- 作者: 葉儒隆 ; 蔣維棠 ; 蔡蘊明
- 作者服務機構: 台灣大學化學系
- 中文摘要: Starting from malonate, a practical route was developed for the synthesis of .alpha.-phenylthio acid 3. Several chiral compounds including (-)-menthol, (-)-8- phenylmenthol and a camphor based oxazolidinone 8 reacted with 3 to give .alpha.-phenylthio esters or amide. These sulfides cyclized efficiently when reacted with tributyltin hydride. Among the chiral auxiliaries used, 8-phenylmenthyl group displayed moderate asymmetric induction (64% ee for cis-product and 40% ee for trans-product). Based on this results, a transition state model was proposed to explain the observed stereoselectivity. In this model, due to.pi.,.pi.-orbital overlap of the phenyl ring and the carbonyl, the si-face of the most stable conformer of the radical was shielded. This controlled the carbon-carbon bond formation to occur from the re-face.
- 英文摘要: --
- 中文關鍵字: Asymmetric Radical; Radical Cyclization; Phenylmethol; Chiral Auxiliary; Tributyltin Hydride; Ester Radical; Amide Radical
- 英文關鍵字: 非對稱自由基;自由基環化反應;苯甲醇;光學輔助體;氫三丁基錫;酯自由基;醯胺自由基