Al(OTf)3-Catalyzed Preparation of 4-Hydroxy-3-propargylic Coumarins and Subsequent Regioselective Cyclization towards Furo- or Pyrano[3,2-c]coumarins
摘要:
An efficient and economical approach to functionalized furo[3,2-c]coumarin and pyrano[3,2-c]coumarin derivatives has been developed from 4-hydroxy-3-(prop-2-ynyl)coumarin derivatives through organocatalysis or metallo-organocatalysis. Selective 5-exo-dig' or 6-endo-dig' cyclization of the 4-hydroxy-3-(prop-2-ynyl)coumarin substrates could be achieved under organocatalytic {1,8-diazabicyclo[5.4.0]undec-7-ene} or metallo-organocatalytic (N-methylmorpholine/CuBr) conditions, respectively, to yield potentially bioactive heterocycles in excellent yields.
Alkylation of 1,3-dicarbonyl compounds with benzylic and propargylic alcohols using Ir–Sn bimetallic catalyst: synthesis of fully decorated furans and pyrroles
作者:Paresh Nath Chatterjee、Sujit Roy
DOI:10.1016/j.tet.2011.04.092
日期:2011.6
The heterobimetallic complex [Ir(COD)(SnCl3)Cl(μ-Cl)]2 catalyzes the direct substitution of hydroxyl groups in benzylic and propargylicalcohols by 1,3-dicarbonyl moiety. In 4-hydroxycoumarin, benzylation and propargylation occurs at the 3-position. Selective propargylation or allenylation takes place depending on the nature of propargylicalcohol. By applying the methodology, multi-substituted furans