| Feist–Benary synthesis | |
|---|---|
| Named after | Franz Feist Erich Benary |
| Reaction type | Ring forming reaction |
| Identifiers | |
| RSC ontology ID | RXNO:0000501 |
TheFeist–Benary synthesis is anorganic reaction betweenα-halo ketones and β-dicarbonyl compounds to produce substitutedfuran compounds.[1] Thiscondensation reaction iscatalyzed byamines such asammonia andpyridine. The first step in the ring synthesis is related to theKnoevenagel condensation. In the second step theenolate displaces analkylhalogen in anucleophilic aliphatic substitution.
In place of α-haloketones, propargyl sulfonium salts can be used to alkylate the diketone.[2]
Another modification is theenantioselectiveinterrupted Feist-Benary reaction[3] with achiral auxiliary based on thecinchonaalkaloidquinine based in the presence ofproton sponge to the hydroxydihydrofuran. This type of alkaloids is also used in asymmetric synthesis in theAD-mix. The alkaloid isprotonated throughout the reaction and transfers itschirality by interaction of the acidicammonium hydrogen with the dicarbonyl group ofethyl bromopyruvate in a 5-memberedtransition state.
