Direct Arylation Reactions Catalyzed by Pd(OH)2/C: Evidence for a Soluble Palladium Catalyst
摘要:
Palladium hydroxide on carbon (Pearlman's catalyst) effectively catalyzes direct arylation reactions of aryl iodides and bromides, providing excellent arylation-to-hydrodehalogenation ratios (> 30:1) with broad scope for both intra- and intermolecular arylation processes. Studies aimed at determining the nature of the active catalyst indicate that an active homogeneous palladium species is produced under the reaction conditions.
arylation of allylic and benzylic alcohols with diaryliodoniumsalts is reported. The reaction yields alkyl aryl ethers under mild and metal-free conditions. Phenols are arylated to diaryl ethers in good to excellent yields. The reaction employs diaryliodoniumsalts and sodium hydroxide in water at low temperature, and excess amounts of the coupling partners are avoided.
Benzylation of phenol was successfully achieved in water under room temperature mediated by tetrabutylammonium bromide (TBAB) for only 2 h affording the corresponding benzyl phenyl ether with good to excellent yields. This protocol is very efficient, simple, avoiding catalysts, easy to work-up after reaction, and especially ‘green’.
Samarium(II)-mediated spirocyclization by intramolecularaddition of arylradicals onto an aromatic ring was achieved by the reaction of N-(2-iodophenyl)-N-alkylbenzamides with SmI2 in the presence of HMPA, yielding spirocyclic indolin-2-one derivatives. The ether congeners afford spirocyclic benzofuran derivatives in moderate yields by arylradicaladdition onto a benzene ring without having an electron-withdrawing
Pd-Catalyzed Homologation of Arylboronic Acids as a Platform for the Diversity-Oriented Synthesis of Benzylic C–X Bonds
作者:Allan J. B. Watson、Kane A. C. Bastick
DOI:10.1055/a-2117-9878
日期:2023.11
platform for the formation of benzylic C–X bonds. Benzylboronic acid pinacol (Bpin) esters are useful synthetic intermediates but are commercially uncommon, leading to preparations that typically rely upon stoichiometric metalation. Pd-catalyzed formal homologation of arylboronic acids provides access to these compounds that, in turn, allow the formation of C–C, C–O, and C–N bonds from Pd- and Cu-mediated
Heat-curing epoxy resin composition containing non-aromatic ureas as accelerator
申请人:SIKA TECHNOLOGY AG
公开号:US11198754B2
公开(公告)日:2021-12-14
Heat-curing epoxy resin compositions are characterized by high impact strength, good storage stability, and a low curing temperature. The epoxy resin compositions are suitable for use as a construction shell adhesive and for producing structural foams. They can already be cured in so-called bottom-baking conditions. Furthermore, it has been found that the use of an accelerator of the formula (Ia) or (Ib) results in an increase of the impact strength of heat-curing epoxy resin compositions.