Preparation and use of DMF-stabilized iridium nanoclusters as methylation catalysts using methanol as the C1 source

Abstract

We report methylations of alcohols and anilines catalyzed by DMF-stabilized Ir nanoclusters using methanol as the C1 source. The DMF-stabilized Ir nanoclusters were prepared in one step and have diameters of 1-1.5 nm. They react in a borrowing-hydrogen reaction and are efficient methylation catalysts (TON up to 310 000).

Iridium Clusters Encapsulated in Carbon Nanospheres as Nanocatalysts for Methylation of (Bio)Alcohols

“…To date, however, the reported C−H methylation reactions using methanol as methylating reagent and with substrate scope pertaining to ketones, allenes, amines, and indoles are mainly catalyzed by homogeneous transition metal catalysts (e.g., Ru, Rh, and Ir). Efficient C−H methylation of readily available (bio)alcohols for the synthesis of methyl functionalized higher alcohols is limited . Moreover, to achieve this purpose, the development of highly active, selective, and recyclable heterogeneous catalysts is needed from the sustainable and green chemistry viewpoints.…”

Solution Synthesis ofN,N‐Dimethylformamide‐Stabilized Iron‐Oxide Nanoparticles as an Efficient and Recyclable Catalyst for Alkene Hydrosilylation

“…Pd nanoclusters (NCs) with a particle size of 1–2 nm have been demonstrated to be a practical and recyclable catalyst for Suzuki–Miyaura, Mizoroki–Heck, and Migita–Kosugi–Stille reactions ,. Cu NPs can be used for Sonogashira coupling and O‐arylation,, and Ir NCs catalyze the β‐methylation of alcohols through hydrogen autotransfer . Furthermore, there are recent reports with iron‐oxide nanocatalysts in various organic reactions…”

“…The catalyst retained its nanosized particle size, and the photoluminescence characteristics before, after, and in the recycling reactions were similar (Scheme , Figures and S9–S12). Therefore, the DMF‐stabilized Fe 2 O 3 nanoparticles remain during the catalytic reaction, generating partially open sites by liberation of a portion of the DMF molecules that could act as active catalysts in the reaction, as proposed in previously reported DMF‐stabilized Ir and Cu nanoparticles ,. Even after the fifth run, the particle size did not change much (Figure S11).…”

Recent Advances in Methylation: A Guide for Selecting Methylation Reagents

“…In 2017, Obora et al. used self‐prepared DMF‐stabilized Ir nanoclusters (Ir NCs) as a catalyst in the hydrogen‐borrowing reaction for mono N‐methylation of anilines (Table ) …”

“…In 2017, Obora et al used self-prepared DMF-stabilized Ir nanoclusters (Ir NCs) as ac atalysti nt he hydrogen-borrowing reactionfor mono N-methylation of anilines (Table 33). [224] In 2017, Tu et al carriedo ut mono N-methylation of anilines by using self-preparedN -heterocyclic carbene iridium (NHC-Ir) polymer (347)a st he catalyst in excellent yields (Table 34). Undero ptimizedconditions, aryl sulfonamide can be monomethylated.…”