Highly diastereoselective synthesis of spiro[cyclopropane-1,3′-indolin]-2′-ones via catalyst-free cyclopropanation using ethyl diazoacetate

Sulphur ylide-mediated cyclopropanation and subsequent spirocyclopropane rearrangement reactions

The efficient construction of cyclopropyl spiroindoline skeletons and the exploration of related follow-up synthetic transformations have elicited considerable interest amongst members of the chemistry community. Here, we describe a formal (2 + 1) annulation and three-component (1 + 1 + 1) cascade cyclisation via sulphur ylide cyclopropanation under mild conditions. The spiro-cyclopropyl iminoindoline moiety can be readily transformed into another medicinally interesting pyrrolo[3,4-c]quinoline framework through a novel rearrangement process.

Diastereoselective synthesis of α-dicarbonyl cyclopropanes via a lanthanide amide-catalysed reaction

Lanthanide bis(trimethylsilyl)amides, [(Me₃Si)₂N]₃Ln(μ-Cl)Li(THF)₃, were used as efficient catalysts for a one-pot reaction of α-ketoesters, dialkyl phosphite, and activated alkenes to produce α-dicarbonyl cyclopropanes in moderate to high yields. The reaction was stereoselective and the two adjacent carbonyls linked to the cyclopropane were in the cis-configuration. The high efficiency of the lanthanide amide in catalysing the reaction is the result of the cooperation between the lanthanide metal centre and the N(SiMe₃)₂ anion.

Iodine-promoted one-pot synthesis of 1,3,4-oxadiazole scaffolds via sp3 C–H functionalization of azaarenes

An efficient metal-free one-pot protocol has been developed for the construction of 1,3,4-oxadiazole derivatives via iodine-mediated oxidative amination of benzylic C–H bonds of azaarenes.

Solvent-Controlled, Tunable Domino Reaction of 3-Ylideneoxindoles with in Situ-Generated α-Aryldiazomethanes: A Facile Access to 3-Spirocyclopropyl-2-oxindole and Pyrazoloquinazolinone Scaffolds

A mild and efficient solvent-controlled, metal-free switchable 1,3-dipolar cycloaddition/ring contraction or ring expansion domino reaction of 3-ylideneoxindoles with in situ-generated α-aryldiazomethanes has been developed. This domino reaction provided a series of aryl-substituted 3-spirocyclopropyl-2-oxindoles and pyrazoloquinazolinones with excellent regio- and diastereoselectivity from common substrates under varying solvent conditions.

Lanthanide amide-catalyzed one-pot functionalization of isatins: synthesis of spiro[cyclopropan-1,3′-oxindoles] and 2-oxoindolin-3-yl phosphates

A lanthanide-catalyzed one-pot reaction using readily accessible substrates was developed affording spiro[cyclopropan-1,3′-oxindoles] in good yields and with high stereoselectivity.

A new vinyl selenone-based domino approach to spirocyclopropyl oxindoles endowed with anti-HIV RT activity

Herein, we disclose a general and flexible access to spirocyclopropyl oxindoles by a domino Michael/intramolecular nucleophilic substitution pathway with variously substituted vinyl selenones and enolizable oxindoles in aqueous sodium hydroxide solution. The spirocyclopropyl oxindole being a privileged scaffold, some of the synthesized compounds were selected for biological evaluation. Compound showed selective anti-HIV-1 activity thanks to its ability to inhibit the reverse transcriptase.

Copper(i) catalyzed diastereoselective multicomponent synthesis of spiroindolo-pyrrolidines/-imidazolidines/-triazolidines from diazoamides via azomethine ylides

Investigations of stereoselective studies on three-/four-component reactions in the presence of copper(i) thiophene-2-carboxylate as a catalyst are performed to afford spiroindolo-pyrrolidines/-imidazolidines/-triazolidines in good yields.

Synthesis of α-amino amidines through molecular iodine-catalyzed three-component coupling of isocyanides, aldehydes and amines

A facile and efficient synthetic protocol for the synthesis of α-amino amidines has been developed using a molecular iodine-catalyzed three-component coupling reaction of isocyanides, amines, and aldehydes. The presented strategy offers the advantages of mild reaction conditions, low environmental impact, clean and simple methodology, high atom economy, wide substrate scope and high yields.

Diastereoselective synthesis of spiro[cyclopropane-1,3′-indolin]-2′-ones through metal-free cyclopropanation using tosylhydrazone salts

Anticancer spiro[cyclopropane-1,3′-indolin]-2′-ones are accessible through a transition metal-free diastereoselective cyclopropanation using in situ generated diazo-compounds.