A Cu–MOF-catalyzed C–H functionalization of substituted amidines was developed for the facile and efficient synthesis of benzimidazoles.

The catalytic [5 + 1] annulation/5-exo-cyclization reaction of amidines with diynes is reported herein. This protocol provides highly atom-economical access to fabricate two nitrogen-containing heterocycles in one step with high efficiency and selectivity. Significantly, this reaction represents the first example of using diyne as a one-carbon reaction partner in C-H functionalization. Kinetic isotope effects suggested that the catalytic cycle of this reaction is initiated by the cleavage of the ortho C-H bond in the N-phenyl ring of amidines, which is likely involved in the rate-limiting step. Calculations based on density functional theory (DFT) indicated that C-H activation and the formation of Rh(V) species via 5-exo-cyclization could be vital processes for this cascade transformation.

An efficient synthesis of 2,3‐fused pyridines through a HKUST‐1 (copper(II) 1,3,5‐benzenetricarboxylate) catalyzed sequential amination/annulation/aromatization reaction of carbonyl compounds and N‐propargylamine is presented herein. The reaction is not restricted to reactive ketones, wherein the five‐, six‐membered cyclic ketones and benzyl, aryl ketones show good reactivity with N‐propargylenamine, delivering pyridines in moderate to good yields. Under reaction conditions devoid of high temperature and expensive catalyst, this method exhibits broad tolerance of functional groups, including CN, alkyl, benzyl and methoxy moieties as well as unprotected phenolic hydroxy group. Additionally, the role of organic link for HKUST‐1 has been considered as a key parameter for this transformation.

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