Chemically Modified Chitosan as a Biopolymer Support in Copper-catalyzed ipso-Hydroxylation of Arylboronic Acids in Water

摘要

In the past decade, copper complexes have been extensively studied and employed in organic transformations.1 Among these applications, the copper-catalyzed hydroxylation of boronic acids is considered a facile protocol for the preparation of alcohols. Noting the significant usefulness of copper-catalyzed transformation in organic synthesis, we sought to design an alternative greener pathway utilizing biopolymers and environmentally friendly reaction conditions. To achieve this aim, we were interested in utilizing chitosan generated by the deacetylation of chitin, the second-most abundant natural polysaccaharide after cellulose. Owing to its combination of unique characteristics, chitosan is used in the form of an unmodified polymer or as modified derivatives in various applications. This is especially true in the presence of readily funclionalizable primary amino groups that enable easy and effective chemical modification of the material, thereby imparting several desirable chemical and biological properties.