Pd-Catalyzed Oxidative Annulation of Aryl Ethers with Alkynes: Synthesis of Functionalized Spirocycles and Naphthalenes
作者:Shiyong Peng、Zhonghao Sun、Huijuan Zhu、Nuan Chen、Xiaobo Sun、Xiaojie Gong、Jian Wang、Lei Wang
DOI:10.1021/acs.orglett.0c00970
日期:2020.4.17
dearomative [2+2+1] annulations of aryl ethers with alkynes are reported via para-selective C-H functionalization, providing highly functionalized spirocyclohexadienones in moderate to excellent yields undermild reaction conditions. Importantly, mechanistic investigation indicated an unusual C-O bond cleavage was involved. Moreover, polyarylated naphthalenes could be obtained via oxidative [2+2+2] annulation
Alkynes and phenoldiazoniumsalts undergo a Pd‐catalyzed [2+2+1] cyclization reaction to spiro[4,5]decatetraene‐7‐ones. This structure was confirmed for one example by X‐ray single‐crystal structure analysis. The reaction is believed to proceed through oxidative addition of the phenoldiazonium cation to Pd0, subsequent insertion of two alkynes, followed by irreversible spirocyclization.