D
M. A. Rajendra et al.
Letter
Synlett
verse nonaflates and pentafluorobenzene sulfonates and
propagated the synthesis of corresponding nitriles (Scheme
2). All the ONfs and OPFBs, irrespective of their electronic
properties, reacted well enough to furnish the desired ni-
triles in good to excellent yield.10
tributed to the facile oxidative addition of these electro-
philes using conventional palladium-catalyst systems like
Pd(PPh3)4 under very milder conditions as observed with
previous palladium-mediated reactions involving these
pseudohalides.11e,12
We have successfully performed a case study for finding
a suitable substrate for the palladium-catalyzed cyanation
reaction under mild conditions. The key findings of our
study paved the way for developing aryl nonaflates and
pentafluorobenzenesulfonates as effective substrates for
the proposed reaction. As a result, we developed an excep-
tionally mild protocol for the palladium-catalyzed cyana-
tion reaction to generate a series of cyanoarenes in good to
excellent yields. The developed protocol can be extended
for the synthesis of other complex nitriles in future.
X
CN
Pd(PPh3)4
Na2CO3
K4Fe(CN)6·3H2O
DMF
40 °C, 3 h
2
R
R
1g–h
3a–o
X = ONf, OPFB
CN
CN
CN
CN
CN
F
NH2
COOH
3d (85%)
3a (97%)
3b (91%)
3c (87%)
3e (95%)
Funding Information
X = OPFB
X = OPFB
X = OPFB
X = OPFB
X = OPFB
The authors are thankful to Sri Siddhartha Academy of Higher Educa-
tion and Karnataka Council for Technological Upgradation (KCTU) for
rendering all the facilities to carry out the research work. Vasiliy Ba-
kulev is thankful to the Russian Science Foundation (Grant No. 18-13-
CN
CN
CN
CN
CN
F
F
00161).
R
u
si
a
n
S
c
i
e
n
c
e
F
o
u
n
d
ati
o
n
(18-13-0
0
1
6
1)
OH
Br
F
CHO
3h (88%)
X = ONf
3f (92%)
X = ONf
3g (90%)
X = ONf
3i (93%)
3j (92%)
X = ONf
X = ONf
Supporting Information
CN
CN
Cl
CN
CN
CN
Supporting information for this article is available online at
F
F
S
u
p
p
orit
n
gInformati
o
n
S
u
p
p
orit
n
gInformati
o
n
CF3
NO2
Cl
F
F
Cl
3k (90%)
3l (89%)
X = ONf
3m (90%)
3n (94%)
3o (86%)
References and Notes
X = ONf
X = OPFB
X = OPFB
X = OPFB
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Scheme 2 Substrate scope of the developed protocol. Reagents and
conditions: Aryl nonaflate/pentafluorobenzenesulfonate (1 equiv),
K4FeCN6·3H2O (0.33 equiv), Pd(PPh3)4 (5 mol%), Na2CO3 (1 equiv) in dry
DMF, heated for 3 h at 40 ℃. Isolated yields after column chromatogra-
phy are given in parentheses.
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The diversity in the availability of phenols and its facile
conversion into the corresponding nonaflates or OPFBs em-
phasize the applicability of utilizing aryl OPFBs or nonaf-
lates as an alternative substrate in the palladium-catalyzed
cyanation reaction for obtaining aryl nitriles. The stability
of nonaflates and pentafluorobenzenesulfonates in the re-
action medium for palladium-catalyzed reactions has al-
ready been reported previously.11 The nonaflates are
known to suppress the O–S bond cleavage in the reaction
medium and thereby prevent its hydrolysis to the corre-
sponding phenols. The OPFBs are highly stable and more re-
active towards traditional palladium-catalyzed cross-cou-
pling reactions owing to its superior reactivity and stability.
In our successful trials, we have figured out that the use of
bench-stable and reactive ArOPFBs and ArONfs as electro-
philes resulted in good to excellent conversions under ex-
ceptionally milder conditions. This could be probably at-
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