Recent advances in the synthesis of biologically active spirooxindoles

Methyl isocyanide as a convertible functional group for the synthesis of spirocyclic oxindole γ-lactams via post-Ugi-4CR/transamidation/cyclization in a one-pot, three-step sequence

The synthesis of spiro[indoline-3,2'-pyrrole]-2,5'(1'H)-diones and spiro[indoline-3,2'-pyrrolidine]-2,5'-diones, via a post-Ugi-domino transamidation/cyclization sequential process, has been achieved in three sequential steps utilizing a one-pot reaction protocol. The variation in carboxylic acid substrates allows for the generation of new chiral racemic quaternary carbon centers under basic conditions providing molecular diversity and a small library of spirocyclic oxindoles.

Substituted spirooxindole derivatives as potent anticancer agents through inhibition of phosphodiesterase 1

Spirooxindole is a promising chemo therapeutic agent. Possible targets include cancers of the liver, prostate, lung, stomach, colon, and breast. Here, we demonstrate a one-pot three-component reaction via a [3 + 2] cycloaddition/ring contraction sequence of a dipolarophile (activated alkene) with in situ-generated azomethine ylide (1,3-dipoles) without the use of any catalyst. The reaction provides efficient access to synthetically useful and biologically important spirooxindoles in high yield (69-94%) with high diastereoselectivity. The synthesized compounds were subjected to cytotoxicity evaluation using colorectal cancer (HCT-116), hepatocellular carcinoma (HepG2), and prostate cancer (PC-3) cells. Compounds 4i, 4j, and 4k showed potent cytotoxic activity and high selectivity against HCT-116 cells when compared to cisplatin. Meanwhile compound 4d retained high cytotoxic activity and selectivity against HepG2 and PC-3 cells in comparison to cisplatin. The mechanism of compound 4d was further studied using phosphodiesterase 1 enzyme and showed 74.2% inhibitory activity. A possible binding mode for compound 4d to PDE-1 was investigated by molecular modeling using OpenEye software. Pose predictions for the active compounds were demonstrated by ROCS alignments. Compound 4d has a special geometry and differs from other active compounds.

A Facile One-Pot Construction of Succinimide-Fused Spiro[Pyrrolidine-2,3'-Oxindoles] via 1,3-Dipolar Cycloaddition Involving 3-Amino Oxindoles and Maleimides

Increasing interests have been invested in the development of synthetic strategies toward the construction of spiro[pyrrolidine-2,3'-oxindole], which is the core structural skeleton in some compounds with diverse biological activities. In this work, an efficient diastereoselective 1,3-dipolar cycloaddition reaction of azomethine ylides generated in situ from 3-amino oxindoles and aldehydes with maleimides has been described. The protocol provides a facile and efficient access to structurally diverse succinimide-fused spiro[pyrrolidine-2,3'-oxindole] compounds in good to high yields (up to 93%) with moderate to excellent diastereoselectivities (up to >95:5). The relative stereochemistry of cycloaddition products has been assigned by X-ray diffraction analysis.

A tethering directing group strategy for ruthenium-catalyzed intramolecular alkene hydroarylation

We report a new catalyst design for N-heterocycle synthesis that utilizes an alkene-tethered amide moiety as a directing group for aromatic C-H activation. This tethering directing group strategy is demonstrated in a ruthenium-catalyzed intramolecular alkene hydroarylation with N-aryl acrylamides to form oxindole products.

Asymmetric Catalytic Double Michael Additions for the Synthesis of Spirooxindoles

Asymmetric cascade double Michael additions to construct 2'-substituted 3,3'-spirooxindoles by using a chiral guanidine organocatalyst has been developed. A series of spirooxindole derivatives containing dihydrofuran or pyrrolidine subunits were obtained with good to excellent diastereo- and enantioselectivities. The method showed great tolerance of a number of aromatic and aliphatic alkynones. The strategy gave access to the asymmetric synthesis of (-)-salacin for the first time.

Nine-step total synthesis of (−)-strychnofoline

The asymmetric synthesis of an anti-cancer spirooxindole alkaloid, (−)-strychnofoline, has, for the first time, been accomplished in only nine steps.

Synthesis of Cholestan -3-One Derivatives Possessing a C-2 Spiro-Oxindole Substituent

A series of C-2 cholestan-3-one spiro-oxindole derivatives were prepared by the 1:3 dipolar cycloaddition reaction between the cholestan-3-one substituted by a C-2 arylidene and the azomethine ylid derived from isatin and sarcosine. The dipolarophiles were efficiently obtained by a Claisen-Schmidt reaction of cholestan-3-one and aromatic aldehydes. The structures of the products were established by a combination of NMR, high-resolution mass spectrometry (HRMS) and X-ray data analysis.

