The reaction of furan with α, β-unsaturated carbonyl dienophiles catalyzed by K10 montmorillonite in the absence of organic solvents produces the corresponding Diels-Alder adducts and, in the case of methyl vinyl ketone, Michael-type products, under much milder conditions than the conventional protocols. The results are consistent with acid catalysis on the clay surface. Acrylates gave lower yields and/or decomposition products. The reaction ...
[Jurczak, Janusz; Belniak, Stanislaw; Kozluk, Tomasz; Pikul, Stanislaw; Salanski, Piotr Bulletin of the Polish Academy of Sciences, Chemistry, 1984 , vol. 32, # 3-6 p. 135 - 141]