Enantioselective Phase-Transfer-Catalyzed Synthesis of Spirocyclic Azetidine Oxindoles

Area of Science:

• Medicinal Chemistry
• Organic Synthesis
• Catalysis

Background:

• Spirocyclic motifs are attractive in drug discovery.
• Spiro-3,2′-azetidine oxindoles combine key pharmacophores.
• Their enantioselective synthesis remains underexplored.

Purpose of the Study:

• To develop an enantioselective synthesis of spiro-3,2′-azetidine oxindoles.
• To utilize a novel chiral phase-transfer catalyst for this transformation.
• To provide access to enantioenriched medicinally relevant compounds.

Main Methods:

• Intramolecular C-C bond formation.
• Utilized a novel SF5-containing chiral cation phase-transfer (PT) catalyst.
• Phase-transfer catalysis for asymmetric induction.

Main Results:

• Achieved enantioselective synthesis of spiro-3,2′-azetidine oxindoles with up to 98% enantiomeric excess (er).
• Demonstrated facile elaboration and deprotection of products to medicinally relevant compounds.
• Control experiments indicated an interfacial PT mechanism.

Conclusions:

• The developed method provides efficient access to enantioenriched spiro-3,2′-azetidine oxindoles.
• The novel chiral PT catalyst is effective for asymmetric induction.
• This work expands synthetic strategies for complex spirocyclic pharmacophores.