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第12讲-亲核参与烯烃的亲电加成反应：卤素、卡宾和硼烷Lecture 12 - Nucleophilic Participation During Electrophilic Addition to Alkenes: Halogen, Carbene, and Borane |
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| 课程网址: | http://videolectures.net/yalespan125bs2011_mcbride_lec12/ |
| 主讲教师: | J. Michael McBride |
| 开课单位: | 耶鲁大学 |
| 开课时间: | 2014-08-19 |
| 课程语种: | 英语 |
| 中文简介: |  |
| 课程简介: | When electrophilic addition involves a localized carbocation intermediate, skeletal rearrangement sometimes occurs, but it can be avoided when both alkene carbons are involved in an unsymmetrical 3-center-2-electron bond, as in Markovnikov hydration via alkoxymercuration followed by reduction. Similarly a reagent that attacks both alkene carbons simultaneously by providing a nucleophilic component during electrophilic attack can avoid rearrangement, as in reactions that proceed via three-membered-ring halonium intermediates. Simultaneity in making two bonds during formation of cyclopropanes from carbenes can be demonstrated using stereochemistry. Anti-Markovnikov hydration can be achieved via hydroboration followed by oxidation with hydroperoxide. Rearrangement of the borane hydroperoxide intermediate with frontside C-O bond formation shows close orbital analogy to backside attack during SN2 substitution. Again syn-addition shows that nucleophilic attack occurs simultaneously with electrophilic attack on the alkene. |
| 关 键 词: | 亲电加成; 烯烃; 亲核攻击 |
| 课程来源: | 视频讲座网 |
| 数据采集: | 2021-11-18：zkj |
| 最后编审: | 2021-12-20：liyy |
| 阅读次数: | 69 |