- Stereochemical significance of O to N atom interchanges within cationic helicenes: experimental and computational evidence of near racemization to remarkable enantiospecificity
Labrador, G. M.; Besnard, C.; Bürgi, T.; Poblador-Bahamonde, A. I.; Bosson, J.; Lacour, J.
Chem. Sci. 2019, 10, 7059-7067
Oxygen atoms of cationic dioxa and azaoxa helicenes can be exchanged by amino groups to form azaoxa and diaza helicenes respectively. The mild reaction conditions developed herein allow the construction of libraries of derivatives with sensitive and/or functionalized side chains. Using enantioenriched dioxa or azaoxa helicene precursors, these exchanges lead to either near racemization (es 3%) or to a remarkable enantiospecificity (es up to 97%). This unusual behavior is fully characterized via experimental and computational mechanistic evidences. Based on these investigations, the enantiospecificity of the first transformation can be improved to 57-61%.
open archive unige:121523