Ru-catalysed C(sp2)-H vinylation/annulation of benzoic acids and alkynes: rapid access to medium-sized lactones
Xiao-Qiang Hu1, Zi-Kui Liu, Ye-Xing Hou
1Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science, School of Chemistry and Materials Science, South-Central University for Nationalities, Wuhan 430074, China. huxiaoqiang@mail.scuec.edu.cn.
Abstract:
An unprecedented ruthenium catalysed [4+4] annulation of readily available benzoic acids and alkynes is reported for the first time. The carboxylate group acts as both a directing group and an internal nucleophilic reagent to facilitate a C(sp2)-H vinylation/annulation cascade. This reaction avoids the classically oxidative [4+2] annulation, allowing the efficient synthesis of a wide array of eight-membered lactones under oxidant-free conditions. Moreover, this catalytic system can be successfully extended to [4+3] and [4+5] annulations for the assembly of seven- and nine-membered lactones.
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