TiCl4-Mg-CHBr3 Promoted Bromo and Dibromomethylenation of Ketones and Aldehydes; Concise Asymmetric Synthesis of the Epoxycyclohexenone Model Core of Scyphostatin and Isariotin E

• Main Authors: Yeshwant Ramchandra Bhorge, 葉栩
• Other Authors: Tu-Hsin Yan
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/60450891763633396181

博士 === 國立中興大學 === 化學系所 === 100 === In the first chapter, we described CBr2 transfer reaction of CHBr3 promoted Mg-TiCl4 represents an extremely simple, practical, and selective dibromomethylenation of a variety of ketones and aldehydes, especially in enolizable or sterically hindered ketones such as 2,2-dimethylcyclohexanone. In chapter second, we extended TiCl4-Mg promoted coupling of CHBr3 with various aldehydes and ketones, especially in sterically hindered or enolizable ketones, provides a simple, practical, and stereoselective carbonyl-bromomethylenation leading primarily to (E)-vinyl bromides. In third chapter, we achieved concise asymmetric synthesis of the epoxycyclohexenone model core of Scyphostatin and Isariotin E was synthesized in an enantioselective manner starting from the commercially available and cheap C2-symmetric L-tartaric acid served as the chiral building block. A new strategy invoking a new application of a coupling reaction of carbonyl substrate with Grignard reagent to construct the asymmetric quaternary carbon center and a stereospecific epoxie ring formation as the key steps.