On the protonation of dibenzo-18-crown-6

Abstract  The stability constant of the dibenzo-18-crown-6·H₃O⁺ cationic complex species dissolved in nitrobenzene saturated with water has been determined from extraction experiments in the two-phase water–nitrobenzene system and from γ-activity measurements. Various structures of protonated dibenzo-18-crown-6 are discussed. Graphical abstract        

A combined extraction and DFT study on the complexation of K+ with valinomycin

Abstract  From extraction experiments in the two-phase water–nitrobenzene system and γ-activity measurements, the stability constant of protonated tetraethyl p-tert-butylcalix[4]arene tetraacetate in nitrobenzene saturated with water was determined. By using DFT calculations, the most probable structure of the tetraethyl p-tert-butylcalix[4]arene tetraacetate·H₃O⁺ complex species was derived. Graphical Abstract        

Fluorescent probe for Zn<Superscript>2+</Superscript> with light-harvesting pyrenyl groups: sensitization via intramolecular energy transfer

Abstract  Bis[N-(1-pyrenylmethyl)salicylideneaminato]zinc(II) emits intense fluorescence on excitation of the pyrenyl group. This fluorescence originates from the excited state of the salicylideneamine moiety, indicating that efficient intramolecular energy transfer takes place. The occurrence of such efficient energy transfer is accounted for by significant spectral overlap between the emission from the S₁ state of the pyrenyl group and the absorption of the salicylideneamine–zinc complex. Graphical abstract        

Synthesis of benzohetero[3, 2-<Emphasis Type="Italic">a</Emphasis>]pyrimidines using cyclic β-keto lactone as a building block

Abstract  A novel method for the synthesis of 3-(2-substituted ethyl)-2-methylbenzohetero[3,2-a]pyrimidines in high yield (80–85%) was achieved, which involves a dihydrofuranone intermediate, readily obtained from β-ketolactone to 2-aminobenzoheterocycles. The major advantage of the methodology is the high yield and product purity. Graphical Abstract        

Enantioselective synthesis of 1-arylethanediols by rhodium-catalyzed transfer hydrogenation of α-tosyloxyarylketones

Abstract  Catalytic transfer hydrogenation of α-tosyloxyarylketones mediated by a chiral rhodium complex using an azeotropic mixture of formic acid/triethylamine afforded the corresponding 1-arylethanediol monotosylates in excellent yield with high enantioselectivity. Graphical abstract        

(<Emphasis Type="Italic">S</Emphasis>)-(−)-α-Methylbenzylamine as chiral auxiliary in the synthesis of (+)-lortalamine

Abstract  (+)-Lortalamine was synthesised using (S)-(−)-α-methylbenzylamine as a chiral auxiliary. The stereochemistry of an intermediate compound was established on the basis of X-ray crystallography, allowing unambiguous assignment of the absolute configuration. Graphical abstract        

A chemoenzymatic synthesis of 3,4,5,6-tetrahydro-2H-benzo[b][1,4]-oxazocine-3,5-dione and its derivatives

Abstract  The enzymatic cyclization of phenoxyacetylcyanomethylenetriphenylphosphorane derivatives using pre-treated baker’s yeast cells, a rapid one-pot assembly of heteromacrocyclic compounds, is described. Graphical abstract        

Ethylenebis(<Emphasis Type="Italic">N</Emphasis>-methylimidazolium) ditribromide (EBMIDTB): an efficient reagent for the monobromination of 1,3-diketones and β-ketoesters

Abstract  Ethylenebis(N-methylimidazolium) ditribromide, a stable crystalline solid, is easily prepared by reaction of the corresponding dibromide salt with bromine in n-hexane. 1,3-Diketones and β-ketoesters can be brominated chemoselectively to the corresponding α-monobrominated products by using this reagent at 0–5 °C. Under the same reaction conditions, diethyl malonate, ethyl cyanoacetate, and malonitrile were monobrominated at moderate yield. Graphical abstract        

Square-planar mixed ligand nickel dithiolenes as second-order non-linear chromophores: synthesis and characterisation of [Ni(Me<Subscript>2</Subscript>pipdt)(dddt)]

Abstract  The novel [Ni(Me₂pipdt)(dddt)] complex based on the Me₂pipdt (1,4-dimethylpiperazine-3,2-dithione) and dddt (5,6-dihydro-1,4-dithine-2,3-dithiolate) ligands has been synthesised and characterised. Structural data, vibrational marker, solvatochromic behaviour of the typical absorption in the near infrared region, and approximate theoretical calculations suggest that an unbalanced electron distribution at the dithiolene core occurs in the ground and excited states. In particular, the dddt ligand gives a prevailing contribution to the HOMO, and Me₂pipdt to the LUMO. The charge-transfer character of the HOMO–LUMO transition makes this complex a potential second-order non-linear optic chromophore. Graphical Abstract        

A diol-functionalized ionic liquid: an efficient, simple, and recoverable “capture and release” reagent for aldehydes

