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.
Inexpensive and Efficient Synthesis of Propargylic Substituted Active Methylene Compounds Catalyzed by FeCl<sub>3</sub>
作者:Sukhendu Maiti、Srijit Biswas、Umasish Jana
DOI:10.1080/00397910903534031
日期:2010.12.22
A highlyefficient and practical method for the synthesis of propargylic substituted 1,3-dicarbonyl compounds with direct use of propargylic alcohols in the presence of inexpensive and environmentally benign FeCl3 (5 mol%) has been presented. The reaction works with varieties of substrates at room temperature without an inert atmosphere with an excellent yield. The present method can also be employed
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
Yb(OTf)3-catalyzed propargylation and allenylation of 1,3-dicarbonyl derivatives with propargylic alcohols: one-pot synthesis of multi-substituted furocoumarin
depending on the nature of propargylic alcohols. In addition, catalytic quantities of Yb(OTf)3 can also effectively promote the propargylation and allylation of 4-hydroxycoumarins at the 3-position. By applying this reaction as the key step, a multi-substituted furocoumarin can easily be synthesized in a one-pot procedure. The advantages of this method are broad scope, mild conditions, and easy handling
Condensation of propargylic alcohols with 1,3-dicarbonyl compounds and 4-hydroxycoumarins in ionic liquids (ILs)
作者:Gopalakrishnan Aridoss、Kenneth K. Laali
DOI:10.1016/j.tetlet.2011.10.021
日期:2011.12
Propargylicalcohols are activated toward 1,3-diketones by Lewis or Brønstedacidic ionic liquids (ILs) without an added catalyst, but significantly better conversions are achieved with metallic triflates [in particular Sc(OTf)3 and Ln(OTf)3] and bismuth nitrate in imidazolium ILs. The scope of this condensation reaction was investigated with a variety of propargylicalcohols and a host of acyclic
Tris(pentafluorophenyl)borane-Catalyzed Alkylation of 1,3-Dicarbonyl Compounds with Benzylic Alcohols: Access to Oxygenated Heterocycles
作者:Chada Reddy、Jonnalagadda Vijaykumar、René Grée
DOI:10.1055/s-0030-1258214
日期:2010.11
rane has found to be an effective catalyst for the alkylation of 1,3-dicarbonyl compounds using benzylicalcohols as alkylating agents. Various 1,3-dicarbonyl compounds reacted cleanly with different benzylicalcohols to provide the corresponding monoalkylated products in good yield. In addition tris(pentafluorophenyl)borane efficiently promoted the C3 alkylation of 4-hydroxycoumarins. Further, several