Ruthenium borrowing hydrogen

Madsen and co-workers have reported an important extension to the amine alkylation chemistry, in which oxidation takes place to give the amide product [13]. A ruthenium NHC complex is formed in situ by the reaction of [RuCl Ccod)] with a phosphine and an imidazolium salt in the presence of base. Rather than returning the borrowed hydrogen, the catalyst expels two equivalents of H. For example, alcohol 31 and benzylamine 27 undergo an oxidative coupling to give amide 32 in good isolated yield (Scheme 11.7). 

Hamid MHSA, Allen CL, Williams JMJ et al (2009) Ruthenium-catalyzed V-alkylation of amines and sulfonamides using borrowing hydrogen methodology. J Am Chem Soc 131(5) 1766-1774... 

Enyong AB, Moasser B (2014) Ruthenium-catalyzed Al-alkylation of amines with alcohols under mild conditions using the borrowing hydrogen methodology. J Org Chem 79(16) 7553-7563... 

Jumde VR, Gonsalvi L, Taddei M et al (2015) A ruthenium-based catalytic system for a mild borrowing-hydrogen process Eur J Org Chem 2015(8) 1829-1833... 

Yamaguchi K, He J, Mizuno N et al (2010) The borrowing hydrogen strategy by supported ruthenium hydroxide catalysts synthetic scope of syirunetrically and unsymmetrically substituted aitunes. Chem-Eur J 16(24) 7199-7207... 

Keywords Ruthenium Transfer Hydrogenation Enantioselective Borrowing Hydrogen C-C Bond Formation... 

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