Controllable Synthesis of Polyheterocyclic Spirooxindoles and 3,3‐Bistryptophol Oxindoles via Fe(ClO 4 ) 3 ⋅ 6H 2 O‐Promoted Hetero‐Pictet‐Spengler Reaction

Ring-Opening Cyclization (ROC) of spiro-Epoxyoxindoles with Indoles/Aldehydes: An Easy Access to Polyheterocyclic spiro-Oxindoles

A simple one-pot, two-step strategy for the synthesis of three-dimensional (3D) polyheterocyclic spiro-oxindoles by Lewis-acid-catalyzed Friedel-Crafts type C-3 alkylation of indoles via regioselective nucleophilic ring opening of spiro-epoxyoxindoles, followed by p-TSA-catalyzed Pictet-Spengler reaction with aldehydes in up to 98% yield and 1.4:1 diastereomeric ratio has been developed.

Synthesis of triazole-fused tetracyclic spirooxindole derivatives via metal-free Huisgen cycloaddition

We report an efficient, metal free method for synthesizing tetracyclic spirooxindole derivatives from N-protected isatins and propargyl bromide via Huisgen cycloaddition. This simple and practicle method provides access to spirooxindoles containing five-, six-, or seven-membered rings fused to a triazole ring.

Direct synthesis of N-functionalized indoles through isomerization of azomethine ylides

An unexpected isomerization of azomethine ylides generated in situ from isatin with indoline-2-carboxylic acid has been disclosed, providing direct access to N-functionalized indole scaffolds. This protocol has good functional group tolerance and provides various 3-(1H-indol-1-yl)indolin-2-one derivatives in moderate to high yields simply by using alcohol as the solvent, with no additional additive being required.

Synthesis of Indofulvin Pseudo-Natural Products Yields a New Autophagy Inhibitor Chemotype

Chemical and biological limitations in bioactive compound design based on natural product (NP) structure can be overcome by the combination of NP-derived fragments in unprecedented arrangements to afford "pseudo-natural products" (pseudo-NPs). A new pseudo-NP design principle is described, i.e., the combination of NP-fragments by transformations that are not part of current biosynthesis pathways. A collection of indofulvin pseudo-NPs is obtained from 2-hydroxyethyl-indoles and ketones derived from the fragment-sized NP griseofulvin by means of an iso-oxa-Pictet-Spengler reaction. Cheminformatic analysis indicates that the indofulvins reside in an area of chemical space sparsely covered by NPs, drugs, and drug-like compounds and they may combine favorable properties of these compound classes. Biological evaluation of the compound collection in different cell-based assays and the unbiased high content cell painting assay reveal that the indofulvins define a new autophagy inhibitor chemotype that targets mitochondrial respiration.

Transition metal-catalyzed synthesis of spirooxindoles

Spirooxindole is a principal bioactive agent and is observed in several natural products including alkaloids. They are broadly studied in the pharmaceutical field and have a significant role in the evolution of drugs such as anti-viral, anti-cancer, anti-microbial etc. In organic chemistry, an indispensable role is presented by transition metal catalysts. An effective synthetic perspective to spirooxindoles is the use of transition metals as the catalyst. This review discusses the synthesis of spirooxindoles catalyzed by transition metals and covers literature up to 2020.