An efficient protocol for the synthesis of indenones has been developed from the annulation of benzoic esters and internal alkynes by exploiting cobalt catalyst.
in good yield. Control experiments revealed that the reactions proceed through a multi-step reaction sequence involving a novel intramolecular transamination to the α-acetylenic carbon of the alkynyl group. The method was applicable to the synthesis of dibenzopentalene derivatives as well as various indenone derivatives. A mechanism for the reaction is discussed.
9-benzoylcarbazoles with internal alkynes proceeds efficiently through ortho C–H and C–N bond cleavages. This reaction provides direct access to variously substituted indanone derivatives. The carbazolyl leavinggroup can be readily recovered and reused for preparing the starting materials. Keywords: annulation; rhodium catalyst; C–H bond cleavage
Rhodium(III)‐Catalyzed Redox‐Neutral Synthesis of Indenones from 2‐Aryl‐3‐nitrosoindoles with Alkynes
作者:Cheng Li、Bin Zhao、Guojiang Mao、Guo‐Jun Deng
DOI:10.1002/adsc.202300639
日期:2023.10.24
Herein, we developed a rhodium(III)-catalyzedsynthesis of indenones from 2-aryl-3-nitrosoindoles and alkynes in a redox-neutral manner. The reaction did not require harsh conditions or any external oxidants. Mechanistic experiments and DFT calculation revealed that the reaction involved directed C−H activation, dearomative spirocyclization, N−O/C−C bond cleavage and ketimine hydrolysis cascade processes