Pd-PEPPSI-IPent: Low-Temperature Negishi Cross-Coupling for the Preparation of Highly Functionalized, Tetra-ortho-Substituted Biaryls
作者:Selçuk Çalimsiz、Mahmoud Sayah、Debasis Mallik、Michael G. Organ
DOI:10.1002/anie.200906811
日期:2010.3.8
Cool couplings: Complex, hindered biaryls have been prepared at temperatures ranging from 0°C to room temperature, or with gentle heating. The Pd‐PEPPSI‐IPent catalyst (see scheme) nicely couples starting materials containing acidic moieties and routinely prepares biaryl derivatives where one or both rings comprising the biaryl are heterocyclic. Ar1=hindered aryl or heteroaryl, Ar2=unactivated aryl
Pd-PEPPSI-IPent: An Active, Sterically Demanding Cross-Coupling Catalyst and Its Application in the Synthesis of Tetra-Ortho-Substituted Biaryls
作者:Michael G. Organ、Selçuk Çalimsiz、Mahmoud Sayah、Ka Hou Hoi、Alan J. Lough
DOI:10.1002/anie.200805661
日期:2009.3.16
series of N‐heterocyclic carbene catalysts (see picture) were prepared and evaluated in the Suzuki–Miyaura reaction. A variety of sterically encumbered tetra‐ortho‐substituted biaryl products were formed from unreactive aryl chlorides using the isopentyl‐substituted catalyst at temperatures ranging from 65 °C to room temperature. The cyclopentyl‐substituted catalyst was virtually inactive, demonstrating