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Hafnium Chloride Tetrahydrofuran Complex‐Catalyzed Diels–Alder Cycloadditions of 3‐Ethoxycarbonylcoumarins with 1,3‐Dienes under Solvent‐Free Conditions
Author(s) -
Fringuelli Francesco,
Girotti Rugiada,
Pizzo Ferdinando,
Zunino Ennio,
Vaccaro Luigi
Publication year - 2006
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200505297
Subject(s) - chemistry , tetrahydrofuran , lewis acids and bases , catalysis , chloride , solvent , diels–alder reaction , lewis acid catalysis , organic chemistry , cycloaddition , salt (chemistry) , hafnium , medicinal chemistry , zirconium
Abstract Hafnium chloride tetrahydrofuran complex (HfCl 4 ⋅2 THF) is an efficient catalyst for the Diels–Alder cycloadditions of 3‐ethoxycarbonylcoumarins 1a – c and 1,3‐butadienes 2x – z under solvent‐free conditions furnishing the corresponding cycloadducts in excellent yields. This salt is an air stable Lewis acid and therefore the reactions can be performed in air atmosphere making the procedure simple to be carried out.