Aspects of the formation and use of stenhouse salts and related compounds

Montmorillonite K10-Catalyzed Solvent-Free Conversion of Furfural into Cyclopentenones

“…In fact, the presence of excess amines leads to the formation of an enolic intermediate that successively yields the respective 2,4-cyclopentenone derivative. The mechanism of this reaction was proposed by Lewis and Mulquiney [82].…”

Montmorillonite K10-Catalyzed Solvent-Free Conversion of Furfural into Cyclopentenones

“…Adding amine (0.2 mmol) to the reaction mixture at room temperature without microwave irradiation, we observed that the product 4,5-dimorpholino cyclopentenone is converted into the respective 2,4 cyclopentenone derivative after only one hour. The mechanism of reaction is proposed by Lewis and Mulquiney [74].…”

Synthesis and Applications of Stenhouse Salts and Derivatives

“…First reported in 1850, Stenhouse salts (SSs) result from the furan ring‐opening reaction upon condensation of furfurals and amines (Scheme ). These salts are named after J. Stenhouse, who first described the formation of 1 a , the product of reacting aniline with a furfural‐containing crude oil obtained upon acidic treatment of various vegetable plants . In fact, this strategy allows for the identification of furfurals in food products due to the intense color of these salts as a result of its conjugated triene structure .…”

“…These salts are named after J. Stenhouse,w ho first described the formation of 1a,t he product of reactinga niline with af urfural-containing crude oil obtained upon acidic treatment of various vegetable plants. [1][2][3] In fact, this strategy allows for the identification of furfurals in food products due to the intense color of these salts as ar esult of its conjugated triene structure. [4] Early studies revealed that SS undergo at hermal4 p-electrocyclization reactionu nder acidic conditions to give the corresponding colorless 4,5-diamino-2cyclopentenones 2 (4,5-diamino-CPs), which further rearrange into the thermodynamically more stable 2,4-isomer 3 (Scheme 1).…”