1581710-02-2Relevant articles and documents
Optically active 2-acylheteroaromatic chromane compound used in the preparation of the catalyst precursor, (by machine translation)
-
Paragraph 0036-0038, (2018/02/28)
PROBLEM TO BE SOLVED: To obtain an optically active 2-acyl chroman compound in a high yield.SOLUTION: The optically active 2-acyl chroman compound is obtained in a high yield with a high enantiomeric excess by the reaction of a keto phenol compound with hydroperoxide in the presence of an N-spiro C-asymmetric chiral quaternary ammonium iodide as a catalyst precursor.
High-turnover hypoiodite catalysis for asymmetric synthesis of tocopherols
Uyanik, Muhammet,Hayashi, Hiroki,Ishihara, Kazuaki
, p. 291 - 294 (2014/08/05)
The diverse biological activities of tocopherols and their analogs have inspired considerable interest in the development of routes for their efficient asymmetric synthesis. Here, we report that chiral ammonium hypoiodite salts catalyze highly chemo- and enantioselective oxidative cyclization of γ-(2-hydroxyphenyl)ketones to 2-acyl chromans bearing a quaternary stereocenter, which serve as productive synthetic intermediates for tocopherols. Raman spectroscopic analysis of a solution of tetrabutylammonium iodide and tert-butyl hydroperoxide revealed the in situ generation of the hypoiodite salt as an unstable catalytic active species and triiodide salt as a stable inert species. A high-performance catalytic oxidation system (turnover number of ~200) has been achieved through reversible equilibration between hypoiodite and triiodide in the presence of potassium carbonate base.We anticipate that these findings will open further prospects for the development of high-turnover redox organocatalysis.
