Copper-Catalyzed Successive C−C bond formations on Indoles or Pyrrole: A Convergent Synthesis of Symmetric and Unsymmetric Hydroxyl Substituted <i>N</i>
-H Carbazoles
C−Cbond formations on indoles and pyrrole approach for the direct synthesis of hydroxyl substitutedN‐H carbazoles is described. The current process represents an atom‐economical method for the preparation of both symmetric and unsymmetric densely substituted and hydroxyl containingN‐H carbazoles from easily accessible starting materials without the need for expensive metals and harsh reaction conditions
excitation due to effective triplet energy transfer from the biacetyl termini to the diarylethene core. Our design makes it possible to switchdiarylethenes with visiblelight in bothdirections in a highly efficient and robust fashion based on extending π‐conjugation and by‐product‐free ring‐closure via the triplet manifold.
developed by inverse-electron-demand oxa-Diels–Alder reaction of α-keto-β,γ-unsaturated esters with α,β-unsaturated hydrazones as electron-rich olefins. This reaction is catalyzed by Eu(hfc)3 and proceeds in an endo-selective manner. This umpolung cycloaddition affords a variety of substituted dihydropyrans stereoselectively in high yields. In addition, indirect synthesis of formyl-substituted dihydropyran
Cobalt(II) chloride catalysed coupling of acetic anhydride with aldehydes. A novel synthesis of asymmetrical 1,2-diones
作者:Saeed Ahmad、Javed Iqbal
DOI:10.1039/c39870000692
日期:——
Cobalt(II) chloride in acetonitrile efficiently catalyses the coupling of aceticanhydride with various aldehydes to the corresponding 1,2-diones in very high yields.
乙腈中的氯化钴(II)以很高的收率有效地催化乙酸酐与各种醛与相应的1,2-二酮的偶合。
Mechanistic Studies on <i>N</i>-Heterocyclic Carbene-Catalyzed Umpolung of β,γ-Unsaturated α-Diketones
proposed mechanism, the calculations revealed a more complicated process involving both nucleophilic O-acylated homoenolate and electrophilic α,β-unsaturated acyl azolium intermediates. The experimental studies confirmed the existence of the aforementioned two key intermediates. A revised mechanism has been proposed to demonstrate the detailed mechanistic insights into the product formation.