Pinacolborane-assisted superacid organocatalysis enabled direct access to cytotoxic alkyl N-Cbz amines

Abstract

α-Secondary alkyl amines are structural motifs frequently encountered in a wide variety of natural products and pharmaceuticals. The N-benzyloxycarbonyl (Cbz) compound is a widely used precursor, acknowledged for its efficacy in implementing a masked amine strategy to access a privileged moiety. Although reductive amination is conducted as a crucial portion of the pharmaceutical industry, direct catalytic access to alkyl Cbz-amine is still rare due to the low reactivity of carbamate. Here, we show a superacid organocatalyst enabled direct access to bioactive Cbz-protected α-secondary alkyl amines using general ketones as the starting material. Through the highly selective and robust catalytic process, a wide substrate scope including drug precursor scaffolds in preparative scalability (up to >99% yield) with practical pharmaceutical syntheses is achieved. The obtained N-Cbz products are found to possess strong cytotoxicities in in vitro bioactivity evaluations, indicating their potential as promising candidates for new anticancer drug discovery. © 2024 The Author(s)