In Situ Brønsted Acid Activated Cyclometalated N-Heterocyclic Carbene-Au(III)-Sulfonamide Complexes as Precatalysts for Alkyne Activation in Benzofuran Synthesis
作者:Otto Seppänen、Anna Lenarda、Martin Nieger、Juho Helaja
DOI:10.1021/acs.organomet.3c00520
日期:2024.3.11
Cyclometalated N-heterocyclic carbene (NHC)-NTs-AuCl2 complexes of type [(NHC)Au(N)Cl2] are presented as a stable precatalyst, easily activated in situ by an acid (HX) for cationic [(NHC)AuCl2]X catalysis. The “ethyl-and propyl-tosylamide arm” tethered NHC-Au(III)Cl3 complexes can be smoothly converted to cyclometalated (-HCl) analogues by K2CO3 treatment, and, via the addition of a stoichiometric
[(NHC)Au(N)Cl 2 ]类型的环金属化N-杂环卡宾(NHC)-NTs-AuCl 2配合物是一种稳定的预催化剂,很容易被酸(HX)原位激活,产生阳离子[(NHC) AuCl 2 ]X催化。通过 K 2 CO 3处理以及添加化学计量的布朗斯台德酸,“乙基和丙基甲苯磺酰胺臂”束缚的 NHC-Au(III)Cl 3配合物可以顺利转化为环金属化 (-HCl) 类似物(HX),可进一步转化为携带各种抗衡阴离子的[NHC-Au(III)Cl 2 ]X (X = CCl 3 CO 2 – , CF 3 CO 2 – , MsO – , TsO – , BF 4 – , TfO –、Tf 2 N – )。我们使用 2-炔基苯酚环异构化为苯并呋喃作为探针反应,研究了这一催化概念。在环境条件下,在CHCl 3中,使用等摩尔1mol%负载的Mes-NHC-丙基-NTs-AuCl 2预催化剂和MsOH作为