Cu(i) coordination polymers (CPs) as tandem catalysts for three-component sequential click/alkynylation cycloaddition reaction with regiocontrol

Abstract

To expand coordination polymers (CPs) as solid catalysts to selectively catalyze the three-component tandem click/alkynylation reaction for their fully substituted triazole skeletons, two Cu(I)-based CPs (Cu^I-CPs), [CuBr(aas-TPB)]_n (1) and [Cu₃I₃(aas-TPB)₂]_n (2) (TPB = N,N,N-tri(3-pyridinyl)-1,3,5-benzenetricarboxamine), have been prepared. Because of the template effect of anions (Br⁻ and I⁻), the structure of compounds is regulated under solvothermal conditions. CP 1 exhibited a one-dimensional (1D) chain, while the double strand framework with the Cu₃I₃ cluster platform was observed in 2. Furthermore, the different product selectivities of catalyzing terminal alkynes, benzyl azide and bromoalkyne to synthesize triazole skeletons have been caused by the significantly structural diversity of 1 and 2. The distinct structural feature of 2 endows it with unique multinuclear platforms (Cu₃I₃) and reaction pathways to promote the three-component tandem click/alkynylation cycloaddition reaction. As a result, 2 can be an outstanding catalyst candidate for sequential click/alkynylation cycloaddition, while 1 can efficiently catalyze the generation of click products.