Palladium-catalyzed C-C coupling under thermomorphic conditions
Palladium-catalyzed C-C coupling under thermomorphic conditions
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DOI：
10.1021/ja001708g
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发表时间：
2000-09-27
影响因子：
15
通讯作者：
Sink, EM
中科院分区：
文献类型：
--
作者：
Bergbreiter, DE;Osburn, PL;Sink, EM
描述了在升高的温度下表现出相分散性增加的液-液两相体系以及在环境温度下具有强相优先性的可溶性聚合物结合的催化剂。在这样的系统中，通过液/液分离进行产物分离和催化剂回收。该报告描述了这种热形态催化剂回收系统在钯催化的碳-碳键形成反应中的应用。聚（N-异丙基丙烯酰胺）（PNIPAM）结合的膦配体与先前在烯丙基取代化学中使用的Pd（0）催化剂在Heck、Suzuki和sp-sp（2）交叉偶联反应中是有效的催化剂。还描述了与PNIPAM或聚（乙二醇）（PEG）结合的空气稳定的三齿SCS-Pd（II）催化剂。这些SCS催化剂的一个特别的优点是，对于聚合物结合的SCS-PdCl催化剂，不需要采取针对偶然催化剂氧化的预防措施;因此避免了耗时的溶剂纯化和脱气方案。
Liquid-liquid biphasic systems that exhibit an increase in phase miscibility at elevated temperature together with soluble polymer-bound catalysts that have a strong phase preference at ambient temperature are described. In such systems, product isolation and catalyst recovery are effected by a liquid/liquid separation. This report-describes the use of such thermomorphic catalyst recovery systems for palladium-catalyzed carbon-carbon bond forming reactions. Poly(N-isopropylacrylamide) (PNIPAM)-bound phosphine ligands with a Pd(0) catalyst used previously in allylic substitution chemistry are efficient catalysts in Heck, Suzuki, and sp-sp(2) cross-coupling reactions. Air-stable tridentate SCS-Pd(II) catalysts bound to PNIPAM or poly(ethylene glycol) (PEG) are also described. A particular advantage of these SCS catalysts is that no precautions against adventitious catalyst oxidation need be taken with the polymer-bound SCS-PdCl catalysts; thus avoiding time-consuming solvent purification and degassing protocols.