ChemInform Abstract: Hexaalkylguanidinium Salts as Ionic Liquids — Applications in Titanium and Aluminium Alcoholate Assisted Synthesis.

Abstract

Hexaalkylguanidinium Salts as Ionic Liquids -Applications in Titanium andAluminium Alcoholate Assisted Synthesis. -Guanidinium-based ionic liquids containing titanium or aluminum alcoholate are successfully applied as Lewis-acidic catalytic media for some dehydrating cyclocondensation reactions: i. e., lactamization of -aminocarboxylic acids, direct amidation of carboxylic acids, synthesis of oxazolines from carboxylic acids and 2-aminoethanol, lactonization of 6-hydroxyhexanoic acid, and Paal-Knorr synthesis of pyrroles. -(ARKHIPOVA, M.; EICHEL, S.; MAAS*, G.; RSC Adv. 4 (2014) 99, 56506-56517, http://dx.

Direct amidation of non-activated phenylacetic acid and benzylamine derivatives catalysed by NiCl 2

“…In the last 10 years, catalytic direct amidations catalysed by organo-boron derivatives have emerged, and lots of catalytic protocols have been discovered so far for the direct amidation of carboxylic acids and amines, and works on these topics were already well reviewed by Figueiredo et al [16]. Although underdeveloped, metal-catalysed direct amidations have received increasing attention in the past few years, most of this attention being focused on early transition metal complexes involving titanium complexes such as Ti(OiPr) 4 , Ti(OBn) 4 and TiCl 4 [17]; zirconium salts or complexes such as ZrCl 4 , Zr(OEt) 4 and Zr(Cp) 2 Cl 2 [18,19]; Hf(Cp) 2 Cl 2 [20] and others [21,22]. Some of them showed good efficiency for amidations; however, the drawbacks of these metal catalysts are their insensitivity to water and air or difficulty to be recycled.…”