Synthesis of 4-trifluoromethylazetidin-2-ones by a novel 2+2 photocycloaddition of 3-trifluoromethyl-quinoxalin-2-one or -1,4-benzoxazin-2-one to ketene.
In this study, we have developed solvent‐controlled regioselective Mannich reaction of cyclicimines (benzoxazinones) with various ketones by using ʟ‐proline as catalyst to afford Mannich products in high yields with excellent enantio‐ and diastereoselectivity. The unsymmetrical ketones produced the linear isomer as the major product in chloroform solvent. On contrary, using the DMSO solvent favoured
herein is a direct C−H trifluoromethylation of quinoxalin‐2(1H)‐ones with sodium trifluoromethanesulfinate. This protocol affords a series of 3‐trifluoromethylquinoxalin‐2(1H)‐one derivatives in moderate to excellent yields under transition‐metal‐freeconditions. The present methodology features utilization of the inexpensive trifluoromethyl source without transition‐metal‐catalysts, mild reaction conditions
Organocatalytic Asymmetric Synthesis of Dihydrobenzoxazinones Bearing Trifluoromethylated Quaternary Stereocenters
作者:Hengqiao Lou、Yongtao Wang、Enze Jin、Xufeng Lin
DOI:10.1021/acs.joc.5b02848
日期:2016.3.4
enantioselective aza-Friedel–Crafts reaction of trifluoromethyl benzoxazinones with pyrroles is reported. Under mild conditions, a range of enantioenriched dihydrobenzoxazinones bearing trifluoromethylated quaternary stereocenters could be obtained in good to excellent yield and ee. A remarkable fluorine effect is observed, and preliminary mechanistic studies combined with theory calculations suggest that tr