Non classé

Unsymmetrical (hetero)aryl selenides and tellurides have been prepared in satisfactory yields from arylazo sulfones under visible light driven, photocatalyst‐ and metal‐free conditions.

A protocol for the visible light driven preparation of unsymmetrical (hetero)aryl selenides and tellurides is described herein. The method exploits the peculiar photoreactivity of arylazo sulfones that act as thermally stable, precursors of aryl radicals under both photocatalyst‐ and additive‐free conditions. The method developed shows an impressive versatility (more than fifty compounds isolated).

Spirocyclopropyl oxindole comprising spiro‐fusion of 2‐oxindole with cyclopropane unit is a versatile organic framework. The present review highlights the detailed chemistry of spirocyclopropyl oxindole core. Various synthetic approaches to afford spirocyclopropyl oxindoles have been discussed followed by their applications in ring‐opening/expansion reactions.

Spirocyclopropyl oxindole represents an emerging framework by unique amalgamation of versatile 2‐oxindole motif and highly strained cyclopropane unit. This scaffold is remarkable for its diverse medicinal and synthetic applications. The present review delivers a comprehensive overview of the strategies to afford spirocyclopropyl oxindoles and their potential synthetic transformations. The syntheses of spirocyclopropyl oxindoles have been described based on the type of precursors, including isatin, 3‐alkenyl oxindole, diazooxindole, oxindole, and 3‐chlorooxindole. Besides, the utility of different cyclopropanation reagents like sulfur ylide, MBH‐carbonate, carbenoid, vinyl selenone, etc. have also been emphasized. Furthermore, various ring‐expansion/opening reactions of spirocyclopropane oxindoles using dipolarophiles/nucleophiles have critically been illustrated.

An optimized protocol for the preparation of fluorine‐containing acyclic enones, which react with secondary amines to form fluorinated 3‐amino‐cyclopent‐2‐enones via 4‐amino‐2,3‐dihydrofuran‐2‐ols was developed. A plausible mechanism is proposed.

An optimized protocol for the preparation of fluorine‐containing acyclic enones, which are promising building blocks for the preparation of a large variety of fluorinated compounds was developed. These enones easily react with secondary amines to form fluorine‐containing 3‐aminocyclopent‐2‐enones via 4‐amino‐2,3‐dihydrofuran‐2‐ols. The peculiar mechanism involving an intramolecular electrocyclization as a key step is proposed.

The metal‐free selective and diverse synthesis of three distinct sets of isoindolinones from 2‐alkynylbenzoic acids and amines in a controlled manner is reported. This process features metal free, readily available starting materials, broad substrate scope, excellent selectivity, good to high yields, good functional group tolerance, simple operation, high bond‐forming efficiency, and step economy.

The metal‐free selective and diverse synthesis of three distinct sets of isoindolinones from 2‐alkynylbenzoic acids and amines has been achieved in a reaction‐condition‐controlled manner. This method exhibits valuable advantageous features such as available starting materials, broad substrate scope, excellent selectivity, good to high yields, good functional group tolerance, simple operation, high bond‐forming efficiency, and step economy, thus providing a convenient and efficient access to a variety of heterocyclic compounds incorporating the bioactive isoindolinone motif.

An azidopyran was coupled through a CuAAC reaction with oligoalkynes to provide multivalent carbohydrate mimetics with flexible or rigid core elements. Preliminary SPR measurements indicate that an O‐sulfated C₆₀‐derived dodecavalent compound may be an excellent ligand of L‐ and P‐selectins (IC₅₀ values in low nM range).

Starting from an enantiopure 3‐azido‐substituted pyran derivative and various oligo‐alkynes a series of multivalent 1,2,3‐triazole‐linked carbohydrate mimetics was synthesized. The copper‐catalyzed Huisgen–Meldal‐Sharpless cycloaddition (CuAAC) served as key coupling reaction. Cu/C in the presence of triethylamine proved to be a good catalytic system in most cases. Tri‐, tetra‐, hexa‐, and octavalent compounds with typical rigid or flexible core units were prepared. The most complex compound contains a C₆₀‐fullerene center leading to a dodecavalent carbohydrate mimetic. Only a few of the multivalent target compounds could be converted into pure O‐sulfated derivatives that are required for their evaluation as L‐ and P‐selectin ligands. Nevertheless, preliminary experiments suggest that the dodecavalent C₆₀‐derived compound may be a promising ligand of these biologically important proteins with IC₅₀ values in the low nanomolar range.