hydrosilylation of aldimines and ketimines in the presence of NaBArF 24 . A comprehensive study of the activity 26 proved that it performed efficiently for a very
broad range of acyclic imines, employing Et 3 SiH as reducing agent under mild
conditions. More recently, related Cp*Ir(III)Cl complexes featuring cyclometallated
phosphine ligands have been described, although modest yields were obtained even
in the presence of NaBArF 24 [63].
Further work on Ir-catalyzed hydroamination/hydrosilylation tandem reactions
has been reported by Messerle’s group using NHC-containing complexes 27, 28,
and 29 as catalysts and NaBArF 24 as additive (Fig. 11) [64]. The use of Ph 2 SiH 2 as
N
Ir
Cl
(OC) 3 Cr
25
NMe 2
N
H 3 C
R
R'
HN
H 3 C
R
R'
H
1) Et 3 SiH, 25 (2.5 mol %)
2) H 2 O
PhHN
PhHN
PhHN
NMe 2
PhHN
NHPh
PhHN
NHPh
NH
MeO
MeO
Products:
Scheme 7 Depiction of catalyst 25 and substrate scope for the hydrosilylation/hydrolysis of imines
catalyzed by 25
N
Ir
Cl
26
Fig. 10 Depiction of iridacycle 26
27
Ir
CO
CO
Cl
N
N
28
Ir
CO
CO
Cl
N
N
29
Ir
CO
CO
Cl
N
N
O
Ir
CO
OC
Cl
N
N
Fig. 11 Depiction of NHC-Ir catalysts 27–29
Iridium-Catalyzed Silylation
237