New access to long-chain polyketides and spiroketals by umpolung of electron rich dienes with sulfur dioxide
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The reactivity of (E)- and (Z)-1-fluorobuta-1,3-diene ((E)- and (Z)-11), 2-fluorobutadiene (12). (E)and (Z)-1-(fluoromethylidene)-2-methylidenecyclohexane ((E)- and (Z)-13) toward SO2 has been explored and compared with that of (Z)- and (E)-1-(fluoromethyl ...
The reactivity of sulfur dioxide toward variously substituted butadienes was explored in an effort to define the factors affecting the competition between the hetero-Diels-Alder and cheletropic additions. At low temperature (< -70degrees), 1-alkyl-substitu ...
The hetero-Diels-Alder addition of sulfur dioxide to (E)- and (Z)-4-(fluoromethylidene)-3-methylene-2,3-dihydro-naphthalene follows the endo Alder rule. The first example of a crystalline sultine has been obtained. In agreement with high level quantum calc ...
Selective dissolution of titanium through a laser patterned oxide film has been achieved in a 3M sulfuric acid-methanol electrolyte. The 250 nm thick oxide film was formed anodically on a flat titanium surface in 0.5 M sulfuric acid. The patterning of the ...
Chloroprene (= 2-chlorobuta-1,3-diene; 4b) and electron-rich dienes such as 2-methoxy-(4c), 2-acetoxy(dd), and 2-(phenylseleno)buta-1,3-diene (4e) refused to equilibrate with the corresponding sultines 5 or 6 between -80 and -10degrees in the presence of e ...
[Pt-3(mu-CO)(3)(PPh3)(3)] was prepared in high yield by the reaction of [Pt-3(mu-CO)(3)(PPh3)(4)] with H2O2. The carbonyl ligands in [Pt-3(mu-CO)(3)(PR3)(3)] (PR3 = PPh3, PPh(2)Bz, PCy3, P'Pr-3) may be completely replaced by sulfur dioxide to give [Pt-3(mu ...
[Pt-3(mu-CO)(3)(PPh3)(3)] was prepared in high yield by the reaction of [Pt-3(mu-CO)(3)(PPh3)(4)] with H2O2. The carbonyl ligands in [Pt-3(mu-CO)(3)(PR3)(3)] (PR3 = PPh3, PPh(2)Bz, PCy3, P'Pr-3) may be completely replaced by sulfur dioxide to give [Pt-3(mu ...
As other monosaccharide mimics such as the azasugars and the carbasugars (with nitrogen and carbon atom, respectively, instead of oxygen atom in the ring) the thiosugars (with sulfur atom instead of oxygen atom in the ring) have gained importance in glycob ...
At low temperature 1-alkoxy-1,3-dienes add to sulfur dioxide activated by a Lewis or Bronstedt acid and generate zwitterionic intermediates that can be quenched by enoxysilanes. The resulting beta,gamma -unsaturated silyl sulfinates can be desilylated and ...
The reactions of (E,E)-1-benzyloxy-2-methylpenta-1,3-diene (9) with 3,3-dimethyl-2-(trimethylsilyloxy)butene and (Z)-3-(trimethylsilyloxy)pent-2-ene in SO2 and a Lewis acid give silyl sulfinates that are quenched with Met to generate the corresponding (Z)- ...