1404310-27-5Relevant articles and documents
Hydrogen-bonding thiourea organocatalysts: The privileged 3,5-bis(trifluoromethyl)phenyl group
Lippert, Katharina M.,Hof, Kira,Gerbig, Dennis,Ley, David,Hausmann, Heike,Guenther, Sabine,Schreiner, Peter R.
supporting information, p. 5919 - 5927 (2013/01/15)
We present evidence that the privileged use of the 3,5-bis(trifluoromethyl) phenyl group in thiourea organocatalysis is due to the involvement of the ortho-CH bond in the binding event with Lewis-basic sites. We utilized a combination of low-temperature IR spectroscopy, 2D NMR spectroscopy, nano-MS (ESI) investigations, as well as density functional theory computations [M06/6-31+G(d,p), including solvent corrections as well as natural bond orbital and atoms-in-molecules analyses] to support our conclusions that bear implications for catalyst design. The present work reveals that thiourea derivatives bearing a 3,5-bis(trifluoromethyl)phenyl group interact with Lewis basic sites of carbonyl derivatives through NH and highly polarized ortho-CH interactions in hydrogen-bonded complexes. Evidence is provided through a combination of DFT, variable-temperature IR and NMR spectroscopy, as well as MS (ESI) studies.