Photochemical and Thermal Isomerization Processed of A chiral Auxiliary Based Donor-Acceptor Substituted chiroptical Molecular Switch;Convergent synthesis Improved Resolution and Switching properties

摘要

A new type of chiroptical molecular swithc is presented thwre irradiation empolying different wave-lengths of ligh induces a reversible helix inversion of s sterically overcrowded alkene bearing a second chiral entity in the form of a stereogenic center present in a pyrroliding unit.The additional stereogenic center in the chiral auxiliary group has a sistince in fluence 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 differeces between the various states of hte switch system resulting in a small but signifi-cant directional preference in the helix inversion steps.