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Vinylsulfonium salts

The intramolecular addition of sulfur ylides to imines (e.g. 72) has proven to be an excellent route to fused-ring aziridines (e.g. 73) <06AG(I)7066>. The addition of a sulfonamide to a vinylsulfonium salt leads to the formation of the sulfur ylide 72. The ylide then undergoes an intramolecular addition to form the product fused-ring aziridine 73. This method has also been used for the synthesis of fused-ring epoxides. [Pg.83]

The most functionalized mitomycin precursor was synthesized by Dong and Jeminez <1999JOC2520> in a racemic form, starting from indolic anion 266 and vinylsulfonium salts (route a) they also explored a diastereoselective version of this synthesis by using enantiopure vinylsulfonium salts, which gave low asymmetric induction <2001TA999>. [Pg.34]

Both the lack of regioselectivity observed for the intramolecular insertion of alkylidene carbenes derived from (E)- and (Z)-A -iodanes 108 and the high degree of stereo convergence of the olefin geometry of vinylsulfonium salts indicate the intermediacy of the free alkylidene carbene [Eq. (99)] [53,172]. [Pg.50]

A variety of a,jS-unsaturated esters and nitriles bearing a leaving group at the a-carbon" ", vinyl selenones" ", vinylsulfoxonium salts" and vinylsulfonium salts" "" have been found to react with doubly activated methylene compounds, such as... [Pg.341]

Asymmetric induction has been accomplished with the use of optically active vinylsulfonium salts with asymmetry at sulfur (equation 94)" Less acidic methylene... [Pg.341]

Table 25. Synthesis of Electrophilic Cyclopropanes Using Vinylsulfonium Salts... Table 25. Synthesis of Electrophilic Cyclopropanes Using Vinylsulfonium Salts...
The most widely explored method is the formation of tri- and tetrasubstituted cyclopropanes by reaction of vinylsulfonium salts with methylene compounds activated by ester, ketone, nitrile, or sulfone substituents. A series of examples is collected in Table 25. A variant of this method, where cyclopropanedicarboxylates cis-1 were actually obtained by intramolecular cyclization of the sulfonium salt Cj building block is also shown.Alkylthiocyclopropane derivatives 8 were obtained by the reaction of a ketene dithioacetal monosulfonium salt with carbanions derived from doubly activated methylene compounds. ... [Pg.95]

Vinylsulfonium salts serve as an electron-deficient alkene and conjugate addition to the alkene generates sulfonium ylides. Thus, conjugate addition to vinylsulfonium compounds provides another preparation of cyclopropanes. For... [Pg.8]

Compounds containing a pyramidally arranged (hence, chiral) sulfur to which are linked three alkyl or aryl groups, resulting in a net positive charge on the sulfur. A biologically important example is S-adenosyl-L-methi-onine chloride. Sulfonium salts can also be utilized as analogs or mimics of carbocation intermediates in enzyme-catalyzed reactions. For example, methyl-(4-meth-ylpent-3-en-l-yl)vinylsulfonium perchlorate proved to be an excellent inhibitor (Ki = 2.5 tM) of the enzyme that catalyzes the formation of the bicyclic (+)- -pinene ... [Pg.666]


See other pages where Vinylsulfonium salts is mentioned: [Pg.29]    [Pg.341]    [Pg.1373]    [Pg.64]    [Pg.8]    [Pg.237]    [Pg.273]    [Pg.467]    [Pg.29]    [Pg.341]    [Pg.1373]    [Pg.64]    [Pg.8]    [Pg.237]    [Pg.273]    [Pg.467]    [Pg.341]    [Pg.53]   
See also in sourсe #XX -- [ Pg.50 ]




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