Application of N‐Acylimidazoles in the Claisen Condensation Reaction

Abstract

The Claisen condensation reaction is a classical method used for the formation of C−C bonds. Homo‐ and cross‐Claisen condensation reactions are usually carried out using a Ti(IV)‐based reagent at ultra‐low‐temperatures. In this report, intermediate β‐keto acyl imidazoles were synthesised using a sodium imidazolide‐catalysed homo‐ and cross‐condensation reaction of N‐acyl imidazoles performed under mild conditions and subsequently used to prepare a range of β‐keto esters and ketones via alcoholysis or hydrolysis. This method is particularly suitable for the synthesis of isotopically‐labelled acetylacetic ester compounds. N‐acyl imidazole compounds are useful reactants for the Claisen condensation reaction.

Depolymerizing Polyethylene Terephthalate (PET) via “Imidazolysis” for Obtaining a Diverse Array of Intermediates from Plastic Waste

“…The obtained symmetric TBI products are connected to the broader family of N-acyl imidazoles (Scheme 2), which are well-known exclusive electrophiles that exhibit tunable reactivity and chemical selectivity toward forming esters and amides favoring nucleophilic substitution reactions. 36,37 N-Acylimidazoles are generally produced from N,N-carbonyldiimidazole (CDI), which itself is typically obtained via the reaction of excess imidazole with phosgene (COCl 2 ). CDI is commonly used for coupling amino acids for peptide synthesis but has also been demonstrated to be a useful functionality within polymer science for synthesizing urethane and ureacontaining monomers, as explained in Scheme 2.…”

“…In this study, imidazolysis was performed without a cosolvent as the melting points of the imidazole compounds are sufficiently low to serve as both reactant and solvent. The obtained symmetric TBI products are connected to the broader family of N -acyl imidazoles (Scheme ), which are well-known exclusive electrophiles that exhibit tunable reactivity and chemical selectivity toward forming esters and amides favoring nucleophilic substitution reactions. , …”