Abstract  A new diol-functionalized ionic liquid, 2,2-bis(1-(1-methylimidazolium)methylpropane-1,3-diol hexafluorophosphate, was synthesized and applied as a facile, efficient, and recoverable “capture and release” reagent for aldehydes. This method has the advantages of homogeneous reaction, heterogeneous separation, and recyclable uses. Graphical abstract        

Interaction of push–pull <Emphasis Type="Italic">tert-</Emphasis>enamines with phenylglyoxal

Abstract  The reaction of push–pull enamines with 1,2-biselectrophilic phenylglyoxal was investigated. Phenylglyoxal was found to react depending on the structure of the push–pull enamine, affording either a hydroxyalkylation product at the methyl group or the cyclic product via participation of the methyl group and the β-carbon of the enamine. Graphical abstract        

One-step regioselective green synthesis of 2,3-mannoepoxy-β-cyclodextrin under aqueous conditions

Abstract  A simple method for the straightforward regioselective synthesis of 2,3-mannoepoxy-β-cyclodextrin, which is a valuable precursor for further functionalization of β-cyclodextrin, is achieved under aqueous conditions without any organic solvents at a moderate yield. Graphical abstract        

Novel syntheses of some new 3,4-dihydrospiro{benzimidazo[1,2-<Emphasis Type="Italic">a</Emphasis>]pyridine-3,3′-indolin}-2′-one derivatives

Abstract  2-Methylbenzimidazole 1 reacted with 3-dicyanomethylidine-1-ethyl-2-oxoindoline 2 in ethyl acetate to afford 1-amino-2-cyano-3,4-dihydro-1′-ethylspiro{benzimidazo[1,2-a]pyridine-3,3′-indolin}-2′-one 6, which was used as a key intermediate in the synthesis of fused spiropolyheterocyclic derivatives of benzimidazopyridopyrimidine and/or benzimidazonaphthyridine nucleus incorporating an indoline moiety. Graphical abstract        

A synthesis of diethyl alkylsulfanylmethylmalonates catalyzed by KOH in an ionic liquid

Abstract  1-Ethyl-3-methylimidazolium bromide was used as a green recyclable alternative to volatile organic solvents for KOH catalyzed three-component synthesis of diethyl alkylsulfanylmethylmalonates from aldehydes, diethyl malonate, and alkylthiols. Graphical Abstract  A synthesis of diethyl alkylsulfanylmethylmalonates catalyzed by KOH in an ionic liquid      

Synthesis of novel 4-(2-amino-5-thiazolyl)-pyrimidine-2-amines as potential protein kinase inhibitors

Abstract  A short and efficient sequence for the synthesis of a series of 4-(2-amino-5-thiazolyl)-pyrimidine-2-amines was developed. 1-Phenyl-2-(6-pyrimidinyl)-ethanones, obtained via Weinreb’s methodology, were used in a Hantzsch thiazole cyclization reaction, followed by introduction of the aniline moieties via nucleophilic substitution. Graphical abstract        

A one-pot synthesis of functionalized ethyl 1,3-thiazole-5-carboxylates from thioamides or thioureas and 2-chloro-1,3-dicarbonyl compounds in an ionic liquid

Abstract  A simple one-pot synthesis of functionalized ethyl 1,3-thiazole-5-carboxylates from the reaction of 2-chloro-1,3-dicarbonyl compounds with thioureas or thioamides in the presence of 1-butyl-3-methylimidazolium trifluoromethanesulfonate is described. Graphical abstract        

Polyvinylpolypyrrolidone-supported boron trifluoride: a high-loaded,polymer-supported Lewis acid for the Ritter reaction

Abstract  A Mild and efficient method for preparing amides by reaction of nitriles with benzhydrol and tertiary alcohols is described using polyvinylpolypyrrolidone-supported boron trifluoride. Selective amidation of benzhydrol in the presence of primary benzyl alcohols was also achieved. Graphical abstract        

Synthesis of imatinib: a convergent approach revisited

Abstract  A classical convergent approach for the synthesis of the anticancer drug imatinib has been substantially improved. Imatinib was assembled by coupling the amine and carboxylic acid precursors by using N,N′-carbonyldiimidazole (CDI) as a condensing agent. Both intermediates have been synthesized by novel efficient methods. Graphical abstract        

An efficient and convenient protocol for the synthesis of novel 1′H-spiro[isoindoline-1,2′-quinazoline]-3,4′(3′H)-dione derivatives

Abstract  An efficient and direct procedure for the synthesis of novel spiro[isoindoline-1,2′-quinazoline]-3,4′(3′H)-dione derivatives is described. The process employs a condensation reaction of 2-aminobenzamides and isatins in the presence of a catalytic amount of KAl(SO₄)₂.12H₂O (alum) in ethanol under reflux. Graphical Abstract        

Structure and chromotropic properties of mono- and binuclear mixed-ligand nickel(II) complexes containing 1,3-diketonate and polyamine ligands

Abstract  Mixed-ligand Ni^II complexes have been synthesized with 1,3-diketonate and bulky tri- or tetra-amine ligands. Their structures were determined by X-ray crystallography, and solvatochromic behavior was examined by UV–vis–NIR spectroscopy. Steric effects of the bulky ligands on the coordination distances and spectral properties are discussed. Graphical Abstract