Indium-Organic Framework with Topology as a Versatile Catalyst for Highly Efficient One-Pot Strecker Synthesis of α-aminonitriles.

An In(III) based metal-organic framework (MOF), In-pbpta, with topology was constructed from the trigonal prismatic [In(μ-O)(HO)(OC-)] secondary building unit (SBU) and a custom-designed tetratopic linker Hpbpta (pbpta = 4,4',4″,4‴-(1,4-phenylenbis(pyridine-4,2,6-triyl))-tetrabenzoic acid)). The obtained MOF shows a Brunauer-Emmett-Teller surface area of 1341 m/g with a pore volume of 0.64 cm/g, which is the highest among the scarcely reported In--MOFs. The constructed MOF demonstrates excellent performance as a heterogeneous Lewis acid catalyst for highly efficient conversion in a one-pot multicomponent Strecker reaction for the preparation of α-aminonitriles under solvent-free conditions, which can be easy to separate and recycle without significant loss of activity for up to seven cycles. The computational modeling studies suggest the presence of the three substrates in close vicinity to the In-oxo cluster. The strong interactions of the aldehyde/ketone and the amine with the In-oxo cluster together with the readily available cyanide ion around the In-oxo cluster lead to high catalytic conversion within a short period of time for the MOF catalyst. Our work therefore lays a foundation to develop MOF as a new class of efficient heterogeneous catalyst for one-pot Strecker reaction.