Affiliation:
1. Faculty of Pharmacy Keio University 1-5-30 Shibakoen Minato-ku Tokyo 105-8512 Japan
2. Laboratory for Chemistry and Life Science Institute of Innovative Research Tokyo Institute of Technology 4259 Nagatsuta, Midori-ku Yokohama 226-8503 Japan
3. Department of Chemistry Graduate School of Science Kitasato University 1-15-1 Kitasato Minami-ku Sagamihara Kanagawa 252-0373 Japan
Abstract
Abstract1,1’,10,10’‐Biphenothiazine and its S,S,S’,S’‐tetroxide are diaza[5]helicenes with N−N linkages. Kinetic experiments on racemization together with DFT calculations revealed that they undergo inversion through the N−N bond breaking pathway rather than the general conformational pathway. In these diaza[5]helicenes with this inversion mechanism, the reduction of electronic repulsion in the N−N bond by modification of S to SO2 at the outer position of the helix led to a significantly higher inversion barrier, 35.3 kcal/mol, compared to [5]helicene. 1,1’,10,10’‐Biphenothiazine S,S,S’,S’‐tetroxide was highly resistant to acid‐mediated N−N bond breaking and racemization under acidic conditions.
Funder
Japan Society for the Promotion of Science
Naohiko Fukuoka Memorial Foundation
Sumitomo Foundation
Subject
General Chemistry,Catalysis,Organic Chemistry