Synthesis of 2-Alkylidenethietanes and the transformation to Thiophenes

• Main Author: Xiao, Yongjun
• Other Authors: Narasaka, Koichi
• Format: Theses and Dissertations
• Language: English
• Published: 2009
• Subjects: DRNTU::Science::Chemistry::Organic chemistry
• Online Access: http://hdl.handle.net/10356/14732
• Institution: Nanyang Technological University

During the course of study on the nucleophilic substitution reaction at an sp2 carbon in the Narasaka group, a unique four-membered ring formation was realized by intramolecular nucleophilic vinylic substitution of a thiolate moiety. To generalize this 2-alkylidenethietane formation and to get more mechanistic information, synthesis of 2-alkylidenethietanes were examined by using this newly developed synthetic methodology. It was found that 2-alkylidenethietanes were oxidized to 2-alkylidenethietan- 1-oxides by treatment with m-CPBA, which has a unique structure with a strained four-membered ring, an exo double bond, and a sulfinyl group. Accordingly, the transformation of 2-alkylidenethietan-1-oxides were investigated. Incidentally, it was discovered that the treatment of 2-alkylidenethietan-1-oxides with p-toluenesulfonic acid afforded the unexpected thiophenes. The thiophene formation was extensively studied in this MSc’s thesis.