A New Rhodium/Copper-Cocatalyzed C-H Oxidation for the Preparation of Isoquinolin-1-ones

Article abstract of DOI:10.1055/s-0035-1561947

A new and efficient rhodium/copper-cocatalyzed C-H oxidation reaction of isoquinolinium N-amides has been developed. In the presence of rhodium(II) acetate dimer, copper(II) chloride, a ligand and sodium tert-butoxide, a variety of isoquinolin-1-ones were prepared in moderate to good yields via ortho C-H oxidation.

Full text of DOI:10.1055/s-0035-1561947

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2016, 48, A–H
paper
A
Z.-L. Zhou et al.
Paper
Synthesis
A New Rhodium/Copper-Cocatalyzed C–H Oxidation for the
Preparation of Isoquinolin-1-ones
Zeng-Le Zhoua
Yi-Lin Liu*b
Jian-Lan Songa
Chen-Liang Deng*a
H
18O
NR3
Rh2(OAc)4, CuCl2
ligand, NaOtBu
DMF (anhydrous), H218O
NHR3
N
N
R1
R1
R2
R2
air, 95 °C
a College of Chemistry and Materials Engineering, Wenzhou
University, Wenzhou 325035, P. R. of China
b Huaihua Key Laboratory of Functional Inorganic & Polymeric
Materials, Huaihua University, Huaihua 418008, P. R. of China
liuyilinhn@126.com
22 examples
up to 74% yield
R1, R2 = alkyl, halide, alkoxy
R
3 = Boc, Ts, Bz
dcl78@wzu.edu.cn
Received: 09.11.2015
Accepted after revision: 23.02.2016
Published online: 08.04.2016
NH2
O
N
O
N
O
NH
DOI: 10.1055/s-0035-1561947; Art ID: ss-2015-h0650-op
R
COOMe
Abstract A new and efficient rhodium/copper-cocatalyzed C–H oxida-
tion reaction of isoquinolinium N-amides has been developed. In the
presence of rhodium(II) acetate dimer, copper(II) chloride, a ligand and
sodium tert-butoxide, a variety of isoquinolin-1-ones were prepared in
moderate to good yields via ortho C–H oxidation.
R'
topoisomeras I inhibitors
.H2SO4
HO
H
MeO
OMe
O
OMe
O
T-1032
OH
H
O
HO
OH
O
O
Key words rhodium(II) acetate dimer, copper(II) chloride, isoquinolin-
ium N-amides, C–H oxidation, isoquinolin-1-ones
Me
O
N
N
OMe
O
O
Sch 56036
O
Nitrogen-containing heterocycles are the key compo-
nents of many bioactive natural products and potent
drugs.1 The isoquinolin-1-ones, an important class of het-
erocyclic compounds, make up the core structures of sever-
al alkaloids and pharmacologically active compounds such
as those shown in Figure 1.2 Due to their chemical stability,
isoquinolin-1-one units are regularly used as building
blocks in organic synthesis, and have also received signifi-
cant interest in medicinal chemistry.3
During the past decades, the transition-metal-catalyzed
functionalization of C–H bonds in an atom-economic fash-
ion has attracted much attention in organic synthesis.4
Transition-metal-catalyzed ortho C–H oxidation represents
a powerful tool for the formation of isoquinolin-1-ones,5
and a variety of different directing groups and catalysts
have been extensively explored in terms of their impact on
this transformation.6 Several recent studies have outlined
the use of rhodium-catalyzed ortho C–H oxidation reactions
for the construction of an isoquinolin-1-one skeleton. For
example, Li and co-workers reported a method for the
preparation of isoquinolones from benzamides and alkynes
via a rhodium-catalyzed ortho C–H oxidation (Scheme 1, eq
1).7 Hyster and Rovis utilized the rhodium-catalyzed oxida-
isoquinolinone alkaloid
of Corydalis bungeana
Figure 1 Compounds containing the isoquinolin-1-one motif
tive cycloaddition of benzamides and alkynes for the con-
struction of isoquinolones (Scheme 1, eq 2).8 Although both
of these reactions involve the use of an amide directing
group with high activity, these methods generally suffer
from some limitations, including harsh reaction conditions
or a stoichiometric amount of oxidant. To address these
drawbacks, the development of an efficient, milder, envi-
ronmentally benign and highly regioselective C–H oxida-
tion reaction9 still remains an outstanding challenge. Here-
in, we report a new and efficient rhodium/copper-cocata-
lyzed ortho C–H oxidation reaction for the synthesis of
isoquinolin-1-one derivatives (Scheme 1, eq 3). Interesting-
ly, this reaction involves the use of an N-amide directing
group.
As shown in Table 1, the reaction of 3-phenylisoquino-
linium-2-yl amide 1a was used as a model reaction to de-
termine the optimal reaction conditions. When 1a in tolu-
ene was heated at 95 °C for 24 hours under air in the pres-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

