Cooperative Catalytic Activation of Si−H Bonds by a Polar Ru−S Bond: Regioselective Low-Temperature C−H Silylation of Indoles under Neutral Conditions by a Friedel−Crafts Mechanism
作者:Hendrik F. T. Klare、Martin Oestreich、Jun-ichi Ito、Hisao Nishiyama、Yasuhiro Ohki、Kazuyuki Tatsumi
DOI:10.1021/ja111483r
日期:2011.3.16
Merging cooperative Si-H bond activation and electrophilic aromatic substitution paves the way for C-3-selective indole C-H functionalization under electronic and not conventional steric control. The Si-H bond is heterolytically split by the Ru-S bond of a coordinatively unsaturated cationic ruthenium(II) complex, forming a sulfur-stabilized silicon electrophile. The Wheland intermediate of the subsequent
合并协同的 Si-H 键活化和亲电芳香取代为在电子而非传统空间控制下的 C-3 选择性吲哚 CH 官能化铺平了道路。Si-H 键被配位不饱和阳离子钌 (II) 配合物的 Ru-S 键异裂,形成硫稳定的硅亲电试剂。假设随后的 Friedel-Crafts 型过程的 Wheland 中间体被硫原子去质子化,不需要添加碱。整个催化过程在低温下无需溶剂,仅释放二氢。