A novel approach of cycloaddition of difluorocarbene to α,β-unsaturated aldehydes and ketones: synthesis of gem-difluorocyclopropyl ketones and 2-fluorofurans
作者:Wei Xu、Qing-Yun Chen
DOI:10.1039/b212232d
日期:2003.3.27
acetals and ketals are easily obtained in moderate yields from the [1 + 2] cycloaddition of difluorocarbene to 1,3-dioxolanes of alpha,beta-unsaturated aromatic aldehydes and ketones. Hydrolysis of these fluorinated compounds under acidic conditions either gives the corresponding gem-difluorocyclopropyl ketones or 1-aryl-2-fluorofuran derivatives through intramolecular carbonium rearrangement with simultaneous
a carbon-centered radicalintermediate, which will overcome side reactions during the styrene radical functionalization process. Experimental studies have provided evidence indicating a domino-fluorination–protodefluorination pathway with α-keto acid initiating the photoredox cycle. The present catalytic protocol also affords a novel approach for the construction of α,β-unsaturated ketones under mild
Polyaniline coated on celite, a heterogeneous support for palladium: applications in catalytic Suzuki and one-pot Suzuki–aldol reactions
作者:Heta A. Patel、Arun L. Patel、Ashutosh V. Bedekar
DOI:10.1039/c6nj02402e
日期:——
Particles of celite were coated with polyaniline, characterized and used as a support for heterogenization of palladium metal ions. The prepared heterogeneous palladium catalysts were screened for Suzuki–Miyaura and one-pot Suzuki–aldol reactions with high conversions. The process of heterogenization on celite reduces the PANI consumption ten-fold when anchoring palladium ions onto the support. The
nitrogen-based heteroaromatic systems. Here we report the first case of an organic oxygenated aromatic system, in particular the tri-aryl-pyrylium tetrafluoroborate system, for which noncovalent anion–π interactions of the pyryliumcation with the tetrafluoroborate anion have been experimentally detected and demonstrated by means of 19F NMRspectroscopy in solution. A series of pyrylium tetrafluoroborate