Unveiling the Three-Component Phosphonylation on Alkynylaldehydes: Toolbox toward Fluorescent Molecules

Area of Science:

• Organic Synthesis
• Organophosphorus Chemistry
• Medicinal Chemistry

Background:

• Developing efficient synthetic routes for complex heterocyclic compounds is crucial.
• Introducing phosphine oxide moieties can impart unique properties to organic molecules.
• Mild reaction conditions are desirable for broader substrate scope and reduced environmental impact.

Purpose of the Study:

• To develop a regioselective tandem approach for synthesizing annulated napthyridines/isoquinolines and related structures.
• To incorporate phosphine oxide groups into diverse molecular frameworks.
• To explore the potential applications of the synthesized compounds, including their photophysical properties.

Main Methods:

• A triflate-induced tandem reaction strategy was employed.
• One-pot synthesis involving C sp3-P and C sp2-N bond formation.
• Mechanistic studies including X-ray crystallography were performed.

Main Results:

• Good to excellent yields of annulated napthyridines/isoquinolines bearing phosphine oxide groups were achieved.
• The protocol successfully synthesized functionalized organo-phosphorylated chromenes.
• Phosphino-derived sulfamethazine and sulfamethoxazole drug analogs were synthesized efficiently.
• Mechanistic studies confirmed an ionic pathway and regioselective 6-endo dig cyclization.
• Selected compounds exhibited notable fluorescence properties.

Conclusions:

• A versatile and efficient one-pot synthetic strategy for organo-phosphorylated heterocycles has been established.
• The methodology allows for the construction of complex molecules with potential pharmaceutical and material science applications.
• The synthesized compounds demonstrate promising fluorescence, warranting further investigation.