开发了将烯丙基硅烷转化为官能化烯的三步路线。1,1-二溴-2-(甲硅烷基甲基)环丙烷的热分解,通过用CHBr 3 / KO t处理烯丙基硅烷衍生物定量制备Bu,得到取代的2-溴-1,3-丁二烯,并且消除了溴硅烷。溴代双烯与软亲核试剂的钯催化反应生成了丙二烯衍生物。也可以通过该方法制备以前难以获得的三和四取代的烯。
作者:Manuel Mahlau、Pilar García-García、Benjamin List
DOI:10.1002/chem.201203623
日期:2012.12.14
Lewis acid catalyzed Hosomi–Sakuraireaction of (hetero)aromatic aldehydes and allylsilanes using an easily handled disulfonimide precatalyst (see scheme). The key to the success of this system is to turn the usually undesired silylium ion catalysis into the desired catalytic regime and pair the cation with an enantiopure disulfonimide anion, thereby applying the concept of asymmetric counteranion‐directed
organic synthesis due to their high reactivity. Herein, we report a Lewis acid-catalyzed cross-coupling reaction of mono- and disubstituted gem-difluorinated cyclopropanes with nucleophiles. The formation of a fluoroallyl cation species triggered via the Lewisacid-assisted activation of the C–F bond is proposed in this transformation. The cation species is then trapped by the nucleophiles, including
Trityl Cation-Catalyzed Hosomi-Sakurai Reaction of Allylsilane with β,γ-Unsaturated α-Ketoester to Form γ,γ-Disubstituted α-Ketoesters
作者:Zubao Gan、Deyun Cui、Hongyun Zhang、Ying Feng、Liying Huang、Yingying Gui、Lu Gao、Zhenlei Song
DOI:10.3390/molecules27154730
日期:——
(Ph3C)[BPh(F)4]-catalyzed Hosomi-Sakurai allylation of allylsilanes with β,γ-unsaturated α-ketoesters has been developed to give γ,γ-disubstituted α-ketoesters in high yields with excellent chemoselectivity. Preliminary mechanistic studies suggest that trityl cation dominates the catalysis, while the silyl cation plays a minor role.