Expeditious, Metal-Free, Domino, Regioselective Synthesis of Highly Substituted 2-Carbonyl- and 2-Phosphorylfurans by Formal [3+2] Cycloaddition
Résumé
-Functionalized furans are very easily synthesized by exploiting the dual nucleophilic character of 1,2-dicarbonyls and the dual electrophilic properties of (2-chloro-2-nitroethenyl)benzenes in a one-pot, formal [3+2] cycloaddition. Using a base (DBU), the desired trisubstituted heterocycles were formed rapidly (10-30 min) in good to excellent yields (51-92 %), and this versatile, metal-free methodology was applied to the synthesis of 2-acyl- and 2-carboalkoxyfurans and furan-2-carboxamides. Additionally, by using 2-ketophosphonate derivatives as dinucleophiles, the corresponding 2-phosphorylfurans were formed in good yields (53-74 %).