A TBADT-enabled photo-induced radical cyclization pathway: concise access to functionalized oxindoles

Area of Science:

• Organic Chemistry
• Photocatalysis
• Synthetic Methodology

Background:

• Oxindoles are important heterocyclic compounds with diverse biological activities.
• Developing efficient and mild synthetic routes to functionalized oxindoles remains a key challenge in organic chemistry.

Purpose of the Study:

• To develop a novel photo-induced cascade cyclization protocol for the synthesis of diversely functionalized oxindoles.
• To explore the utility of decatungstate anion as a hydrogen atom transfer (HAT) photocatalyst in radical cascade reactions.

Main Methods:

• Utilized arylalkynamides as starting materials.
• Employed a decatungstate anion ([W10O32]4-) as a HAT photocatalyst under photoirradiation.
• Investigated a radical cascade process involving hydrogen atom transfer.

Main Results:

• Achieved a mild and general protocol for the synthesis of functionalized oxindoles.
• Successfully constructed two C-C bonds through the radical cascade pathway.
• Observed stereospecific formation of Z-indolinones when using pivaldehyde.

Conclusions:

• The developed protocol offers an efficient strategy for synthesizing complex oxindole derivatives.
• The decatungstate anion serves as a highly effective photocatalyst for this transformation.
• The reaction pathway provides insights into stereoselective synthesis using photocatalysis.