Synthesis of CF3-containing spiro-epoxyoxindoles via the Corey–Chaykovsky reaction of N-alkyl isatins with Ph2S+CH2CF3OTf−

CF₃-containing spiro-epoxyoxindoles were successfully prepared via Corey–Chaykovsky reaction of N-alkyl isatins with the ylide generated from Ph₂S⁺CH₂CF₃OTf⁻ with almost exclusive diastereoselectivity.

Catalyst-free [3 + 2] cyclization of dihydroisoquinoline imines and isatin-derived Morita–Baylis–Hillman carbonates via 1,5-electrocyclization: synthesis of tetrahydroisoquinoline-fused spirooxindoles

The incorporation of tetrahydroisoquinoline and spirooxindole frameworks has been achieved.

Facile one-pot synthesis of spirooxindole-pyrrolidine derivatives and their antimicrobial and acetylcholinesterase inhibitory activities

A library of novel spirooxindole-pyrrolidine derivatives were facilely synthesized via 1,3-dipolar cycloaddition of azomethine ylide generated from sarcosine and paraformaldehyde with various 3-methyleneoxindolines.

Asymmetric synthesis of tetrahydroisoquinoline-fused spirooxindoles as Ras-GTP inhibitors that inhibit colon adenocarcinoma cell proliferation and invasion

We report the synthesis of a library of chiral THIQ-fused spirooxindoles. The most potent compound inhibits Ras-GTP, ultimately leading to mitochondrial apoptosis.

A copper(i)-catalyzed asymmetric Mannich reaction of glycine Schiff bases with isatin-derived ketimines: enantioselective synthesis of 3-substituted 3-aminooxindoles

We have developed a copper/Ph-Phosferrox-catalyzed asymmetric Mannich reaction of Schiff bases with isatin-derived ketimines to prepare 3-substituted 3-aminooxindoles with excellent results.

Synthesis of six-membered spirooxindolesviaa chiral Brønsted acid-catalyzed asymmetric intramolecular Friedel–Crafts reaction

By means of the direct condensation of N-aminoethylpyrroles and isatins, followed by a chiral phosphoric acid-catalyzed asymmetric intramolecular Friedel-Crafts reaction, a new class of valuable chiral 3′,4′-dihydro-2′H-spiro[indoline-3,1′-pyrrolo[1,2-a]pyrazin]-2-ones bearing a quaternary carbon stereocenter were successfully synthesized in good to excellent yields and with moderate to good enantioselectivities under mild reaction conditions.

A chiral phosphoric acid-catalyzed asymmetric intramolecular Friedel–Crafts reaction for the synthesis of 3′,4′-dihydro-2′H-spiro[indoline-3,1′-pyrrolo[1,2-a]pyrazin]-2-ones.

Catalytic asymmetric synthesis of spirooxindoles: recent developments

The past four years have witnessed significant developments in the field of the catalytic asymmetric synthesis of spirooxindoles, and this feature article outlines the recent progress in this area, including the contributions of our group. This article is divided into sections according to the size and type of the generated spiro-ring fused at the C3-position of the oxindole core.

Highly diastereoselective synthesis of cyclopropane-fused spiro-pseudoindoxyl derivatives through [2 + 1] annulation of 2-ylideneoxindoles and sulfonium bromides

We developed an efficient method for diastereoselective synthesis of cyclopropane-fused spiropseudoindoxyl derivatives through [2 + 1] annulation.

A practical green approach to diversified spirochromene/spiropyran scaffolds via a glucose–water synergy driven organocatalytic system

Development of a versatile, new glucose–water organocatalytic system promoted, one pot, practical green method for the synthesis of diversified spirochromenes/spiropyrans is reported.

Thermal Hetero-Diels-Alder Reaction of Benzocyclobutenones with Isatins To Form 2-Oxindole Spirolactones

Benzocyclobutenones 1a-1g undergo cycloreversion at 150 °C in m-xylene solvent to form transient α-oxo-ortho-quinodimethanes or "ortho-quinoid ketene methides", which engage in intermolecular [4+2] cycloadditions with isatins 2a-2f to form 2-oxindole spirolactones 3a-3l. This process tolerates an array of different functional groups and substitution patterns, and is applicable to unprotected isatins 2b-2f bearing free NH-functionalities. The superior performance of isatins compared to other carbonyl based dienophiles was demonstrated and rationalized with the aid of quantum chemical calculations.

Green Method To Preparing Oxindole-Fused Spirotetrahydrofuran Scaffolds through Methanesulfonic Acid-Catalyzed Cyclization Reactions of 3-Allyl-3-hydroxy-2-oxindole in Water

Water is an ideal solvent for chemical transformations in environmentally friendly and sustainable processes. An operationally simple, metal-free, and green approach to the synthesis of oxindole-fused spirotetrahydrofurans from 3-allyl-3-hydroxy-2-oxindoles in water is described. This method requires only cheap methanesulfonic acid as a catalyst and eliminates the need of complicated reagents. This atom- and step-economical transformation is highly efficient, which provides a new approach for the construction of oxindole-fused spirotetrahydrofuran molecules with potential pharmaceutical interest.