Efficient and Selective N-Methylation of Nitroarenes under Mild Reaction Conditions

Herein, we report a straightforward protocol for the preparation of N,N-dimethylated amines from readily available nitro starting materials using formic acid as a renewable C₁ source and silanes as reducing agents. This tandem process is efficiently accomplished in the presence of a cubane-type Mo₃ PtS₄ catalyst. For the preparation of the novel [Mo₃ Pt(PPh₃ )S₄ Cl₃ (dmen)₃ ]⁺ (3⁺ ) (dmen: N,N'-dimethylethylenediamine) compound we have followed a [3+1] building block strategy starting from the trinuclear [Mo₃ S₄ Cl₃ (dmen)₃ ]⁺ (1⁺ ) and Pt(PPh₃ )₄ (2) complexes. The heterobimetallic 3⁺ cation preserves the main structural features of its 1⁺ cluster precursor. Interestingly, this catalytic protocol operates at room temperature with high chemoselectivity when the 3⁺ catalyst co-exists with its trinuclear 1⁺ precursor. N-heterocyclic arenes, double bonds, ketones, cyanides and ester functional groups are well retained after N-methylation of the corresponding functionalized nitroarenes. In addition, benzylic-type as well as aliphatic nitro compounds can also be methylated following this protocol.