Efficient Synthesis of Orphaned Cyclopropanes Using Sulfones as Carbene Equivalents
作者:John Douglas Johnson、Charles Reece Teeples、Nicholas Rajai Akkawi、Sidney M. Wilkerson-Hill
DOI:10.1021/jacs.2c07063
日期:2022.8.17
but are difficult to synthesize using state-of-the-art metal-catalyzed carbene transfer methods without competing 1,2-hydride shifts. Herein, we introduce a mechanistically distinct platform to transfer 1,1-dialkylcarbene units to olefins using carbometalation reactions of dialkyl sulfonyl anions. In the presence of NaNH2 or n-BuLi in ethereal solvents, dialkyl sulfones react with styrenes and arylbutadienes
One-pot oxo-amination of unactivated cyclopropanes with safe, green dioxygen as an oxidant and low-cost amines as nitrogen sources has generated interest since this can directly result in uniform β-located difunctional units. Formation of the three-electron cation radical followed by the nucleophilic attack of amines to open the strained ring of cyclopropanes catalyzed by classic noble-complex photocatalysts
使用安全、绿色的双氧作为氧化剂和低成本的胺作为氮源,对未活化的环丙烷进行一锅法氧代胺化引起了人们的兴趣,因为这可以直接产生均匀的 β 位双功能单元。形成三电子阳离子自由基,然后胺的亲核攻击打开由经典贵金属络合物光催化剂催化的环丙烷的应变环是一种有前途的策略。然而,这种开环途径无法维持整个二级亲核取代(S N2) 转化率,这通常导致对映体选择性不令人满意(对映体过量(ee)值~60%)。在这里,我们证明了对于环丙烷与良性分子氧和吡唑的这种一步氧代胺化,可以首先通过 TiO 2光催化剂实现高度均匀的构型反转。该策略具有低成本、半多相光催化和环境友好的反应条件,无需使用任何牺牲试剂或添加剂。重要的是,我们的方案不仅提供了相对广泛的底物范围,可耐受一定范围的取代环丙烷和吡唑,从而产生具有出色转化率和收率的各种 β-氨基酮产品(~50 个示例),而且还保留了出色的对映选择性(ee 值~99%)。一致
Photochemical series. 141. Reactivity of aryl vinyl di-.pi.-methane systems. Mechanistic and exploratory organic photochemistry
作者:Howard E. Zimmerman、Richard L. Swafford
DOI:10.1021/jo00191a007
日期:1984.8
Arylcyclopropane photochemistry. Substituent effects on the photochemical 1,3-hydrogen migration of 1,1-dimethyl-2-phenylcyclopropane
作者:Stephen S. Hixson、Charles R. Gallucci
DOI:10.1021/jo00247a009
日期:1988.6
Catalytic Olefin Cyclopropanation with In Situ-Generated Dialkyl Diazomethanes via Co(II)-Based Metalloradical Catalysis
作者:Bao-Gui Cai、Claire Empel、Sripati Jana、Jun Xuan、Rene M. Koenigs