Iodine Molecules within Triethylenediamine-Based Metal–Organic Frameworks for Hydrolysis/Alkylation Tandem Reactions

The integration of radionuclide iodine molecules in metal–organic frameworks (MOFs) for organic synthesis is attracting considerable research attention due to their specific catalytic performance. However, understanding the comprehensive catalytic behaviors of different types of molecular iodine encapsulated in MOFs for a sequential organic transformation is a great challenge. To address this issue, we have designed two triethylenediamine-functionalized MOFs assembled from 1,3,5-tricarboxyphenyl-2-(triethylenediaminemethyl)benzene-linker and {Cd(COO) 3 N} or {Cu 4 ( u 3 -OH) 2 (COO) 6 N} clusters. Both MOFs show good stability and adsorption of I 2 in the solution and vapor phases. Catalysts obtained after treatment with ethyl acetate present efficient catalytic activity in hydrolysis/alkylation tandem reactions in water. The mechanistic investigations disclose a sequential catalytic process comprising a “hidden” Brønsted acid catalytic hydrolysis of acetals to aldehydes followed by the I 2 -bonding Lewis acid catalytic alkylation of aldehydes to 3,3′-disubstituted 1 H -indoles.