Very recently Williams [242] described the TH of ketones catalysed by a family
of Cp*Ir derivatives using 2-propanol as the hydrogen donor (Scheme 83). Isotopiclabelling experiments, KIE measurements and NMR kinetic studies allow the
authors to propose the occurrence of a single kinetically relevant step in which a
[Ir]
Cl
H
O
O
[Ir] O
Cl
O
H
H
H
[Ir] H
Cl
H
[Ir] H
Cl
H
[Ir] H
Cl
H
O
O
H
H
O
O
1 / 2 [IrCl(COD)]2 +
PR 2
PR 2
- COD
PR 2
Ir
PR 2
[Ir] =
Scheme 82 Catalytic cycle for the TH of alkenes using 1,4-dioxane as the hydrogen donor with an
in situ generated iridium(I) catalyst [194]
Ir
N
X
N
Ar
X = H, Cl; Ar = SO 2 (4-C 6 H 4 Y); Y = Me, F
Ir
N
N
S
O
O
Y
Ir
N
H
N
Ar
Ir
N N
Ar
Ir
N N
Ar
Ir
N N
Ar
H
H
O
H
O
OH
2
H
H
H
H
O
H
O
+
Scheme 83 Cp*Ir catalysts used by Williams [242] for the TH of carbonyl compounds using
2-propanol as the hydrogen donor (top) and outer sphere metal-ligand bifunctional reaction
sequence (bottom)
144
M. Pilar Lamata et al.