Iridium-Catalyzed Asymmetric Hydrogenation of Tetrasubstituted α-Fluoro-β-enamino Esters: Efficient Access to Chiral α-Fluoro-β-amino Esters with Two Adjacent Tertiary Stereocenters
An iridium-catalyzed highly efficient asymmetric hydrogenation of challenging tetrasubstituted α-fluoro-β-enamino esters was successfully developed using bisphosphine–thiourea (ZhaoPhos) as the ligand, which prepared a series of chiral α-fluoro-β-amino esters containing two adjacent tertiary stereocenters with high yields and excellent diastereoselectivities/enantioselectivities (73%–99% yields, >25:1
FACILE SYNTHESIS OF α-FLUORO-β-KETOESTERS FROM POLYFLUOROALKENES
作者:Nobuo Ishikawa、Akio Takaoka、Hiroshi Iwakiri、Satoshi Kubota、S. R. F. Kagaruki
DOI:10.1246/cl.1980.1107
日期:1980.9.5
2-chloro-1,2,2-trifluoroethyl ketones and aryl 1,2,2,2-tetrafluoroethyl ketones were respectively prepared by the Friedel–Crafts acylation of trifluoroethene and by the Grignard arylation of N,N-diethyl-1,2,2,2-tetrafluoropropionamide, a hydrolyzed product of hexafluoropropene–diethylamine adduct. These alkyl and aryl polyfluoroalkyl ketones were subjected to base-induced dehydrohalogenation, and resulting
By utilising a chiral bicyclic guanidine as catalyst and triethylamine as additive, the first asymmetric Michael addition of α-fluoro-β-ketoesters to various cyclicenones has been successfully developed, affording a variety of Michael adducts with potential synthetic utilities with satisfactory stereoselectivity (up to 94 % ee and 4.3 : 1 dr).