Synthesis of trans-4,5-Bis-dibenzylaminocyclopent-2-enone from Furfural Catalyzed by ErCl₃·6H₂O

Abstract

An experiment exploring the chemistry of the carbonyl group for the one-step synthesis of trans-4,5dibenzylaminocyclopent-2-enone is described. The reaction of furfural and dibenzylamine in the environmentally friendly solvent ethanol and catalyzed by the Lewis acid ErCl 3 •6H 2 O afforded the product in high yield (79−97%) with high purity by simple filtration. This experiment can be performed during a 3 h class, and requires only basic glassware without an anhydrous or inert atmosphere. It is suitable for use in introductory organic chemistry laboratories, where the purity of the product can be determined, using simple techniques such as TLC analysis and melting point measurement, as well as for more advanced classes allowing the consolidation of important reactivity features of the carbonyl group and the interpretation of the 1 H NMR spectrum.

Silica-Supported Copper for the Preparation of trans-4,5-Diamino-Cyclopent-2-Enones under Continuous Flow Conditions

“…Cyclopentenone (CP) is a highly versatile motif that can be used as an intermediate for the preparation of several natural occurring products. − Among the various methodologies for the formation of CP, the transformation of biomass derivatives furfural − and 5-hydroxymethylfurfural , to CP via a cascade furan ring-opening/Nazarov electrocyclization has been thoroughly studied. The condensation of furfural with secondary amines to yield trans- 4,5-diamino-cyclopent-2-enones (DCP) has been systematically studied and is known to be promoted under homogeneous conditions (Figure ) by lanthanides ,− and copper trifluoromethanosulfonate (Cu­(OTf) 2 ); under heterogeneous conditions by ErCl 3 . 6H 2 O immobilized on silica, metal–organic frameworks (Fe-MIL-100), and montmorillonite K10 23, ; and also in the absence of catalysts by microwave irradiation in water (MW, 60 °C). …”

Preparation of Aminals under Continuous Flow Conditions

“…Aminals are a class of compounds easily accessible from the condensation of aldehydes with secondary amines, which are two fundamental functional groups in the Organic Chemistry curriculum. − Despite aminals being known for decades, organic chemists have focused solely on their use as protection of aryl aldehydes prior to lithiation. − Recent innovative reports on the use of aminals have emerged, , and we described a method to prepare those compounds under mild conditions by using copper catalysts, thus paving the way for new methodologies employing aminals as key synthons …”

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

“…Lanthanide chloride immobilized on silica as ErCl 3 . 6H 2 O [62,63] was proposed for the preparation of diaminocyclopent-2-enones from furfural, but the procedure involved the use of organic solvents to obtain a selectivity of above 83%. Recently, a metal-organic framework (MOF) showed a higher activity than the homogeneous catalyst, but the system conditions under which the reaction occurred, such as the use of organic solvents under an N 2 atmosphere, were crucial in determining the course of the performance [64].…”