Co(III)‐catalyzed [4+1] annulation of amides with allenes to synthesize isoindolone and 1,5‐dihydro‐pyrrol‐2‐one derivatives is reported. A wide range of aromatic and vinylic amides react with allenes to give the corresponding annulation products in good to excellent yields. The mechanistic studies strongly support that the catalytic reaction proceeds through an amide‐directed C−Hactivation, followed
Chromium‐Catalyzed Selective Dimerization/Hydroboration of Allenes to Access Boryl‐Functionalized Skipped (
<i>E</i>
,
<i>Z</i>
)‐Dienes
作者:Yinsong Zhao、Shaozhong Ge
DOI:10.1002/anie.202012344
日期:2021.1.25
dimerization/hydroboration of allenes is developed to access synthetically versatile boryl‐functionalized skippeddienes with a catalyst generated in situ from CrCl2 and a pyridine‐2,6‐diimine ligand mesPDI. A variety of allenes reacted with pinacolborane (HBpin) to afford the corresponding boryl‐functionalized (E,Z)‐1,4‐dienes in high yields and with excellent selectivity. Electron paramagnetic resonance (EPR) spectroscopic
new cobalt-catalyzed phenolic OH-assisted C–H functionalization of 2-vinylphenols with allenes to give various 2H-chromenes is described. It is the first time that allenes are used as the coupling partners in the cobalt-catalyzed C–H activation reactions. In most cases, cobalt-catalyzed oxidative annulation of arenes with alkenes or alkynes via C–H activation gave [4 + 2] or [3 + 2] cyclization products
Rh<sup>III</sup>-Catalyzed [4 + 1] Annulations of 2-Hydroxy- and 2-Aminobenzaldehydes with Allenes: A Simple Method toward 3-Coumaranones and 3-Indolinones
method for the regio- and stereoselective synthesis of substituted 3-coumaranones from salicylaldehydes and allenes using a rhodium(III) catalyst has been developed. This procedure gives access to new 2-vinyl-substituted 3-coumaranone compounds. The method involves a RhIII-catalyzed aldehyde C–H activation and annulationreactions. Moreover, this RhIII-catalyzed [4 + 1] annulationreaction has been applied
A cobalt-catalyzed C–H/N–H annulation of anilides with allenes to synthesize 1,2-dihydroquinolines is described. The reaction proceeds via a C–H activation, allene insertion, followed by β-hydride elimination and an intramolecular 1,4-addition to a butadiene-group-containing intermediate. Allenes act as a three-carbon source in the present C–H activation strategy.