the reduction of dibenzothiophene with sodium in liquid ammonia, lithium in ethylenediamine, or calcium hexamine in ether, electrolytic reduction produced no detectable thiophenol intermediates. Reduction of dibenzothiophene with calcium hexamine furnished o-cyclohexylthiophenol as the major product (77%). Polaro-graphic reduction of dibenzothiophene 5,5-dioxide has shown a four-electron transfer to occur corresponding to reduction of the sulfone group and a further site. ... 

A number of solvent extraction experiments have demonstrated that individual crown ethers in combination with a lipophilic sulfonic acid (such as didodecylnaphthalene sulfonic acid) are efficient, synergistic phase transfer agents for manganese(II) from aqueous solution into an organic phase." The X-ray structure of the manganese di-t-butylnaphthalenesul-fonate with cyclohexano-15-crown-5 ether as its toluene solvate has been reported." ... 

Chiral derivatives of hemiacetal from fluoral have been prepared by adding an alcohol to fluoral in the presence of (l )-BlNOL— Ti(0—iPr)2 or by HPLC resolution of the racemate. The displacement of the sulfonate moiety from the tosyl derivative, by an alkyl lithium aluminate, affords the trifluoromethyl ether with inversion of configuration and an excellent chirality transfer (Figure 2.49). ° ... 

In some cases where bridged dianhydrides were used, four signals were observed in NMP, evidently because of the ability to transfer K-electron density through such bonds as ether, sulfone, or ketone as discussed above. As an example of such behavior, the diamic acid isomeric solution based on l,l -bis(3,4-carboxyphenyl)sulfone dianhydride (SDA) displayed the spectrum illustrated in... 

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