Novel phosphinobioxazines as chiral ligands in palladium-catalyzed enantioselective allylic substitution
摘要:
Novel C-2-symmetric chiral (4S,4'S)-bisphosphinobioxazine 2a, a six-membered analog of (4S,4S')bisphosphinobioxazoline (Phos-Biox, 1), and monophosphinobioxazine 2b have been synthesized and used as chiral ligands for Pd-catalyzed asymmetric allylic substitutions of rac-1,3-diphenyl-2-propenyl acetate with dimethyl malonate. C-2-Symmetric bisphosphinobioxazine 2a exhibited moderate enantioselectivities (63-84% ee) whereas excellent enantioselectivities (94-95% ee) were observed with monophosphinobioxazine 2b. (C) 1999 Elsevier Science Ltd. All rights reserved.
Chiral 6-phenyl-2,3-bismethylenemethoxycarbonyl-[1,4]-dioxane as a designer synthon for an efficient and short synthesis of optically pure 2,6-dioxabicyclo[3.3.0]octane-3,7-dione
作者:Ganesh Pandey、Amrut L. Gaikwad、Smita R. Gadre
DOI:10.1016/j.tetlet.2005.11.116
日期:2006.1
Chiral 6-phenyl-2,3-bismethylenemethoxycarbonyl-[1,4]-dioxane, synthesized by the PET cyclization of 8, has been used as a designer synthon for an efficient and shortsynthesis of optically pure 2,6-dioxabicyclo[3.3.0]octane-3,7-dione.