Stereocontrolled Synthesis of 1,5-Stereogenic Centers through Three-Carbon Homologation of Boronic Esters
作者:Phillip J. Unsworth、Daniele Leonori、Varinder K. Aggarwal
DOI:10.1002/anie.201405700
日期:2014.9.8
Allylic pinacol boronic esters are stable toward 1,3‐borotropic rearrangement. We developed a PdII‐mediated isomerization process that gives di‐ or trisubstituted allylic boronic esters with high E selectivity. The combination of this method with lithiation–borylation enables the synthesis of carbon chains that bear 1,5‐stereogeniccenters. The utility of this method has been demonstrated in a formal
Deaminative Borylation of Aliphatic Amines Enabled by Visible Light Excitation of an Electron Donor-Acceptor Complex
作者:Frederik Sandfort、Felix Strieth-Kalthoff、Felix J. R. Klauck、Michael J. James、Frank Glorius
DOI:10.1002/chem.201804246
日期:2018.11.22
strategy for the borylation of aliphatic primary amines is described. Alkyl radicals derived from the single‐electron reduction of redox‐active pyridinium salts, which can be isolated or generated in situ, were borylated in a visible light‐mediated reaction with bis(catecholato)diboron. No catalyst or further additives were required. The key electron donor–acceptor complex was characterized in detail
triorganocerium reagents and their application in catalyst‐free Zweifel olefinations. These unique cerium species were generated through novel exchange reactions of organohalides with n‐Bu3Ce reagents. The adequate electronegativity of cerium allowed for compensating the disadvantages of both usually functional‐group‐sensitive organolithium species and less reactive organomagnesium reagents. Exchange reactions
描述了三有机铈试剂的原位形成及其在无催化剂的Zweifel烯烃中的应用。这些独特的铈物种是通过有机卤化物与n- Bu 3 Ce试剂的新型交换反应生成的。铈具有足够的负电性,可以弥补通常对官能团敏感的有机锂物质和反应性较低的有机镁试剂的缺点。在芳基和烯基溴上进行交换反应,从而实现手性硼频哪醇酯的对映体特异性转化。最终,这些新的有机铈物种参与了可选择性和空间受阻的酮的选择性1,2-加成反应。
Selective Coupling of 1,2‐Bis‐Boronic Esters at the more Substituted Site through Visible‐Light Activation of Electron Donor–Acceptor Complexes
作者:Hui Wang、Jingjing Wu、Adam Noble、Varinder K. Aggarwal
DOI:10.1002/anie.202202061
日期:2022.4.25
monofunctionalization of 1,2-bis-boronic esters was achieved by using a catalyst-free photoinduced coupling with (hetero)aryl nitriles. The reaction proceeds throughelectrondonor–acceptor (EDA) complex-driven deboronation and radical 1,2-boron shift, giving β-aryl primary boronicester products. The reaction also works with primary, secondary, and tertiary boronicesters.
Vinyl boron ate complexes of enantioenriched secondary alkyl pinacolboronic esters undergo stereospecific radical-induced 1,2-migration in radical polar crossover reactions. In this three-component process various commercially available alkyl iodides act as radical precursors and light is used for chain initiation. Subsequent oxidation and protodeborylation leads to valuable α-chiral ketones and chiral