Tunable Methacrylamides for Covalent Ligand Directed Release Chemistry

Area of Science:

• Medicinal Chemistry
• Chemical Biology
• Drug Discovery

Background:

• Targeted covalent inhibitors are crucial for drug development and chemical probes.
• A limited number of electrophiles are suitable for designing effective covalent inhibitors.
• Existing acrylamide electrophiles can lack desired reactivity or selectivity profiles.

Purpose of the Study:

• To introduce α-substituted methacrylamides as a new class of electrophiles for targeted covalent inhibitors.
• To investigate the reactivity and tunability of these novel electrophiles.
• To demonstrate their application in developing 'turn-on' probes and facilitating drug discovery screens.

Main Methods:

• Synthesis and characterization of hetero α-substituted methacrylamides.
• Evaluation of thiol reactivity and correlation with leaving group properties (pKa/pKb).
• Application in modified ibrutinib analogs for protein labeling, kinase assays, and cellular assays.
• Development of covalent ligand-directed release (CoLDR) turn-on probes (fluorescent and chemiluminescent).

Main Results:

• Hetero α-substituted methacrylamides exhibit tunable thiol reactivity via a conjugate addition-elimination mechanism.
• Modified ibrutinib analogs demonstrated comparable potency with improved selectivity.
• CoLDR probes were successfully developed for BTK, EGFR, and K-RasG12C.
• A BTK CoLDR chemiluminescent probe facilitated a high-throughput screen for inhibitors.

Conclusions:

• α-substituted methacrylamides represent a versatile new platform for targeted covalent inhibitor design.
• Their tunable reactivity and ability to form 'turn-on' probes enhance their utility in chemical biology.
• This approach offers improved selectivity and enables novel screening strategies for drug discovery.