Two Zn(II)/Cd(II) Coordination Polymers as Recyclable
Heterogeneous Catalysts for an Efficient Room-Temperature Synthesis
of α‑Aminonitriles via the Solvent-Free Strecker Reaction
posted on 2022-12-22, 17:38authored bySheeba Khan, Datta Markad, Sanjay K. Mandal
The
α-aminonitriles are versatile building blocks in the
synthesis of natural or artificial amino acids as well as important
intermediates in organic synthesis. For their synthesis, the three-component
Strecker reaction involving an aldehyde or a ketone together with
amines and trimethylsilyl cyanide is used. In the literature, hydrothermally
produced metal-based heterogeneous Lewis acid catalysts have been
utilized in various solvents. In this work, we aimed at a greener
approach toward such catalysis by (a) making two precatalysts with
d10 metal centers, {[Zn(hipamifba)(H2O)]·2H2O}n (1) and {[Cd(hipamifba)(H2O)2]·2H2O}n (2) (where H2hipamifba = 4-(((4-((carboxymethyl)
carbamoyl)phenyl)amino)methyl)benzoic acid), via an easy and scalable
room-temperature method, and (b) showcasing the use of these coordination
polymers (CPs) as very efficient, recyclable, and heterogeneous catalysts
for the Strecker reaction to form α-aminonitriles in high yields
under solvent-free reaction at ambient conditions. This has also allowed
us to demonstrate the importance of open metal sites in such catalysis
through an efficiency comparison between activated 1 and 2. In addition, activated 2 exhibited a wide substrate scope
including a natural product Girgensohnine, providing
an example of a natural product synthesis by a CP catalyst via an
organic transformation such as the Strecker reaction.