A simple base-mediated synthesis of diverse substituted ring-fluorinated 4H-pyrans (monofluorinated 4H-pyrans) from trifluoromethylated alkenes and 1,3-dicarbonyl compounds was developed.
α-trifluoromethyl α,β-unsaturated esters as dipolarophiles pose considerable challenge due to expeditious defluorination and intrinsic steric hindrance. The present work provides an efficient access to valuable pyrrolidines bearing a trifluoromethylated all-carbon quaternary stereocenter through copper/M7-catalyzed asymmetric dipolar cycloaddition of α-trifluoromethyl α,β-unsaturated esters with azomethine
A one-pot synthesis of (E)-α-bromo-α,β-unsaturated esters and their trifluoromethylation: a general and stereoselective route to (E)-α-trifluoromethyl-α,β-unsaturated esters
作者:Feng-Ling Qing、Xingang Zhang
DOI:10.1016/s0040-4039(01)01153-4
日期:2001.8
Bromination of a phosphonate anion derived in situ from ethyl bis (2,2 2 -trifluoroethyl)phosphonoacetate 3 followed by the addition of aldehydes produced (E)-alpha -bromo-alpha,beta -unsaturated esters 5 stereo selectively. The treatment of 5 with FSO2CF2CO2Me and CuI in DMF/HMPA provided (E)-alpha -trifluoromethyl-alpha,beta -unsaturated esters 6. (C) 2001 Elsevier Science Ltd. All rights reserved.