4 FLP-Mediated C–H-Activation
127
NMe 2
O BCat
S BCat
E = -14.3 kcal mol
-1
G = -18.2 kcal mol
-1
E = -2.4 kcal mol
-1
G = -3.2 kcal mol
-1
= 8.0 kcal mol
-1
= 11.5 kcal mol
-1
E = 8.0 kcal mol
-1
= 9.3 kcal mol
-1
S
Int11
Int12
TS7
H
BCat
S
Me 2 N
H
BCat
O
Me 2 N
H
BCat
Me 2 N
H
BCat
O
Me 2 N
TS8
Δ
Δ
Δ
Δ
ΔE
ΔG
Δ
ΔG
Scheme 4.12 Calculated activation energies of the borylation step when catalysed by B(C 6 F 5 ) 3
H
Ar
2.) Pinacol, NEt 3
rt, 1 h
Ar BPin
BPin
Me 2 N
Me 2 N
BPin
N
BPin
Cl
Oestreich: 83%
Takita: 82%
a) or b)
Oestreich: 92%
Takita: 92%
Oestreich: 66%
Takita: 82%
a) Oestreich: B(C 6 F 5 ) 3 (5 mol%), HBCat (1.5 equiv.), 120 °C, 48 h, DCE
b) Takita: B(C 6 F 5 ) 3 (10 mol%), THT (10 mol%), HBCat (1 equiv.), 80 °C, 96 h, DCE
N
Me
BPin
Oestreich: 32%
Scheme 4.13 Selected scope comparison between the catalytic systems developed by the Oestreich
and Takita groups
H
Ar
2) pinacol, NEt 3
rt, 1 h
Ar BPin
N
TIPS
83%
BPin
N
TIPS
83%
BPin
N
TIPS
83%
BPin
N
TIPS
BPin
55%
1) B(C 6 F 5 ) 3 (10 mol%)
HBCat (4.0 equiv.)
120 °C, 72 h, toluene
Scheme 4.14 Borylation of various heteroarenes catalysed by B(C 6 F 5 ) 3