Efficient and Rapid Stereoselective Synthesis of trans-4,5-Diaminocyclopent-2-enones by Acidic Ionic Liquid under Solvent-free Conditions

Abstract

Acidic ionic liquid 1-methylimidazolium tetrafluoroborate [HMim]+[BF4]−, was successfully employed as a reusable catalyst for the reaction of furfural and secondary amines to yield 4,5-diaminocyclopent-2-enones exclusively as trans diastereomer in the absence of solvent. The inherent Brønsted acidity and high polarity of ionic liquid resulted in the significant enhancement in the reaction rate.

Synthesis and Applications of Stenhouse Salts and Derivatives

“…Under this reactionc onditions, several CPs wereo btained in high yields after short reaction times (up to 98 %y ield in around5min). [10] In 2013, Yu,W ang and co-workersr eported the use of p-toluenesulfonamide catalysis, which allowed the reactiono ff urfural and secondary amines to be performed at 80 8Cu nder metal-free conditions. [11] Therein, the reaction of the N-sulfonylimine intermediate with severala mines was also described.…”

“…In 2009, Venkateswarlu and co‐workers reported the use of the acidic ionic liquid 1‐methylimidazolium tetrafluoroborate as reusable reaction medium. Under this reaction conditions, several CPs were obtained in high yields after short reaction times (up to 98 % yield in around 5 min) . In 2013, Yu, Wang and co‐workers reported the use of p ‐toluenesulfonamide catalysis, which allowed the reaction of furfural and secondary amines to be performed at 80 °C under metal‐free conditions .…”

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

“…In this context, furfural is important biomass compound derived and used to synthesize different bio-products [50]. The cyclization rearrangement can be realized by different Lewis acids as metallic compounds [51], triflate [52][53][54], metal chloride [55] in ionic liquids [56] or using green media as water [57] or deep eutectic solvents [58].…”

Novel Role of p-Toluenesulfonamide in the Preparation of 4,5-Diaminocyclopent-2-enones

“…4 Ramesh and Venkateswarlu also described a useful method to synthesize 1 in [HMim] + [BF 4 ] -, which worked as catalyst as well as reusable reaction medium. 5 N-Tosylamino group as a leaving group toward a range of nucleophiles facilitated by various kinds of Brønsted or Lewis acids has attracted much attention. 6 As shown in Scheme 1, iminium ion 2 was an important intermediate for the subsequent Michael addition, ring opening and closing reaction.…”

“…6 As shown in Scheme 1, iminium ion 2 was an important intermediate for the subsequent Michael addition, ring opening and closing reaction. 5,7,8 In our continuing efforts on reactions of p-toluenesulfonamide as a leaving group, 9 we were interested in the use of p-toluenesulfonamide on the formation of 1 and with a hypothesis that p-toluenesulfonamide can stabilize 2 in the form of 2′ (Scheme 1). N-(Furan-2-ylmethylene)-4-methylbenzenesulfonamide (3a′) was used first instead of 2-furaldehyde (3a) to react with morpholine (4a).…”