Fast and selective iron-catalyzed transfer hydrogenations of aldehydes
摘要:
An efficient iron-based catalyst system consisting of Fe(BF)(4)center dot 6H(2)O and P(CH2CH2PPh2)(3) [tetraphos, (PP3)] is presented for the highly selective transfer hydrogenation of aromatic, aliphatic, and alpha,beta-unsaturated aldehydes. A wide range of substrates including aldehydes with other reducible functional groups gave the corresponding alcohols in good yields. Formic acid is applied as a cheap, environmentally benign and easy to handle hydrogen source. Notable features of the presented methodology are the fast reactions under mild conditions. Advantageously compared to most transfer hydrogenations, no stoichiometric amounts of base additives are required. (C) 2013 Elsevier B.V. All rights reserved.