在有价值的化合物的合成中,利用二氧化碳 (CO 2 ) 作为一种无毒且可持续的 C1 来源,因其惰性而极具吸引力和挑战性。在这里,我们报告了 C(sp 3 )-F 键与 CO 2通过可见光光氧化还原催化的新型选择性羧化。各种单、二和三氟烷基芳烃以及 α,α-二氟羧酸酯和酰胺在温和条件下进行此类反应,生成重要的芳基乙酸和 α-氟羧酸,包括几种药物和类似物。值得注意的是,机械研究和 DFT 计算证明了 CO 2的双重作用在这种转变过程中作为电子载体和亲电子试剂。氟化底物将通过富电子的 CO 2自由基阴离子进行单电子还原,这些阴离子是通过连续的氢化物转移还原和氢原子转移过程从 CO 2原位生成的。我们预计我们的发现将成为使用惰性底物(包括木质素和其他生物质)进行更具挑战性的 CO 2利用率的起点。
Further studies on silatropic carbonyl ene cyclisations: β-crotyl(diphenyl)silyloxy aldehyde substrates; synthesis of 2-deoxy-2-C-phenylhexoses
作者:Jeremy Robertson、Stuart P. Green、Michael J. Hall、Andrew J. Tyrrell、William P. Unsworth
DOI:10.1039/b804752a
日期:——
carbonyl ene cyclisations of beta-(allylsilyloxy)- and beta-(crotylsilyloxy)butyraldehydes are shown to proceed with high stereoselectivity but at a much reduced rate in comparison to the cyclisation of analogous alpha-substrates. In the second section, olefin cross-metathesis is explored as a route to substituted alpha-(allylsilyloxy)aldehydes and the method applied to the synthesis of diastereomeric
controlled manner. Thus allylation of trisubstituted chlorosilanes (R3SiCl) afforded a variety of aryl, aralkyl, and alkenyl substituted allylsilanes. Dichlorosilanes (R2SiCl2) can either afford monoallylated silanes or diallylated silanes depending on the amount of allylsamarium bromide used. Similarly, trichlorosilanes (RSiCl3) can selectively afford mono-, di-, and tri-allylation products. Finally
Getting up to speed: Both LiCl and the YCl3/MeLi catalyst system have an acceleration effect upon the substitution of silanesusingGrignardreagents (see scheme). The method provides access to benzyl‐, allyl‐, and arylsilanes in good yields from the starting silanes.
Selective mono- and di-allylation and allenylation of chlorosilanes using indium
作者:Zhifang Li、Chenjun Yang、Hongfang Zheng、Huayu Qiu、Guoqiao Lai
DOI:10.1016/j.jorganchem.2008.08.028
日期:2008.12
Allyl and allenyl groups have been introduced into silicon systems by the allylation and allenylation of chlorosilanes using allylbromide or propargyl bromide with indium. The allylation of chlorosilanes afforded a variety of aryl, aralkyl, and alkenyl substituted allylsilanes. By applying this method, the reactions of 1-bromo-3-methylbut-2-ene, 3-bromo-2-methylprop-1-ene and 3-bromobut-1-ene with
Rhodium‐Catalyzed Intermolecular Silylation of C
<sub>sp</sub>
−H by Silacyclobutanes
作者:Tao He、Bin Li、Lichuan Liu、Wenpeng Ma、Wei He
DOI:10.1002/chem.202100084
日期:2021.3.26
The signature reactivity of silacyclobutane (SCB) is their cycloaddition reactions with various π bonds. Recently, the first cases were disclosed where SCBs reacted with both Csp2−H and Csp3−H σ bonds in an intramolecular fashion. Herein, it is reported that SCB is also an efficient reagent for Csp−H bond silylation. Thus, rhodium‐catalyzed intermolecular reactions between SCBs and terminal alkynes