Traceless Solid-Phase Synthesis of Trisubstituted Quinazolines

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Synthetic Chemistry

Background:

• Quinazolines are a vital heterocyclic scaffold in medicinal chemistry, exhibiting diverse biological activities.
• Developing efficient and scalable synthetic routes for substituted quinazolines remains an active area of research.
• Polymer-supported synthesis offers advantages in purification and potential for automation.

Purpose of the Study:

• To develop a traceless polymer-supported synthesis for 4-benzoylquinazolines.
• To utilize readily available starting materials for efficient scaffold construction.
• To achieve moderate-to-high yields and purities of the target compounds.

Main Methods:

• A polymer-supported strategy was employed using Fmoc-α-amino acids, 2-nitrobenzenesulfonyl chlorides, and α-bromoacetophenones.
• Base-catalyzed rearrangement of acyclic intermediates led to resin-bound dihydroquinazoline-2-carboxylic acids.
• Cleavage from the resin with trifluoroacetic acid, followed by base-mediated decarboxylation, afforded the final products.

Main Results:

• The developed method successfully synthesized 4-benzoylquinazolines.
• The synthesis involved C-C and N-N bond formation, ring expansion, and decarboxylation steps.
• Moderate-to-high yields and purities of the target quinazolines were obtained.

Conclusions:

• A traceless polymer-supported synthesis of 4-benzoylquinazolines has been successfully established.
• The method is efficient, uses accessible building blocks, and provides good product yields and purity.
• This approach offers a valuable tool for the synthesis of quinazoline derivatives.