Synthesis of Isocoumarins: Rhenium Complex-Catalyzed Cyclization of 2-Ethynylbenzoic Acids
摘要:
When 2-ethynylbenzoic acids were treated with a catalytic amount of a rhenium complex, such as ReCl(CO())5, 6-endo cyclization of 2-ethynylbenzoic acids proceeded with a high selectivity to give the corresponding isocoumarins in moderate to good yields.
4-Chloroisocoumarins can be conveniently prepared from 2-alkynylaryloate esters via the activation of alkynes by electrophilic chlorine, generated in situ from N-chlorosuccinimide (NCS) in the presence of 10 mol % trimethylsilyl chloride (TMSCl), which leads to 6-endo-dig-selective chlorinative annulation to give the desired products in moderate to quantitative yields. The procedure employs readily
A non‐oxidant and metal‐free strategy for synthesizing iso‐coumarin by using a continuous electrochemical microreactor to initiate an oxidative cyclization reaction of o‐(1‐alkynyl) benzoate and radicals. This efficient and clean continuous electrosynthesis method not only avoids the complicated gas protection operation and production of by‐products in the batch processes, but also help to overcome
Iodine-Mediated Solvent-Controlled Selective Electrophilic Cyclization and Oxidative Esterification of <i>o</i>-Alkynyl Aldehydes: An Easy Access to Pyranoquinolines, Pyranoquinolinones, and Isocumarins
作者:Akhilesh K. Verma、Vineeta Rustagi、Trapti Aggarwal、Amit P. Singh
DOI:10.1021/jo101526b
日期:2010.11.19
provides pyrano[4,3-b]quinolines 4a−f, via formation of cyclic iodonium intermediate Q; however, using alcohols as a solvent as well as nucleophile, o-alkynyl esters 5a−y were obtained selectively in good to excellent yields via formation of hypoiodide intermediate R. Subsequently, o-alkynyl esters were converted in to pyranoquinolinones 6a−i and isocoumarin 6j by electrophilic iodocyclization. This
Facile synthesis of sulfenyl-substituted isocoumarins, heterocycle-fused pyrones and 3-(inden-1-ylidene)isobenzofuranones by FeCl3-promoted regioselective annulation of o-(1-alkynyl)benzoates and o-(1-alkynyl)heterocyclic carboxylates with disulfides
作者:Zhen Li、Jianquan Hong、Linhong Weng、Xigeng Zhou
DOI:10.1016/j.tet.2011.12.003
日期:2012.2
Reported herein is the FeCl3-promoted intermolecular sulfoesterification of o-(1-alkynyl)benzoates with disulfides, which provides a convenient and efficient method for synthesis of 4-sulfenylisocoumarins. Various functional groups such as methoxy, halides, ester, cyano and silicon groups in the substrates are tolerated, and heterocycle-fused chalcogenylpyrones are also successfully achieved directly