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Silver‐Catalysed Enantioselective Addition of OH and NH Bonds to Allenes: A New Model for Stereoselectivity Based on Noncovalent Interactions
Author(s) -
Arbour Jannine L.,
Rzepa Henry S.,
ContrerasGarcía Julia,
Adrio Luis A.,
Barreiro Elena M.,
Hii King Kuok Mimi
Publication year - 2012
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.201200547
Subject(s) - stereoselectivity , enantioselective synthesis , chemistry , intramolecular force , non covalent interactions , chirality (physics) , tetrahydrofuran , enantiomer , stereochemistry , computational chemistry , catalysis , molecule , organic chemistry , hydrogen bond , physics , quantum mechanics , solvent , quark , nambu–jona lasinio model , chiral symmetry breaking
The ability of silver complexes to catalyse the enantioselective addition of OH and NH bonds to allenes is demonstrated for the first time by using optically active anionic ligands that were derived from oxophosphorus(V) acids as the sources of chirality. The intramolecular addition of acids, alcohols, and amines to allenes can be achieved with up to 73 % ee . The exploitation of a CH anomeric effect allowed the absolute configuration of a sample of 2‐substituted tetrahydrofuran of low ee to be unambiguously assigned by comparison of the chiroptical ORD and VCD measurements with calculated spectra. In the second part of the work, the origin of the stereoselectivity was probed by DFT free‐energy calculations of the transition states. A new model of enantiomeric differentiation was developed that was based on noncovalent interactions. This model allowed us to identify the source of stereoselectivity as weak attractive interactions; such dispersive forces are often overlooked in asymmetric catalysis. A new computational approach was developed that represents these interactions as colour‐coded isosurfaces that are characterised by the reduced density‐gradient profile.