Alkoxy- and amidocarbonylation of functionalised aryl and heteroaryl halides catalysed by a Bedford palladacycle and dppf: a comparison with the primary Pd(ii) precursors (PhCN)2PdCl2 and Pd(OAc)2
作者:Ian J. S. Fairlamb、Stephanie Grant、Peter McCormack、John Whittall
DOI:10.1039/b615874a
日期:——
The versatility of a Bedford-type palladacycle 1, namely [Pd(µ-Cl)κ2-P,C-P(OC6H2-2,4-tBu2)(OC6H3-2,4-tBu2)2}}2], as a primary Pd source, in combination with the ligand bis-1,1′-(diphenylphosphino)ferrocene (dppf) has been established in carbonylation reactions of aryl and heteroaryl bromides with methanol, piperidine and related nucleophiles. Palladacycle 1 has been compared with other primary Pd sources, e.g. (PhCN)2PdCl2 and Pd(OAc)2. The efficacy of the carbonylation processes appear to be linked to the [Pd] concentration, substrate : catalyst ratio, CO pressure and reaction temperature. In amidocarbonylation, double carbonylation is observed for certain organohalides. In the case of 2,5-dibromopyridine, regioselective amination (Hartwig–Buchwald type) also occurs as a side-reaction.
一种Bedford型钯环化合物1,即[Pd(µ-Cl)κ2-P,C-P(OC6H2-2,4-tBu2)(OC6H3-2,4-tBu2)2}}2],作为主要的钯源,其多功能性已在与醇、哌啶及相关亲核试剂的芳基和杂芳基溴化物的羰基化反应中得到证实。钯环化合物1已与其他主要的钯源进行比较,例如(PhCN)2PdCl2和Pd(OAc)2。羰基化过程的有效性似乎与[钯]浓度、底物与催化剂的比例、一氧化碳压力和反应温度有关。在胺羰基化过程中,某些有机卤化物观察到了双羰基化现象。在2,5-二溴吡啶的情况下,还发生了区域选择性氨基化(Hartwig–Buchwald型)的副反应。