1. Boroxine template for macrocyclization and postfunctionalization
Kosuke Ono, Satoru Onodera, Hidetoshi Kawai Chem Commun (Camb). 2022 Nov 10;58(90):12544-12547.doi: 10.1039/d2cc04691a.
A novel synthetic strategy for large macrocyclic molecules using boroxine formation was developed. For this, the threefold intramolecular olefin metathesis of 3,5-bis(alkenyloxy)phenylboroxines with various lengths of alkenyl chains, formed by the dehydration of the corresponding boronic acid substrates, together with treatment with pinacol, was used to produce 39-, 45-, and 51-membered macrocyclic compounds with three boronate units. The boroxine moiety functions as a covalent template but can also be used to postmodify the macrocycle. Boroxine-templated macrocyclization implemented in this way does not require the addition of template molecules and simplifies the synthetic procedure.
2. Bis-Boronic Acid Liposomes for Carbohydrate Recognition and Cellular Delivery
Megan L Qualls, Hannah Hagewood, Jinchao Lou, Samuel I Mattern-Schain, Xiaoyu Zhang, Deidra J Mountain, Michael D Best Chembiochem. 2022 Nov 4;23(21):e202200402.doi: 10.1002/cbic.202200402.Epub 2022 Sep 21.
Liposomes are effective therapeutic nanocarriers due to their ability to encapsulate and enhance the pharmacokinetic properties of a wide range of drugs and diagnostic agents. A primary area in which improvement is needed for liposomal drug delivery is to maximize the delivery of these nanocarriers to cells. Cell membrane glycans provide exciting targets for liposomal delivery since they are often densely clustered on cell membranes and glycan overabundance and aberrant glycosylation patterns are a common feature of diseased cells. Herein, we report a liposome platform incorporating bis-boronic acid lipids (BBALs) to increase valency in order to achieve selective saccharide sensing and enhance cell surface recognition based on carbohydrate binding interactions. In order to vary properties, multiple BBALs (1 a-d) with variable linkers in between the binding units were designed and synthesized. Fluorescence-based microplate screening of carbohydrate binding showed that these compounds exhibit varying binding properties depending on their structures. Additionally, fluorescence microscopy experiments indicated enhancements in cellular association when BBALs were incorporated within liposomes. These results demonstrate that multivalent BBALs serve as an exciting glycan binding liposome system for targeted delivery.
3. Bis-Boric Acid-Mediated Regioselective Reductive Aminolysis of 3,4-Epoxy Alcohols
Wei Tang, Chuan Wang J Org Chem. 2022 Nov 18;87(22):15653-15660.doi: 10.1021/acs.joc.2c01878.Epub 2022 Nov 3.
Herein we report a bis-boric acid-mediated regioselective reductive aminolysis of 3,4-epoxy alcohols, providing new access to prepare amino diols in high diastereofidelity directly starting from nitroarenes. Notably, this step-economical process is enabled by the essential dual function of bis-boric acid, which is engaged initially in the 4,4'-bipyridine-catalyzed reduction of nitro compounds as the reductant and subsequently promotes the ring opening reaction of 3,4-epoxy alcohols with the in situ-generated anilines.
