title: Photochemical and thermal isomerization processes of a chiral auxiliary based donor-acceptor substituted chiroptical molecular switch: convergent synthesis, improved resolution and switching properties.
abstract: A new type of chiroptical molecular switch is presented where irradiation employing different wavelengths of light induces a reversible helix inversion of a sterically overcrowded alkene bearing a second chiral entity in the form of a stereogenic center present in a pyrrolidine unit. The additional stereogenic center in the chiral auxiliary group has a distinct influence on the switching selectivity of this system and greatly facilitates the resolution of the different diastereoisomers, which is a considerable improvement compared with previously reported systems. In addition, the pyrrolidine stereogenic center causes small energetic differences between the various states of the switch system resulting in a small but significant directional preference in the helix inversion steps.
authors.affiliation: Department of Organic and Molecular Inorganic Chemistry, Stratingh Institute, University of Groningen, The Netherlands.
authors.forename: Richard A
authors.initials: RA
authors.lastname: van Delden
authors.forename: Johannes H
authors.initials: JH
authors.lastname: Hurenkamp
authors.forename: Ben L
authors.initials: BL
authors.lastname: Feringa