3,4‐Dimethoxyfuran: Eigenschaften, Berechnungen und Substitutionsreaktionen

3,4‐Dimethoxyfuran: Properties, Calculations and some Substitution Reactions 3,4‐Dimethoxyfuran (3,4‐DF) is much more reactive than furan itself. We present experimental details for the synthesis of this useful compound in 50–100 g batches. 3‐4‐Dibenzyloxyfuran has also been prepared. Quantum mechanical calculations by PPP‐and CNDO‐methods analogous to furan itself gave the following information (compared with furan): enhanced negative partial charge at C(2) and C(5), higher acidity at α‐position, a stronger and at the same time inverted dipol moment. In accordance with the calculations, 3,4‐DF can easily be substituted by weak electrophilic reagents, e.g. in a typical Mannich reaction. The bis‐amino compound 8 is produced in good yields. Lithiation by butyl‐Li leads to mono‐ or di‐substituted products. The mono‐ and di‐Li‐3,4‐DF have been used for the preparation of various acylated and alkylated 3,4‐DF derivatives. By acid hydrolysis of 3,4‐DF crystalline 4‐methoxy‐3 (2H)‐furanone has been prepared.