187-83-7Relevant articles and documents
Helicene synthesis by Br?nsted acid-catalyzed cycloaromatization in HFIP [(CF3)2CHOH]
Fujita, Takeshi,Shoji, Noriaki,Yoshikawa, Nao,Ichikawa, Junji
, p. 396 - 403 (2021/03/20)
A facile synthesis of carbo- and heterohelicenes was achieved via tandem cycloaromatization of bisacetal precursors, which were readily prepared through C-C bond formation by Suzuki-Miyaura coupling. This cyclization was efficiently realized by a catalytic amount of trifluoromethanesulfonic acid (TfOH) in a cation-stabilizing solvent, 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP), which readily allowed gram-scale syntheses of higher-order helicenes, double helical helicenes, and heterohelicenes.
Enantioseparation on Riboflavin Derivatives Chemically Bonded to Silica Gel as Chiral Stationary Phases for HPLC
Kumano, Daisuke,Iwahana, Soichiro,Iida, Hiroki,Shen, Chengshuo,Crassous, Jeanne,Yashima, Eiji
, p. 507 - 517 (2015/08/03)
Acetylated and/or 3,5-dimethylphenylcarbamated riboflavins were prepared and the resulting riboflavin derivatives as well as natural riboflavin were regioselectively immobilized on silica gel through chemical bonding at the 5'-O- or 3-N-position of the riboflavin to develop novel chiral stationary phases (CSPs) for enantioseparation by high-performance liquid chromatography (HPLC). The chiral recognition abilities of the obtained CSPs were significantly dependent on the structures of the riboflavin derivatives, the position of the chemical bonding on the silica gel, and the structures of the racemic compounds. The CSPs bonded at the 5'-O-position on the silica gel tended to well separate helicene derivatives, while the CSPs bonded at the 3-N-position composed of acetylated and 3,5-dimethylphenylcarbamated riboflavins showed a better resolving ability toward helicene derivatives and bulky aromatic racemic alcohols, respectively, and some of them were completely separated into the enantiomers. The observed difference in the chiral recognition abilities of these riboflavin-based CSPs is discussed based on the difference in their structures, including the substituents of riboflavin and the positions immobilized on the silica gel. Chirality 27:507-517, 2015.
Synthesis of derivatives of phenanthrene and helicene by improved procedures of photocyclization of stilbenes
Talele, Harish R.,Gohil, Monik J.,Bedekar, Ashutosh V.
scheme or table, p. 1182 - 1186 (2009/12/25)
An improved method has been developed for photocyclization of stilbene to construct phenanthrenes and benzo[c]phenanthrenes. This reaction is promoted by iodine while tetrahydrofuran is used as an efficient and inexpensive scavenger of hydroiodic acid produced during the photocyclization sequence. In another process, cyclohexene is used as a reagent for dehydrogenation step in place of THFI2.
