%0 Generic
%A Englert, Ulli
%A Hu, Chunhua
%A Salzer, Albrecht
%A Alberico, Elisabetta
%D 2004
%T Conformationally Constrained Diphosphines Derived
from (η6-(S)-1-(dimethylamino)indane)Cr(CO)3: Synthesis
and Application in Enantioselective Hydrogenation
%U https://acs.figshare.com/articles/dataset/Conformationally_Constrained_Diphosphines_Derived_from_sup_6_sup_i_S_i_1_dimethylamino_indane_Cr_CO_sub_3_sub_Synthesis_and_Application_in_Enantioselective_Hydrogenation/3317179
%R 10.1021/om049628z.s002
%2 https://ndownloader.figshare.com/files/5155912
%K dimethylamino
%K PR 2 group
%K Conformationally Constrained Diphosphines Derived
%K donor group combination
%K enantiopure diphosphine ligands
%K dimethyl itaconate
%K PPh 2 group
%X Three new enantiopure diphosphine ligands have been prepared starting from [(η6-(1-dimethylamino)indane)Cr(CO)3] by means of a stereoselective synthetic strategy involving
highly diastereoselective complexation of the Cr(CO)3 moiety to (S)-(1-dimethylamino)indane,
regioselective substitution in the 7-position with the PPh2 group, and, after exchange of the
amino group for a chloro substituent with chloroformic esters, introduction of a PR2 group
(R = Ph, t-Bu, Cy) in the benzylic position. The stereochemical course of the synthesis has
been confirmed by the X-ray determination of the molecular structure of one intermediate
and of one of the three ligands. The ligands have been tested in the rhodium-promoted
enantioselective hydrogenation of methyl (Z)-N-acetamidocinnamate and dimethyl itaconate.
Enantiomeric excesses ranging from 9 to 88% ee have been obtained, depending on the nature
of the R substituent on the ligand, with the donor group combination o-PPh2/α-PCy2 (S,Rp)-6c outperforming the other two. The new ligands, which bear the coordinating teeth on the
stiff backbone provided by the indane framework, compare well with the parent conformationally unlocked “Daniphos” ligands: in the hydrogenation of dimethyl itaconate the new
ligand (S,Rp)-6c provides better results as to conversion and enantioselectivity compared
to the analogous acyclic ligand.
%I ACS Publications