Synthesis of Imidazolidin-2-ones and Imidazol-2-ones via Base-Catalyzed Intramolecular Hydroamidation of Propargylic Ureas under Ambient Conditions

New multicomponent reactions in water: a facile synthesis of 1,3-dioxo-2-indanilidene-heterocyclic scaffolds and indenoquinoxalines through reaction of ninhydrin-malononitrile adduct with diverse N-binucleophiles

We report here a highly efficient green approach for the synthesis of imidazolidin-2-ylidene-indenedione, pyrimidine-2-ylidene-indenedione and indenoquinoxaline derivatives through the one-pot three-component reaction between ninhydrin, malononitrile and various diamines in water medium under catalyst-free conditions. High yields (73-98%) of the target products were achieved with short reaction times at room temperature. Simple workup, no column chromatography, good to excellent yields, rapid reaction and green solvent are the prominent advantages of this protocol.

Highly Efficient Darzens Reactions Mediated by Phosphazene Bases under Mild Conditions

The highly basic and poorly nucleophilic phosphazene base P1 -t-Bu promotes the Darzens condensation of α-halo esters with aromatic aldehydes affording α,β-epoxy esters in nearly quantitative yields under mild conditions and in short reaction times. The more basic P4 -t-Bu phosphazene was found useful with low reactivity aldehydes. These reactions can be performed in aprotic organic solvents of low polarity, thus minimizing the hydrolysis of α,β-epoxy esters which often accompanies the base-promoted Darzens condensations.

Computational study on N-triflylphosphoramide-catalyzed enantioselective hydroamination of alkenyl thiourea

The mechanism of the enantioselective intramolecular hydroamination of alkenyl thiourea catalyzed by chiral binaphthol N-triflylphosphoramide (NPTA) was investigated using density functional theory calculations. This study reveals the details of the hydrogen bonding mode between NPTA and the substrate and indicates the importance of the dual hydrogen binding properties of the thiourea moiety for the reactivity and stereoselectivity of the hydroamination.

Carboxylative Cyclization of a Propargylic Amine with CO2 Catalyzed by a Silica-Coated Magnetite

By employing a silica-coated magnetite as a catalyst, a silica-catalyzed carboxylative cyclization of propargylic amines with carbon dioxide (CO₂) proceeded to afford the corresponding 2-oxazolidinones. Moreover, after the reaction, the silica-coated magnetic catalyst was readily recovered by use of an external magnet and could be reused up to six times without deactivation.

Synthesis of enantiomerically enriched 4,5-disubstituted N-aminoimidazol-2-one (Nai) peptide turn mimics

N-Aminoimidazolone (Nai) peptide mimics were synthesized with minimal epimerization by base-promoted 5-endo-dig cyclization of aza-propargylglycine dipeptide acids and hydrazides followed by olefin migration. 5-Position functionalization using Mannich amino methylation and Vilsmeier–Haack formylation has given access to a set of restrained side chain analogs of Asp, Dab, and Hse residues for mimicry of turn form and function.

PdI2 as a Simple and Efficient Catalyst for the Hydroamination of Arylacetylenes with Anilines

The hydroamination reaction is a convenient alternative strategy for the formation of C–N bonds. Herein, we report a new versatile and convenient protocol for the hydroamination of arylacetylenes with anilines using palladium iodide in the absence of any added ligand as catalyst. Mild conditions, excellent regio- and stereoselectivity, and high functional group tolerance are the main features of this methodology. A subsequent reduction step gives access to a wide variety of secondary aromatic amines.