Tertiary and Quaternary Carbon Formation via Gallium-Catalyzed Nucleophilic Addition of Organoboronates to Cyclopropanes
Tertiary and Quaternary Carbon Formation via Gallium-Catalyzed Nucleophilic Addition of Organoboronates to Cyclopropanes
复制标题
通过镓催化有机硼酸酯与环丙烷的亲核加成形成叔碳和季碳
DOI：
10.1021/acs.orglett.7b03349
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发表时间：
2017
期刊：
影响因子：
5.2
通讯作者：
May, Jeremy A.
中科院分区：
文献类型：
--
作者：
Nguyen, Truong N.;May, Jeremy A.
GaCl 3和（IPr）GaCl 3/AgSbF 6通过有机硼亲核试剂与二酯和酮官能化的环丙烷的同共轭加成反应生成γ-叔碳和γ-季碳。不需要电子供体基团环丙烷取代基，允许使用缺电子的芳基、烯基、烷基和氢取代的环丙烷。催化条件与烯基、炔基和芳基亲核试剂，包括邻位取代的芳族化合物相容，以合成高度受阻的季碳。炔基亲核试剂形成取代的环戊烯。对照实验支持季碳中心形成中的中间碳阳离子。
GaCl3and (IPr)GaCl3/AgSbF6formed γ-tertiary and γ-quaternary carbons via homoconjugate addition of organoboron nucleophiles to diester- and ketone-functionalized cyclopropanes. Electron donor group cyclopropane substituents were not needed, allowing electron-deficient aryl, alkenyl, alkyl, and hydrogen-substituted cyclopropanes to be used. The catalytic conditions were compatible with alkenyl, alkynyl, and aryl nucleophiles, including ortho-substituted aromatics, to synthesize highly hindered quaternary carbons. Alkynyl nucleophiles formed substituted cyclopentenes. A control experiment supports an intermediate carbocation in quaternary carbon center formation.