Practical Photocatalytic Trifluoromethylation and Hydrotrifluoromethylation of Styrenes in Batch and Flow
作者:Natan J. W. Straathof、Sten E. Cramer、Volker Hessel、Timothy Noël
DOI:10.1002/anie.201608297
日期:2016.12.12
represent a challenging class of substrates for current radical trifluoromethylation and hydrotrifluoromethylation methods due to a myriad of potential side reactions. Herein, we describe the development of mild, selective and broadly applicable photocatalytic trifluoromethylation and hydrotrifluoromethylation protocols for these challenging substrates. The methods use fac‐Ir(ppy)3, visible light and
enantiomeric excess (71%–83% ee). Ru-BINAP-catalyzed hydrogenation converted 2-trifluoromethyl-acrylic acid to the corresponding saturated acid, the ester-ification and reduction of which gave opticallyactive2-(trifluoromethyl)propan-1-ol in 80% ee.
The hydrogenation of (E)-2-(trifluoromethyl)alk-2-en-1-ols catalyzed by Ru-2, 2'-bis(diphynylphosphino)-1, 1'-binaphthyl (Ru-BINAP) and Rh-BINAP was carried out with good enantiomeric excess (71-83% ee). Ru-BINAP-catalyzed hydrogenation converted 2-(trifluoromethyl)acrylic acid to the corresponding saturated acid whose esterification and reduction provided optically active 2-(trifluoromethyl)propan-1-ol in 80% ee.