Design and Preparation of a Bifunctional Nanobiohybrid Catalyst by Combining Palladium and -Amylase Enzyme: Application in One-pot Chemoenzymatic Catalysis

A chemoenzymatic approach that combines chemical and bio-catalyst has proven very useful in synthetic chemistry, however, mutual deactivation of chemical and bio-catalyst when employed in the same pot is still a challenge. In this context, the development of nanobiohybrid catalysts has played an important role and overcoming the issue of mutual deactivation between catalysts to a certain extent. Herein, we design and synthesize a novel heterogeneous recyclable nanobiohybrid catalyst comprising palladium nanoparticles and alpha-amylase from Aspergillus oryzae immobilized onto halloysite nanotubes as a solid heterogeneous support. Further, the wider applicability of the developed nanobiohybrid catalyst is revealed in the one-pot chemoenzymatic synthesis of functionalized biphenyls and bis(indolyl)methanes which consists of Pd-catalyzed Suzuki-Miyaura coupling and alpha-amylase mediated aza-Michael addition or electrophilic substitution reactions respectively. Further, the robustness and generality of the developed one-pot chemoenzymatic synthesis are demonstrated by incorporating different substitutions at the starting materials and obtaining the corresponding products in moderate to good yields.