HFIP-assisted Brønsted acid-catalyzed ring opening of 1-azabicyclo[1.1.0]butane to access diverse C3-quaternary aza-azetidines and indole-azetidines.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41028741.
- Also identified by DOI 10.1038/s41467-025-63680-z and PMC identifier 12484546.
- Licence recorded as CC BY-NC-ND.
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Abstract
Nitrogen-based heterocycles represent 60% of small-molecule-approved drugs. Increasing demand for sp<sup>3</sup>-rich N-heterocyclic scaffolds as a bioisosteric replacement in drug discovery platforms has continued to drive the development of elegant methods for the synthesis of these important molecules. Among various N-heterocycles, azetidine has emerged as a valuable scaffold. Aza-azetidines, indole-azetidines, and spirocyclic azetidines with tertiary or quaternary C3-carbon make structural and/or functional parts of various important drug molecules. However, an efficient and catalytic synthetic strategy to access those important scaffolds is still missing in the literature. Herein, we report HFIP-assisted Brønsted acid-catalyzed strain-release driven ring opening of 1-azabicyclo[1.1.0]butane (ABB) to access aza-azetidines, indole-azetidines, and spirocyclic azetidines with quaternary C3-carbon in good yield. Detailed experimental and theoretical studies using DFT shed light on the reaction mechanism. We also find promising antibacterial activity in one of these indole-azetidine compounds against Staphylococcus aureus MTCC 1430.