Synthesis of 2<i>H</i>-Chromenes via Hydrazine-Catalyzed Ring-Closing Carbonyl-Olefin Metathesis
作者:Yunfei Zhang、Janis Jermaks、Samantha N. MacMillan、Tristan H. Lambert
DOI:10.1021/acscatal.9b03656
日期:2019.10.4
The catalytic ring-closing carbonyl-olefin metathesis (RCCOM) of O-allyl salicylaldehydes to form 2H-chromenes is described. The method utilizes a [2.2.1]-bicyclic hydrazine catalyst and operates via a [3 + 2]/retro-[3 + 2] metathesis manifold. The nature of the allyl substitution pattern was found to be crucial, with sterically demanding groups such as adamantylidene or diethylidene offering optimal
Methoxy or methoxycarbonyl-substituted phenyl propargyl ethers were subjected to Claisen rearrangement either in the absence or in the presence of CsF. Substituent effect on the cyclization is discussed.
Indium-catalyzed intramolecular hydroarylation of aryl propargyl ethers
作者:Lorena Alonso-Marañón、M. Montserrat Martínez、Luis A. Sarandeses、José Pérez Sestelo
DOI:10.1039/c4ob02033b
日期:——
Indium(III) halides catalyze efficiently the intramolecularhydroarylation (IMHA) of aryl propargyl ethers. The reaction proceeds regioselectively with terminal and internal alkynes bearing electron-rich and electron-deficient substituents in the benzenes and alkynes affording only the 6-endo dig cyclization product. Additionally, a sequential indium-catalyzed IMHA and palladium-catalyzed Sonogashira