Recent Strides in the Transition Metal-Free Cross-Coupling of Haloacetylenes with Electron-Rich Heterocycles in Solid Media

Abstract

The publications covering new, transition metal-free cross-coupling reactions of pyrroles with electrophilic haloacetylenes in solid medium of metal oxides and salts to regioselectively afford 2-ethynylpyrroles are discussed. The reactions proceed at room temperature without catalyst and base under solvent-free conditions. These ethynylation reactions seem to be particularly important, since the common Sonogashira coupling does not allow ethynylpyrroles with strong electron-withdrawing substituents at the acetylenic fragments to be synthesized. The results on the behavior of furans, thiophenes, and pyrazoles under the conditions of these reactions are also provided. The reactivity and structural peculiarities of nucleophilic addition to the activated acetylene moiety of the novel C-ethynylpyrroles are considered.

Application of meso-CF3-Fluorophore BODIPY with Phenyl and Pyrazolyl Substituents for Lifetime Visualization of Lysosomes

“…2,2,2-Trifluoro-1-(5-phenylpyrrol-2-yl)ethan-1-ol 3 was obtained according to the procedure in [ 53 ]. For the synthesis of pyrrolyl-pyrazole 4 , the cross-coupling of pyrrole with benzoylbromoacetylene in solid Al 2 O 3 [ 54 , 55 , 56 ] was followed by the treatment of 2-benzoylethynylpyrrole 5 thus formed with phenylhydrazine ( Scheme 1 ). The formation of pyrrolyl-pyrazole was carried out with slight heating up to 40 °C of 2-benzoylethynylpyrrole with 1.5 ( Scheme 1 ) of phenylhydrazine in EtOH overnight.…”

Pyrrole–Aminopyrimidine Ensembles: Cycloaddition of Guanidine to Acylethynylpyrroles

“…2-Acylethynylpyrroles 1a,f – l,n – r were obtained from pyrroles and 2-acylbromoacetylenes accordingly to methodology [ 40 , 41 , 42 ]. Physico-chemical characteristics 2-acylethynylpyrroles 1a,f – l,n – r were given in [ 40 , 43 , 44 , 45 , 46 , 47 ].…”

“…2-Aminopyrimidines with pyrrole substituents represent molecular systems, which could be particularly promising for medicinal chemistry, due to the presence of two This is likely due to the fact that, until recently, alkynones with pyrrole substituents were difficult to obtain. Such compounds have become readily available owing to the discovery of the cross-coupling reaction of pyrroles with acylhaloacetylenes in the medium of solid oxides and metal salts [40][41][42], and was widely used by us in the synthesis of diverse pyrrole heterocyclic ensembles and fused heterocyclic systems [42].…”

Tosyl/pyrrolyl-capped 1,3-enynes via t-BuOK-assisted reaction of TosMIC with acylethynylpyrroles: a new feature of this popular reagent

“…In the last decade, 2-(acylethynyl)pyrroles, readily accessible by the cross-coupling of pyrroles with haloacetylenes in solid metal oxides and salts, 21 are gaining wide acknowledgment as a multifaceted platform for the design of polyfunctional pyrrole compounds of great diversity and high complexity [for a review, see ref. 22].…”