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  1. Stereochemical significance of O to N atom interchanges within cationic helicenes: experimental and computational evidence of near racemization to remarkable enantiospecificity
    Geraldine M. Labrador, Céline Besnard, Thomas Bürgi, Amalia I. Poblador-Bahamonde, Johann Bosson, Jérôme Lacour
    Chem. Sci. 2019, 10, 7059-7067

Oxygen atoms of cationic dioxa and azaoxa [6]helicenes can be exchanged by amino groups to form azaoxa and diaza [6]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%.

Dataset: 10.26037/yareta:ikmm2hq375e75ebqq35mem5dsa

DOI: 10.1039/C9SC02127B 

open archive unige:121523