Visible light amination/Smiles cascade: access to phthalazine derivatives

Area of Science:

• Organic Chemistry
• Photocatalysis
• Synthetic Methodology

Background:

• Phthalazine derivatives are important scaffolds in medicinal chemistry and materials science.
• Efficient and versatile synthetic routes to functionalized phthalazines are highly sought after.
• Radical reactions and photoredox catalysis offer powerful tools for C-N bond formation.

Purpose of the Study:

• To develop a new cascade reaction for the synthesis of phthalazine derivatives.
• To utilize visible light photocatalysis to initiate a sequence involving radical hydroamination and Smiles rearrangement.
• To establish a mild and efficient method with broad substrate scope and functional group tolerance.

Main Methods:

• Visible light photocatalysis to generate radical intermediates.
• Cascade reaction involving radical hydroamination and subsequent radical Smiles rearrangement.
• Synthesis from readily accessible ortho-alkynylsulfonohydrazone precursors.

Main Results:

• Successful synthesis of various phthalazine derivatives in high yields.
• Demonstrated broad scope of the reaction with diverse ortho-alkynylsulfonohydrazone precursors.
• Excellent functional group tolerance under mild photoredox conditions.
• Development of a one-pot protocol from carbonyl compounds for rapid synthesis.

Conclusions:

• A novel and efficient visible light-mediated cascade reaction for phthalazine synthesis has been established.
• The methodology provides rapid access to structurally diverse phthalazine derivatives.
• This approach offers a valuable tool for the construction of complex organic molecules.