Chemistry Reference
In-Depth Information
O
O
OH
H
O
Rh(COD)
2
OTf
O
R
1
O
O
S
R
2
R
2
+
R
1
P
O
Abbas-Phos
-1
Li
2
CO
3
H
2
(1 atm)
DCM, 25°C
H
59
60
61
AbbasPhos-I
R
1
R
2
Entry
Yield (%) of
61
syn
:
anti
% ee
a
Me
phthalimido
88
50:1
96
Et
Et
phthalimido
94
45:1
95
b
c
Me
OBn
85
25:1
91
d
Me
Ph
70
25:1
90
e
f
g
Et
Et
Et
Ph
76
22:1
90
Et
3-furyl
83
25:1
88
Me
3-
N-
methylindolyl
92
15:1
86
h
Me
3-
N-
methylindolyl
97
25:1
90
Scheme 8C.24.
Rh(CO D)
2
OTf (3-5 mol %)
Chiral ligand (3-5 mol %)
H
2
(1 atm)
R
1
R
1
Y
Y
X
R
2
X
Dichloroethane, 25°C, 2-3h
R
2
H
63
62
R
1
R
2
X
Y
Ligand
Yield (%) of
63
% ee
a
Me
H
TsN
CH
2
(
R
)-BINAP
79
93
b
Ph
H
O
CH
2
(
R
)-BINAP
80
97
Ph
H
O
CMe
2
(
R
)-Cl-OMe-BIPHEP
85
84
c
d
HO(CH
2
)
2
H
O
CH
2
(
R
)-Cl-OMe-BIPHEP
77
95
e
BnO(CH
2
)
2
H
O
CH
2
(
R
)-BINAP
77
98
f
BnO(CH
2
)
2
H
O
CMe
2
(
R
)-Cl-OMe-BIPHEP
82
98
g
Me
H
BnN
CO
(
R
)-PHANEPHOS
73
91
h
Me
H
O
CO
(
R
)-PHANEPHOS
73
94
i
CO
2
Me
c
-PrCO
CH
2
CH
2
(
R
)-Cl-OMe-BIPHEP
68
98
j
CO
2
Me
PhCO
CH
2
CH
2
(
R
)-BINAP
66
96
k
CO
2
Me
2-furan-CO
CH
2
CH
2
(
R
)-BINAP
72
96
CO
2
Me
3,4-Cl
2
C
6
H
3
CO
CH
2
CH
2
(
R
)-BINAP
63
94
l
Scheme 8C.25.
in those reactions resulted in either formation of a mixture of multiple products or
complete reduction of the substrates.
A plausible mechanism of this reaction was proposed on the basis of deuterium label-
ing control experiments [36]. As Scheme 8C.26 illustrates, the catalytic cycle begins with
cycloaddition of an RhL
n
species and enyne
62
(R
2
= H), forming rhodacyclopentene
64
. Homolytic hydrogen activation via either oxidative addition of molecular hydrogen
or σ-bond metathesis takes place to yield vinyl-rhodium vinyl species
65
. The subsequent
