Acid zeolites as catalysts in organic reactions. Highly selective condensation of 2-alkylfurans with carbonylic compounds

Condensation of 2-(3-acetoxypropyl)furan and 2-methylfuran with a series of aliphatic and aromatic carbonyl compounds, including formaldehyde, acetaldehyde, hexanal, cinnamaldehyde, benzaldehyde, anisaldehyde and acetone has been carried out in the presence of acid zeolites of medium and large pore size at different reaction temperatures. While H-ZSM-5 and H-MOR exhibited lower activity, we have found that tridirectional large pore zeolites Y and β are very convenient catalysts. In some cases, total conversion with complete selectivity could be achieved under our experimental conditions. Sulfuric acid was less active and selective for this type of Friedel-Crafts condensations. The resulting gem difurylalkanes with 3-hydroxypropyl substituent at the 2 position of the furan ring can be precursors of bis-spiroketals with potential activity as juvenile hormone antagonist for the Mediterranean fly.