44
3 Theoretical Study of Rh-Catalyzed …
3-97
3-109
0.0
-0.3
G(M06, toluene)
(kcal/mol)
3-110ts
27.0
3-111
12.4
C-H bond cleavage
3-112ts
24.5
migratory insertion
3-113
-2.4
3-114ts
28.3
3-97
-12.4
reductive elimination
= dppe
3-97
K 3 PO 4
CONMe 2
N
CF 3
+ KCl
3-106
3-106
3-106
3-109
3-110ts
3-112ts
3-113
3-114ts
K 3 PO 4
N
F 3 C
3-115 CONMe 2
+
3-106 + KCl
3-119ts
41.3
3-117
-2.8
3-118
21.4
4.2
3-116
K 3 PO 4
3-116
3-117
3-118
3-119ts
HOPiv + KCl
3-111
Rh
Cl
P
P
N
CF 3
Rh
P
P
P
P
K
O
O P
O
O
K
Rh
Cl
P
P
K
K
O
O
P
O
O
K
N
CF 3
H
Rh
Cl
P
P
K
K
O
HO
P
O
O
K
N
CF 3
Rh
P
P
N
CF 3
CONMe 2
Rh
P
P
N
CF 3
CONMe 2
Rh
P
P
N
CF 3
CONMe 2
K
O
HO P O
O K
Rh
P
P
N
CF 3
K
O
O
P
O
O
K
H
3-111
Rh
P
P
N
CF 3
CONMe 2
K
O
O
P
O
O
K
Rh
P
P
N
CF 3
K
O
O
P
O
O
K
H
CONMe 2
Rh
P
P
K
O
O
P
O
O
K
N
CF 3
H
Fig. 3.25 Free energy profiles for the Rh(I)-catalyzed C-H activation and ortho-alkylation of unactivated azines with acrylamide using K 3 PO 4 as base. The values are the relative free energies given
in kcal/mol calculated at the M06/6-31G(d,p)/SDD//B3-LYP/6-31G(d,p)/LANL2DZ level of theory
in toluene
transfer also plays a particularly important role to complete the formal alkylation
reaction (Scheme 3.26).
The free energy profiles for the preferred pathway considering by DFT calculation
for this reaction are given in Fig. 3.27 [55]. The cationic Cp*Rh(III) acetate complex
3-120 was set to the relative zero value for the reaction pathway. The N-oxidedirected CMD type C–H bond cleavage takes place via a six-membered ring-type
transition state 3-123ts with an activation free energy of 23.3 kcal/mol resulting in
aryl-Rh intermediate 3-124. The subsequent insertion of the coordinated acetylene
into Rh–C(aryl) bond occurs via transition state 3-126ts with an energy barrier of
18.1 kcal/mol to generate rhodacyclic 3-127. The following C–O bond reductive
4 mol % [Cp*RhCl 2 ] 2
16 mol % AgSbF 6
2 eq. AcOH
1,4-dioxane, 110 C, 20h
+
38 - 92 % yield
N
O
Ar
Ar
N
Ar
O
Ar
Scheme 3.26 Rh(III)-catalyzed C–H activation and ortho-alkylation of quinoline N-oxide with
alkynes
3 Theoretical Study of Rh-Catalyzed …
3-97
3-109
0.0
-0.3
G(M06, toluene)
(kcal/mol)
3-110ts
27.0
3-111
12.4
C-H bond cleavage
3-112ts
24.5
migratory insertion
3-113
-2.4
3-114ts
28.3
3-97
-12.4
reductive elimination
= dppe
3-97
K 3 PO 4
CONMe 2
N
CF 3
+ KCl
3-106
3-106
3-106
3-109
3-110ts
3-112ts
3-113
3-114ts
K 3 PO 4
N
F 3 C
3-115 CONMe 2
+
3-106 + KCl
3-119ts
41.3
3-117
-2.8
3-118
21.4
4.2
3-116
K 3 PO 4
3-116
3-117
3-118
3-119ts
HOPiv + KCl
3-111
Rh
Cl
P
P
N
CF 3
Rh
P
P
P
P
K
O
O P
O
O
K
Rh
Cl
P
P
K
K
O
O
P
O
O
K
N
CF 3
H
Rh
Cl
P
P
K
K
O
HO
P
O
O
K
N
CF 3
Rh
P
P
N
CF 3
CONMe 2
Rh
P
P
N
CF 3
CONMe 2
Rh
P
P
N
CF 3
CONMe 2
K
O
HO P O
O K
Rh
P
P
N
CF 3
K
O
O
P
O
O
K
H
3-111
Rh
P
P
N
CF 3
CONMe 2
K
O
O
P
O
O
K
Rh
P
P
N
CF 3
K
O
O
P
O
O
K
H
CONMe 2
Rh
P
P
K
O
O
P
O
O
K
N
CF 3
H
Fig. 3.25 Free energy profiles for the Rh(I)-catalyzed C-H activation and ortho-alkylation of unactivated azines with acrylamide using K 3 PO 4 as base. The values are the relative free energies given
in kcal/mol calculated at the M06/6-31G(d,p)/SDD//B3-LYP/6-31G(d,p)/LANL2DZ level of theory
in toluene
transfer also plays a particularly important role to complete the formal alkylation
reaction (Scheme 3.26).
The free energy profiles for the preferred pathway considering by DFT calculation
for this reaction are given in Fig. 3.27 [55]. The cationic Cp*Rh(III) acetate complex
3-120 was set to the relative zero value for the reaction pathway. The N-oxidedirected CMD type C–H bond cleavage takes place via a six-membered ring-type
transition state 3-123ts with an activation free energy of 23.3 kcal/mol resulting in
aryl-Rh intermediate 3-124. The subsequent insertion of the coordinated acetylene
into Rh–C(aryl) bond occurs via transition state 3-126ts with an energy barrier of
18.1 kcal/mol to generate rhodacyclic 3-127. The following C–O bond reductive
4 mol % [Cp*RhCl 2 ] 2
16 mol % AgSbF 6
2 eq. AcOH
1,4-dioxane, 110 C, 20h
+
38 - 92 % yield
N
O
Ar
Ar
N
Ar
O
Ar
Scheme 3.26 Rh(III)-catalyzed C–H activation and ortho-alkylation of quinoline N-oxide with
alkynes