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Aerobic Oxidation of Primary Amines to Imines in Water using a Cobalt Complex as Recyclable Catalyst under Mild Conditions
Author(s) -
Hazra Susanta,
Pilania Priti,
Deb Mayukh,
Kushawaha Ajay Kishor,
Elias Anil J.
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201803251
Subject(s) - catalysis , chemoselectivity , benzylamine , cobalt , chemistry , primary (astronomy) , imine , yield (engineering) , catalytic cycle , ammonia , oxidative coupling of methane , organic chemistry , combinatorial chemistry , materials science , physics , astronomy , metallurgy
Oxidative coupling of primary amines to imines has been achieved by using a water soluble cobalt complex as catalyst and air as the oxidant at near ambient conditions. Aromatic, heteroaromatic and aliphatic amines were successfully converted to the corresponding imines with yields of up to 96 %. A 20 gram scale reaction for the synthesis of imine from benzylamine in good yield is also demonstrated with this method. The catalyst has been found to be reusable with up to five cycles. It is highly efficient, gives a turnover number (TON) of up to 128, and shows chemoselectivity with the only byproducts being water and ammonia. Control experiments and mechanistic studies indicate that the Co II /Co III catalytic cycle is responsible for these oxidative transformations. Some of the reactive intermediates of this reaction have also been isolated and structurally characterized.