New Synthetic Methods : Polyene Cyclization and Pd(II)-Mediated Cyclization Reation

• Main Authors: Huang-Min Wu, 吳皇旻
• Other Authors: Hsing-Jang Liu
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/95959522718122239303

碩士 === 國立清華大學 === 化學系 === 91 === The first chapter of this thesis details efforts towards the application of the polyene cyclization process for the construction of bridged bicyclic systems. The starting α´-substituted enone esters 24 and 25 were synthesized via Stork-Danheiser alkylation of 2-carbomethoxy-4,4-dimethyl-2-cyclohexenone with allyl bromide and 3-butenyl bromide respectively. The Lewis acid promoted polyene cyclization reaction of 24 and 25 to give the corresponding bicyclic [2.2.2]- and [2.3.2]-systems were subsequently individually explored. Surprisingly, in addition to the expected bicyclic product 26, bicyclic compounds 29 and 30 respectively were also isolated. The second chapter describes the investigation of a novel intramolecular palladium(II) promoted cyclization of activated methines onto terminal olefins. Keto esters 71, 80, 89, and 98 were synthesized from readily available starting materials and individually treated with palladium(II) acetate. In all cases except one, products (105, 110 and 112) resulting from attack of the α-carbon onto the terminal olefin in an exo-fashion were produced, giving rise to bicyclic compounds bearing an exocyclic double bond. Interestingly, upon exposure to palladium(II) acetate, keto ester 80 gave rise to dihydrofuran 102.