In water alkylation of amines with alcohols through a borrowing hydrogen process catalysed by ruthenium nanoparticles

A simple and environmentally benign procedure for the synthesis of secondary amines in water has been developed. Combining Ru3(CO)12, tetraphenylcyclopentadienone and a small quantity of TGPS-750-M surfactant, primary and secondary alcohols were alkylated at N employing equimolar amounts of aromatic amines in water. The reaction occurs under microwave (MW) dielectric heating with high conversion and high yield. When required, the use of biomass-derived 2-MeTHF or GVL as a co-solvent is possible. Under the influence of MWs, a Ru nanoparticle-nanomicelle combination was formed acting as an effective and recyclable catalyst. This protocol was also employed for "in water" cyclisation to synthesise biologically relevant pyrrolobenzodiazepines (PBDs).