A Supramolecular Chiral Auxiliary Approach: "Remote Control" of Stereochemistry at a Hierarchically Assembled Dimeric Helicate

David Van Craen; Markus Albrecht; Gerhard Raabe; Fangfang Pan; Kari Rissanen

doi:10.1002/chem.201600158

A Supramolecular Chiral Auxiliary Approach: "Remote Control" of Stereochemistry at a Hierarchically Assembled Dimeric Helicate

Chemistry. 2016 Mar 1;22(10):3255-3258. doi: 10.1002/chem.201600158. Epub 2016 Feb 2.

Authors

David Van Craen¹, Markus Albrecht², Gerhard Raabe¹, Fangfang Pan³, Kari Rissanen³

Affiliations

¹ Institut für Organische Chemie, RWTH Aachen, Landoltweg 1, 52074, Aachen, Germany.
² Institut für Organische Chemie, RWTH Aachen, Landoltweg 1, 52074, Aachen, Germany. Markus.Albrecht@oc.rwth-aachen.de.
³ Department of Chemistry, University of Jyväskylä, P.O. Box 35, 40014 University, Jyväskylä, Finland.

PMID: 26833393
DOI: 10.1002/chem.201600158

Abstract

Dimeric hierarchically-assembled titanium(IV) helicates are in solvent-dependent equilibrium with the corresponding monomers. Statistically formed mixtures of such complexes bearing chiral stereocontrolling ligands and achiral diene-substituted ligands show high diastereoselectivity and reasonable enantioselectivity in the Diels-Alder reaction with maleimides if the reaction proceeds with the dimer but not with the monomer. Thus, solvent dependent switching between the monomer and dimer enables on/off switching of the enantioselectivity.

Keywords: Diels-Alder reaction; helicates; lithium; self-assembly; titanium.