The Future of Boron in Medicinal Chemistry: Therapeutic and Diagnostic Applications

Rapid Access to Highly Functionalized Alkyl Boronates by NiH-Catalyzed Remote Hydroarylation of Boron-Containing Alkenes

The direct and selective functionalization of relatively simple and readily accessible precursors to produce highly functionalized alkyl boronates is a synthetically useful process. Herein we report a NiH-catalyzed remote hydroarylation process that can, through a synergistic combination of chain walking and subsequent cross-coupling, introduce an aryl group at the adjacent carbon atom of alkyl boronates under mild conditions. By means of a preliminary experiment with moderate enantioselectivity, it was shown that an asymmetric version could also be realized.

Decarboxylative borylation

The widespread use of alkyl boronic acids and esters is frequently hampered by the challenges associated with their preparation. We describe a simple and practical method to rapidly access densely functionalized alkyl boronate esters from abundant carboxylic substituents. This broad-scope nickel-catalyzed reaction uses the same activating principle as amide bond formation to replace a carboxylic acid moiety with a boronate ester. Application to peptides allowed expedient preparations of α-amino boronic acids, often with high stereoselectivity, thereby facilitating synthesis of the alkyl boronic acid drugs Velcade and Ninlaro as well as a boronic acid version of the iconic antibiotic vancomycin. The reaction also enabled the discovery and extensive biological characterization of potent human neutrophil elastase inhibitors, which offer reversible covalent binding properties.

Disruption of motor behavior and injury to the CNS induced by 3-thienylboronic acid in mice

The scarcity of studies on boron containing compounds (BCC) in the medicinal field is gradually being remedied. Efforts have been made to explore the effects of BCCs due to the properties that boron confers to molecules. Research has shown that the safety of some BCCs is similar to that found for boron-free compounds (judging from the acute toxicological evaluation). However, it has been observed that the administration of 3-thienylboronic acid (3TB) induced motor disruption in CD1 mice. In the current contribution we studied in deeper form the disruption of motor performance produced by the intraperitoneal administration of 3TB in mice from two strains (CD1 and C57BL6). Disruption of motor activity was dependent not only on the dose of 3TB administered, but also on the DMSO concentration in the vehicle. The ability of 3TB to enter the Central Nervous System (CNS) was evidenced by Raman spectroscopy as well as morphological effects on the CNS, such as loss of neurons yielding biased injury to the substantia nigra and striatum at doses ≥200mg/kg, and involving granular cell damage at doses of 400mg/kg but less injury in the motor cortex. Our work acquaints about the use of this compound in drug design, but the interesting profile as neurotoxic agent invite us to study it regarding the damage on the motor system.