Chemoselective N-tert-butoxycarbonylation and N-formylation of Amines by B(OSO3H)3/SiO2 as an Efficient Heterogeneous and Recyclable Catalyst

A simple, efficient, and cost-effective procedure for N-tert-butoxycarbonylation and N-formylation of amines (primary, secondary), respectively, with di-tert-butyl dicarbonate and 85% aqueous formic acid under solvent-free condition using B(OSO3H)3/SiO2 (SBSA) as a heterogeneous and recyclable catalyst has been developed. We demonstrated that the resulting catalyst is applicable to various aromatic and aliphatic amines giving excellent yields of the desired products in short reaction time (<20 min) at room temperature. The recoverability of the catalyst was achieved by a simple decantation and reused at least five times without significant degradation in catalytic activity. Furthermore, the leaching test showed no detectable homogeneous catalysis from active spices in the solution. SBSA act as a dual Brønsted/Lewis acid that is an air-stable and cost-effective solid acid. This protocol has shown excellent chemoselectivity.