Enantioselective synthesis of planar-chiral 1,11-dioxa[11]paracyclophane-derived phosphoramidites and their use as chiral ligands
摘要:
A library of bench-stable planar-chiral 1,11-dioxa[11]paracyclophane-derived phosphoramidites was synthesized by a three step procedure: enantioselective ortho-lithiation, reductive amination and coupling with phosphorochloridites. The efficacy of these phosphoramidite as chiral ligands was tested in the Pd-catalyzed allylic alkylation of dimethyl malonate and the Cu-catalyzed ethylation of chalcone under the reported conditions, with moderate enantioselectivity being obtained. (C) 2016 Elsevier Ltd. All rights reserved.
Enantioselective Synthesis of Planar-Chiral 1,n-Dioxa[n]paracyclophanes via Catalytic Asymmetric ortho-Lithiation
摘要:
Highly enantioselective ortho-lithiation and dilithiation of 1,n-dioxa[n]paracyclophanes were realized with the use of see-butyllithium and a catalytic or stoichiometric amount of sparteine. Quenching with various electrophiles, such as iodine, iodomethane, and chlorodiphenylphosphine, afforded chiral mono- and disubstituted paracyclophanes with good to excellent ee.