Khadra Abir, Mayer Stanislas, Organ Michael G
Department of Chemistry, York University, 4700 Keele Street, Toronto, Ontario, M3J1P3, Canada.
BioParc, 850 Bld Sébastien Brant, 67400, Illkirch, France.
Chemistry. 2017 Mar 2;23(13):3206-3212. doi: 10.1002/chem.201605490. Epub 2017 Feb 7.
The Pd-PEPPSI-IPent precatalyst (PEPPSI=pyridine-enhanced precatalyst preparation stabilisation initiation) has been demonstrated to be highly effective in the coupling of hetero(aryl)chlorides to free 2-aminopyridine substrates to produce N-(hetero)aryl-2-aminopyridine derivatives. The catalyst has proven to be competent in a number of other difficult cross-coupling reactions owing to the combination of the 3-pentyl-substituted N-aryl groups and the chlorines on the backbone of the N-heterocyclic carbene (NHC) core. This same reactivity here allows couplings to take place under very mild conditions (e.g., NaBHT (BHT=2,6-di-tert-butyl-4-methylphenol) or carbonate base) such that sensitive functional groups including esters, ketones and nitriles are tolerated. Key is that the same bulk that drives the cross-coupling also mitigates poisoning of the Pd centre with the 2-aminopyridine functionality in the starting materials and/or products, which forces the catalyst into inactive, stable resting states.
钯-PEPPSI-IPent预催化剂（PEPPSI=吡啶增强的预催化剂制备稳定化引发）已被证明在将杂（芳基）氯化物与游离2-氨基吡啶底物偶联以生成N-（杂）芳基-2-氨基吡啶衍生物方面非常有效。由于3-戊基取代的N-芳基基团与N-杂环卡宾（NHC）核心主链上的氯的组合，该催化剂已被证明在许多其他困难的交叉偶联反应中表现出色。这里相同的反应活性使得偶联能够在非常温和的条件下进行（例如，NaBHT（BHT=2,6-二叔丁基-4-甲基苯酚）或碳酸盐碱），从而能够耐受包括酯、酮和腈在内的敏感官能团。关键在于，驱动交叉偶联的相同体积也减轻了起始原料和/或产物中2-氨基吡啶官能团对钯中心的中毒，这迫使催化剂进入无活性、稳定的静止状态。
