ZnCl 2, ZnI 2 and TiCl 4 supported on silica gel as catalysts for the Diels-Alder reactions of furan

Abstract

ZnCl 2, ZnI 2 and TiCl 4 supported on silica gel are compared with their non-supported counterparts in the reactions of furan with acrylonitrile, 2-chloroacrylonitrile and methyl acrylate. The results obtained depend on the nature of both the dienophile and the catalyst. Whereas ZnCl 2 and ZnI 2 supported on silica gel lead to very good results with both nitriles and TiCl 4 supported on silica gel cannot be used with these dienophiles, ZnCl 2 and TiCl 4 supported on silica gel are better catalysts when methyl acrylate is used as a dienophile. ZnCl 2 and ZnI 2 supported on silica gel can be recovered and reused in the reactions with nitriles, but only the first catalyst is recoverable in the reactions of methyl acrylate. ZnCl 2 supported on silica gel is the catalyst with a wider applicability in these reactions with furan.