N,O‐Iminoboronates: Reversible Iminoboronates with Improved Stability for Cancer Cells Targeted Delivery

Herein a new class of iminoboronates obtained from 2‐acetylbenzene boronic acids and aminophenols is presented. The N,O‐ligand topology enabled the formation of an additional B−O bond that locks the boron center in a tetrahedral geometry. This molecular arrangement decisively contributes to improve the construct′s stability in biocompatible conditions and retaining the iminoboronate reversibility in more acidic environments. 2‐Acetylbenzene boronic acid was reacted with a fluorescent amino‐coumarin to yield a stable and non‐fluorescent N,O‐iminoboronate. This mechanism was further used to assemble a folate receptor targeting conjugate that selectively delivered the fluorescent amino‐coumarin to MDA‐MB‐231 human breast cancer cells. Improving iminoboronate stability: A new class of iminoboronates featuring an additional B−O bond demonstrated improved stability in biocompatible conditions, while retaining the iminoboronate′s reversibility in acidic environments. This core enabled the development of a fluorescence “off–on” mechanism using a fluorescent amino‐coumarin to prepare a stable and non‐fluorescent N,O‐iminoboronate. This methodology was further used to assemble a folate receptor‐targeting conjugate that selectively delivered the fluorescent amino‐coumarin to MDA‐MB‐231 human breast cancer cells.