- 作者: 方俊民 ; 陳明毅
- 作者服務機構: 台灣大學化學系
- 中文摘要: The dienyl anion, generated from metallation of 2-(1,3-pentadienyl)-1,3-dithiane with n-BuLi in THF, reacted exclusively at the C-1 position (.alpha.-site) with alkylating agents and ketones, but it showed some tendency toward the C-3 position (. gamma.-site) in the reactions with benzyl bromide and aliphatic aldehydes. No reaction at the C-5 position (.epsilon.-site) was observed in any studied case. Examination of the related propanedithio-substituted allylic anions having various .gamma.- substituents revealed that the regiochemistry was remarkably influenced by the.gamma.-substituents and the attacking electrophiles. The electronic effect according to the principle of hard and soft acids and bases is proposed to account for the observed regiochemistry, while the steric factor was minor. Two trienes, obtained by alkylations of the dienyl anion with 4-bromo-1-butene and 5-pentenyl methanesulfonate, were applicable to intramolecular Diels-Alder reactions to give bicyclic compounds.
- 英文摘要: --
- 中文關鍵字: Dithiane; Allylic Anion; Regiochemistry; Hard And Soft Acid And Base Principle (Hsab); Electrophilic Reaction; Propanedithio-Substituted Reaction
- 英文關鍵字: 二硫陸圜;烯丙基陽離子;位向化學;硬軟酸鹼原則;親電子性反應;二硫丙烷基取代反應