BODIPYS in Multicomponent Reactions. Synthesis of BODIPY-4H-Pyran Hybrids

Area of Science:

• Organic Chemistry
• Materials Science

Background:

• Boron-dipyrromethene (BODIPY) dyes are valuable fluorophores.
• Developing efficient synthetic routes for functionalized BODIPY derivatives is crucial for materials applications.

Purpose of the Study:

• To synthesize novel formyl-substituted BODIPY dyes.
• To explore the synthesis of highly substituted 4H-pyranes using these BODIPY derivatives via multicomponent reactions (MCR).
• To investigate the impact of conventional heating versus ultrasound activation on MCR efficiency and product yields.

Main Methods:

• Liebeskind-Srogl (LSCC) and Suzuki cross-coupling reactions were used for BODIPY synthesis.
• Multicomponent reactions (MCR) involving formyl-BODIPY derivatives, malononitrile, ethyl acetoacetate, and ammonium hydroxide were performed.
• Conventional heating (Method A) and ultrasound-activation (Method B) were compared for MCR.

Main Results:

• Ten formyl-substituted BODIPY dyes were synthesized in high yields (64-98%).
• Nine 4H-pyranes were prepared via conventional heating (25-72% yield).
• Six 4H-pyranes were prepared using ultrasound-activation, showing improved yields (35-64%) and reduced reaction times.
• The synthesized 4H-pyranes exhibited moderate fluorescence quantum yields (0.61-5.67%) and strong chromophore behavior (log εmax = 3.94-4.91 M⁻¹ cm⁻¹).
• A tetraarylBODIPY derivative showed red-shifted absorption and emission (627 nm and 718 nm).

Conclusions:

• Efficient synthesis of formyl-BODIPY dyes and their subsequent conversion to substituted 4H-pyranes was achieved.
• Ultrasound-activation offers a more efficient method for MCR synthesis of these compounds.
• The photophysical properties, including fluorescence and chromophore behavior, were characterized, indicating potential applications in materials science.