Amino Acid-Promoted Synthesis of 2H-Chromenes

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Green Chemistry

Background:

• The 2H-chromene scaffold is prevalent in biologically active natural products and privileged in drug discovery.
• Current synthetic methods often rely on less sustainable catalysts.

Purpose of the Study:

• To develop a sustainable and efficient method for synthesizing 2H-chromenes using biobased catalysts.
• To explore the use of aliphatic amino acids as catalysts in the synthesis of medicinally significant compounds.

Main Methods:

• Utilized aliphatic amino acids, specifically l-alanine, to catalyze the reaction between nucleophilic phenols (resorcinols) and enals.
• Conducted reactions under heating in solvents like toluene or propyl acetate.
• Investigated the scalability and substrate scope of the developed synthetic route.

Main Results:

• Achieved efficient synthesis of 2H-chromenes using l-alanine as a catalyst, demonstrating a sustainable alternative to traditional amine catalysts.
• The reaction exhibited broad substrate scope and was successfully scaled up.
• Synthesized several natural products, including Radula chromenes and cannabichromene, in a single step from readily available starting materials, with multigram scale production achieved for some.

Conclusions:

• Aliphatic amino acids are effective, sustainable catalysts for the synthesis of 2H-chromenes.
• The developed method offers a scalable and versatile route for accessing medicinally important natural products.
• This approach aligns with green chemistry principles by employing biobased catalysts.