| Budget Amount *help |
¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2016: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
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| Outline of Final Research Achievements |
Despite the wide synthetic utility of onium salts as reagents and catalysts, the catalytic ability of tertiary sulfonium salts has not yet been demonstrated well in organic synthesis. To create new possibilities for sulfonium salts as catalysts, we focused on the hydrogen-bonding abilities of α hydrogens on alkylsulfonium salts when we reported the use of new tetraalkylammonium salts as hydrogen-bonding catalysts. Based on the design of the ammonium salts, we focused on simple cyclic trialkylsulfonium salts. The catalytic ability of sulfonium salts was superior to that of the related ammonium salts. We have also demonstrated that chiral tertiary sulfonium salts can promote asymmetric reactions. Binaphthyl-modified bifunctional sulfonium salts were efficient catalysts for the asymmetric reactions under base-free phase-transfer conditions. As far as could be ascertained, this is the first example of a highly enantioselective reaction catalyzed by chiral sulfonium salts.
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