Amine-Carbamate Self-Immolative Spacers Counterintuitively Release 3° Alcohol at Much Faster Rates than 1° Alcohol Payloads

Chembiochem. 2024 Apr 16;25(8):e202400174. doi: 10.1002/cbic.202400174. Epub 2024 Mar 14.

Abstract

Self-immolative (SI) spacers are degradable chemical connectors widely used in prodrugs and drug conjugates to release pharmaceutical ingredients in response to specific stimuli. Amine-carbamate SI spacers are particularly versatile, as they have been used to release different hydroxy cargos, ranging from 2° and 3° alcohols to phenols and oximes. In this work, we describe the ability of three amine-carbamate SI spacers to release three structurally similar imidazoquinoline payloads, bearing either a 1°, a 2° or a 3° alcohol as the leaving group. While the spacers showed comparable efficacy at releasing the 2° and 3° alcohols, the liberation of the 1° alcohol was much slower, unveiling a counterintuitive trend in nucleophilic acyl substitutions. The release of the 1° alcohol payload was only possible using a SI spacer bearing a pyrrolidine ring and a tertiary amine handle, which opens the way to future applications in drug delivery systems.

Keywords: TLR agonists; carbamates; drug delivery; prodrugs; self-immolative spacers.

MeSH terms

  • Amines*
  • Carbamates
  • Drug Delivery Systems
  • Ethanol
  • Prodrugs*

Substances

  • Amines
  • Carbamates
  • Prodrugs
  • Ethanol