2.5- Dimethylfuran, Diels-Alder reactions with

Diels-Alder reaction.1 The first step in a synthesis of citreoviral (5), a metabolite of Penicillium citreoviride, from 2,4-dimethylfuran (2) is a Diels-Alder reaction with 1, to give a 7 5 mixture of endo- and exo-adducts (3). Both are converted in 3 steps to the diol (4), a precursor to 5. 

Dewar thiophenes 46 and 47 are in equilibrium 47 Diels-Alder reaction of this mixture with 2.5-dimethylfuran leads to complete conversion of the mixture, but with the formation of only one product 51, derived from the reaction of isomer 47 47... 

The Diels-Alder reaction of maleic anhydride with 3,4-dimethoxyfuran affords endo- and exo-adducts at about the same rate, in contrast to furan, where the endo-isomer is the product of kinetic control. In both cases the exo-adduct is thermodynamically more stable. 3,4-Dimethoxyfuran and p-benzoquinone give the eiufo-compound (37), whereas in the reaction with 2,3-dimethyl-1,4-benzoquinone only the exo-adduct (38) was detected. The Diels-Alder adduct (40) of methyl acrylate to 2-amino-3-cyano-4,5-dimethylfuran (39) is readily... 

---