their unprecedented reactivity in this field, which will be discussed in the text
(Scheme 1). This chapter will focus on a variety of sp
3 C–H functionalizations
catalyzed by different silver complexes.
2 Silver-Mediated Direct sp
3 C–H Transformations
2.1 Direct C–C Bond Formation
C–C bond formation is a major task in synthetic chemistry, and direct C–C bond
formation through sp
3 C–H transformation is an ideal method. Up to date, only a
few examples were reported via silver catalysts in this field. In 1996, Burgess and
coworkers described the earliest work of silver-mediated intramolecular carbene
insertion toward C–H bonds (Scheme 2) [14]. They examined 96 potential systems
of ligand/metal/solvent combinations to optimize such a C–H insertion reaction.
Silver hexafluoroantimonate(V) (AgSbF 6 ) together with bis(oxazolidine) ligand L*
in THF showed an unexpected activity and gave desired insertion products in
moderate yield (44%) and diastereoselectivity (2.7:1).
A family of tris(pyrazolyl)borate (Tp) silver complexes (Scheme 1, catalysts 1–
7) have been independently developed by Dias and Pe ´rez’s groups, which proved to
be efficient for carbene insertion in sp
3 C–H bonds with diazoacetates [8, 15–
24]. For example, in 2004, Dias, Lovely, and coworkers reported early examples of
carbene insertion into sp
3 C–H bond of alkanes and ethers by silver with tris
(pyrazolyl)borate complex 1 [18, 19]. In this reaction, using neat alkane as substrate
N
N
N
tBu
tBu
tBu
N
N
N
tBu
tBu
tBu
Ag
Ag
N
O
O
O
NO 3
N
N
N
N
Ag
Ag
O
O
Tf
Tf
[Ag(bp)OTf] 2 , 11
[Ag 2 (tBu 3 tpy) 2 (NO 3 )](NO 3 ), 10
N
N
CF 3
CF 3
N
N
CF 3
F 3 C
N
N CF 3
F3C
Ag
Ag
Ag
Ag 3 (m 2 -3,5-(CF 3 ) 2 PyrPy) 3 , 9
B
N
N
N
N
N
N
F 3 C
F 3 C
CF 3
CF 3
CF 3
CF 3
Ag
L
B
N
N
N
N
N
N
Br
Br
Br
Br
Br
Br
Ag
L
Br
Br
Br
[Tp*
,Br Ag] 2 , 8
Tp (CF3)2 Ag(THF), 1
[Tp
Br3 Ag] 2 (Me 2 CO), 2
F 21 -Tp 4Bo,3CF3 Ag(Me 2 CO), 3
R = CF 3
F 27 -Tp 4Bo,3CF2CF3 Ag(THF), 4
R = CF 2 CF 3
F 33 -Tp4Bo,3(CF 2)2CF3 Ag(Me 2 CO), 5
R = (CF 2 ) 2 CF 3
F 39 -Tp4Bo,3(CF 2)3CF3 Ag(THF or Me 2 CO), 6
R = (CF 2 ) 3 CF 3
F 51 -Tp4Bo,3(CF 2)5CF3 Ag(Me 2 CO), 7
R = (CF 2 ) 5 CF 3
B
N
N
N
N
N
N
Ag
Br
Br
Br
B
N
N
N
N
N
N
R
R
R
Ag
L
F
F
F
F
F
F
F
F
F
F
F
F
H
H
H
H
Scheme 1 Silver complexes involved in sp
3 C–H bond transformation
Silver-Mediated Direct sp
3 C–H Bond Functionalization
117
(Scheme 1). This chapter will focus on a variety of sp
3 C–H functionalizations
catalyzed by different silver complexes.
2 Silver-Mediated Direct sp
3 C–H Transformations
2.1 Direct C–C Bond Formation
C–C bond formation is a major task in synthetic chemistry, and direct C–C bond
formation through sp
3 C–H transformation is an ideal method. Up to date, only a
few examples were reported via silver catalysts in this field. In 1996, Burgess and
coworkers described the earliest work of silver-mediated intramolecular carbene
insertion toward C–H bonds (Scheme 2) [14]. They examined 96 potential systems
of ligand/metal/solvent combinations to optimize such a C–H insertion reaction.
Silver hexafluoroantimonate(V) (AgSbF 6 ) together with bis(oxazolidine) ligand L*
in THF showed an unexpected activity and gave desired insertion products in
moderate yield (44%) and diastereoselectivity (2.7:1).
A family of tris(pyrazolyl)borate (Tp) silver complexes (Scheme 1, catalysts 1–
7) have been independently developed by Dias and Pe ´rez’s groups, which proved to
be efficient for carbene insertion in sp
3 C–H bonds with diazoacetates [8, 15–
24]. For example, in 2004, Dias, Lovely, and coworkers reported early examples of
carbene insertion into sp
3 C–H bond of alkanes and ethers by silver with tris
(pyrazolyl)borate complex 1 [18, 19]. In this reaction, using neat alkane as substrate
N
N
N
tBu
tBu
tBu
N
N
N
tBu
tBu
tBu
Ag
Ag
N
O
O
O
NO 3
N
N
N
N
Ag
Ag
O
O
Tf
Tf
[Ag(bp)OTf] 2 , 11
[Ag 2 (tBu 3 tpy) 2 (NO 3 )](NO 3 ), 10
N
N
CF 3
CF 3
N
N
CF 3
F 3 C
N
N CF 3
F3C
Ag
Ag
Ag
Ag 3 (m 2 -3,5-(CF 3 ) 2 PyrPy) 3 , 9
B
N
N
N
N
N
N
F 3 C
F 3 C
CF 3
CF 3
CF 3
CF 3
Ag
L
B
N
N
N
N
N
N
Br
Br
Br
Br
Br
Br
Ag
L
Br
Br
Br
[Tp*
,Br Ag] 2 , 8
Tp (CF3)2 Ag(THF), 1
[Tp
Br3 Ag] 2 (Me 2 CO), 2
F 21 -Tp 4Bo,3CF3 Ag(Me 2 CO), 3
R = CF 3
F 27 -Tp 4Bo,3CF2CF3 Ag(THF), 4
R = CF 2 CF 3
F 33 -Tp4Bo,3(CF 2)2CF3 Ag(Me 2 CO), 5
R = (CF 2 ) 2 CF 3
F 39 -Tp4Bo,3(CF 2)3CF3 Ag(THF or Me 2 CO), 6
R = (CF 2 ) 3 CF 3
F 51 -Tp4Bo,3(CF 2)5CF3 Ag(Me 2 CO), 7
R = (CF 2 ) 5 CF 3
B
N
N
N
N
N
N
Ag
Br
Br
Br
B
N
N
N
N
N
N
R
R
R
Ag
L
F
F
F
F
F
F
F
F
F
F
F
F
H
H
H
H
Scheme 1 Silver complexes involved in sp
3 C–H bond transformation
Silver-Mediated Direct sp
3 C–H Bond Functionalization
117