Practical Large Scale Preparation of Activated Cyclopropanes
作者:Tania Lavoisier、Jean Rodriguez
DOI:10.1080/00397919608003644
日期:1996.2
Abstract Simple and practical experimental conditions for the large scale preparation of activatedcyclopropanes by K2CO3 promoted cycloalkylation of malonate precursors with 1,2-dibromoethane are described.
1,1,3,3-Tetramethyldisiloxane (TMDS) and polymethylhydrosiloxane (PMHS), when associated with titanium(IV) isopropoxide, provide two convenient systems for the reduction of nitriles into the corresponding primary amines. Kinetics of the two systems have been studied by 1H NMR and demonstrated that reduction with PMHS occurs faster than with TMDS. These two titanium-based systems reduce both aromatic
1,1,3,3-四甲基二硅氧烷(TMDS)和聚甲基氢硅氧烷(PMHS)与异丙醇钛(IV)结合使用时,提供了两个方便的系统,可将腈还原为相应的伯胺。通过1 H NMR研究了这两个系统的动力学,结果表明,用PMHS进行还原的速度比用TMDS进行还原的速度更快。在存在Br,CC,NO 2的情况下,这两个钛基体系同时还原芳族和脂肪族腈,OH和环丙基环。在环丙基腈的情况下,观察到由于分子间还原性烷基化反应而形成的仲胺。该结果被用于还原二腈,其通过分子内还原性烷基化反应一步一步导致了氮杂环庚烷,哌啶,吡咯烷和氮杂环丁烷衍生物。
Formation of Cyclopropanes and Epoxides from Vinylselenonium Salts
作者:Yoshihiko Watanabe、Yoshio Ueno、Takeshi Toru
DOI:10.1246/bcsj.66.2042
日期:1993.7
Treatment of vinyl- and (5-oxo-1-cyclopentenyl)selenonium tetrafluoroborates 2 and 4 with a variety of carbanions gives cyclopropane derivatives 3 and 5 in good yields. The reaction of vinylselenonium salt 2 with sodium alkoxides in the presence of aldehydes gives various kinds of glycidyl ethers 7 in excellent yields. The reaction of 2 with hydroxyacetone in the presence of K2CO3 affords cyclized
Boron tribromide as a reagent for anti-Markovnikov addition of HBr to cyclopropanes
作者:Matthew H. Gieuw、Shuming Chen、Zhihai Ke、K. N. Houk、Ying-Yeung Yeung
DOI:10.1039/d0sc02567d
日期:——
Although radical formation from a trialkylborane is well documented, the analogous reaction mode is unknown for trihaloboranes. We have discovered the generation of bromine radicals from boron tribromide and simple proton sources, such as water or tert-butanol, under open-flask conditions. Cyclopropanes bearing a variety of substituents were hydro- and deuterio-brominated to furnish anti-Markovnikov
“On water” palladium catalyzed diastereoselective boronic acid addition to structurally diverse cyclopropane nitriles
作者:Dwaipayan Das、Prasun Mukherjee、Asish R. Das
DOI:10.1039/d0ob00077a
日期:——
An efficient palladium catalyzeddiastereoselective addition of arylboronic acids to complex spirocyclopropyl dinitriles is developed in the presence of a catalytic amount of 4-dodecylbenzenesulphonic acid (DBSA) as a Brønstedacid surfactant in aqueousmedia. The protocol is also found to be highly effective when different types of nitrile compounds and organo-boron compounds are used. The overall