A family of modularly desig
ned phosphi
ne-phosphites (P-OP), possessi
ng a C-C-O backbo
ne, hasbee
n sy
nthesized a
nd evaluated i
n the iridium-catalyzed asymmetric hydroge
natio
n of N-aryl imi
nes.The e
na
ntioselectivity of this reactio
n is highly depe
nde
nt o
n the
nature of the liga
nd, a
nd catalystsbridged by a
n oxyethyle
ne
fragme
nt have produced sig
nifica
ntly higher e
na
ntiomeric excesses (
ee >20%) tha
n their
o-oxyphe
nyle
ne cou
nterparts. Structural studies by X-ray crystallography a
nd NMRspectroscopy of complexes with the formulatio
n [Ir(COD)(P-OP)]BF
4 a
nd Ir(Cl)(CO)(P-OP), compleme
nted by DFT calculatio
ns of model compou
nds of the chlorocarbo
nyls, have show
n importa
nt differe
ncesbetwee
n complexes bridged by a
n aliphatic or a
n aromatic bridge, regardi
ng the iridacycle co
nformatio
na
nd the locatio
n of phosphi
ne substitue
nts. Catalyst optimizatio
n has afforded e
na
ntioselectivities
from72 to 85% ee i
n the hydroge
natio
n of several N-aryl imi
nes.