Macroreticular POLITAG-Pd(0) for the waste minimized hydrogenation/reductive amination of phenols using formic acid as hydrogen source

Abstract

The preparation of value-added chemicals from renewable bio-based sources is a key strategy to promote the development of a greener chemical production. Aiming at contributing towards this goal, we herein report the results obtained in the valorization of lignin-derived phenolic compounds via a cascade hydrogenation/reductive amination process affording to N-substituted cyclohexylamines. For this purpose we have developed a tailor-made macroreticular POLITAG-20-Pd(0) heterogeneous catalytic system that has allowed the minimization of the H-source employed and the use of water as safe reaction medium. The catalyst shows a trustworthy long durability being recycled for representative 20 consecutive runs. The high efficiency and selectivity of the protocol also allow us to minimize the waste associated to the work-up procedure avoiding additional acidification steps. Moreover, the protocol revealed to be suitable also in the cascade process when 1-naphthol is used as starting material opening the way to a new step-economical route for the synthesis of N-alkyl-1,2,3,4-tetrahydronaphthalen-1-amines as key intermediate for the preparation of API.