B
Z.-L. Zhou et al.
Paper
Synthesis
Table 1 Screening for the Optimal Reaction Conditionsa
O
R
Li's work
O
R
R
[Cp*RhCl2]2
Ag2CO3
R2
R
R2
N
O
N
O
R1
eq 1
eq 2
R1
H
MeCN, 115 °C
NHBoc
NBoc
Ph
catalyst
N
N
N
+
Rovis' work
air, 95 oC, 24 h
O
Ph
Ph
Ph
R2
[Cp*RhCl2]2
Cu(OAc)2
R2
N
1a
2a
3a
N
R1
R1
H
t-AmOH, 110 °C
Ph
Entry Catalyst
Ligand Base
Solvent
Yieldb (%)
Ph
18O
Ph
This work
R1
NR3
Rh2(OAc)4, CuCl2
ligand, base
NHR3
2a
45
3a
17
N
N
R1
eq 3
DMF–H218O, air, 95 °C
1
2
Rh2(OAc)4
L1
NaOt-Bu
NaOt-Bu
–
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
xylene
DMA
R2
R2
–
L1
L1
L1
L1
L1
L2
L3
L1
L1
L1
L1
L1
L1
L1
L1
0
0
11
3
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
RhCl3
15
Scheme 1 Selected strategies for the preparation of isoquinolin-1-
ones
4
KOt-Bu
34
39
0
17
5
LiOt-Bu
Cs2CO3
22
6
26
ence of Rh2(OAc)4 (3 mol%), IMes·HCl (L1, 6 mol%) and
NaOt-Bu (2.5 equiv), the desired 3-phenylisoquinolin-
1(2H)-one product 2a was formed in 45% yield together
with the reduced byproduct 3-phenylisoquinoline (3a) in
17% yield (Table 1, entry 1). The structure of product 2a was
confirmed by single-crystal X-ray diffraction analysis (Fig-
ure 2). When the reaction was conducted in the absence of
rhodium or base, none of the target product 2a was ob-
served; only 11% or 15% yield of 3a was obtained, demon-
strating that the rhodium and base play a critical role in this
oxidation (Table 1, entries 2 and 3). Encouraged by this re-
sult, we proceeded to evaluate several different bases, in-
cluding KOt-Bu, LiOt-Bu and Cs2CO3 (Table 1, entries 4–6).
The results revealed that the use of NaOt-Bu as base provid-
ed the highest yield of the desired product. Several other li-
gands (Figure 3), such as Bu3P·HBF4 (L2) and 1,3-bis(2,6-di-
isopropylphenyl)-4,5-dihydroimidazolium tetrafluorobo-
rate (L3), were also investigated (Table 1, entries 7 and 8);
they were less effective than IMes·HCl (L1). Screening also
revealed that three other rhodium species, namely RhCl3,
[Cp*RhCl2]2 and (Ph3P)3RhCl, have reactivity to catalyze the
7
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
NaOt-Bu
22
25
21
38
10
36
48
50
63
74
64
10
60
52
29
8
24
9
15
10
11
12
13
14
15
16
17
18
19c
[Cp*RhCl2]2
(Ph3P)3RhCl
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4 + CuCl
Rh2(OAc)4 + CuCl2
23
25
27
trace
trace
trace
<5
DMF
DMF
DMF
Rh2(OAc)4 + Cu(OAc)2 L1
DMF
trace
7
CuCl2
L1
L1
L1
DMF
Rh2(OAc)4 + CuCl2
DMF
trace
<5
20d Rh2(OAc)4 + CuCl2
DMF
a Reaction conditions: 1a (0.4 mmol), [Rh] (3 mol%), [Cu] (3 mol%), ligand (6
mol%), base (2.5 equiv), solvent (3 mL), 95 °C, under air, 24 h.
b Isolated yield.
c Conducted at 80 °C.
d Conducted at 120 °C.
oxidation (Table 1, entries 9–11), although they were less
efficient than Rh2(OAc)4. Subsequently, a series of solvents
(xylene, DMA, DMF) were investigated, with DMF medium
providing the best result (Table 1, entries 12–14). Interest-
ingly, product 2a was selectively furnished in moderate
yield, together with only trace amounts of byproduct 3a,
when polar solvents were used (Table 1, entries 13 and 14).
To our surprise, the addition of CuCl (3 mol%) to the reac-
N
N
N+
N+
Bu3P·HBF4
–BF4
Cl–
L1
L2
L3
Figure 2 ORTEP diagram of the single-crystal X-ray structure of com-
pound 2a
Figure 3
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

C
Z.-L. Zhou et al.
Paper
Synthesis
tion mixture led to a significant increase in the yield of de-
sired product 2a (Table 1, entry 15). Based on these results,
we also investigated two other copper salts, namely CuCl2
and Cu(OAc)2. Both of these salts promoted the yield of 2a,
with CuCl2 providing the highest yield of 74% (Table 1, en-
tries 16 and 17). However, the yield of 2a was dramatically
decreased to 10% when CuCl2 was used independently as
the catalyst (Table 1, entry 18). Finally, the reaction tem-
perature was also investigated. When the oxidation was
performed at 80 °C or 120 °C, there was a significant de-
crease in the yield of 2a (Table 1, entries 19 and 20).
With the optimal reaction conditions in hand, a variety
of substrates 1 were examined, and the results are summa-
rized in Scheme 2. Initially, the electronic effects of R1
groups on the isoquinoline ring were examined. The results
indicated that several functional groups, both electron do-
nating and electron deficient, are well-tolerated. Com-
pounds bearing an electron-deficient group, such as the
chloro-, trifluoromethyl- and fluoro-substituted substrates,
underwent the transformation in good yields, providing the
target products 2b, 2d and 2e in 68%, 71% and 51% yield, re-
spectively. Electron-donating groups, such as in methoxy-
or methyl-substituted substrates 1, are also well-tolerated;
O
Rh2(OAc)4 (3 mol%)
CuCl2 (3 mol%)
IMes⋅HCl (6 mol%)
NHR3
NR3
N
N
R1
R1
NaOtBu (2.5 equiv)
DMF (3 mL), air
95 °C, 36 h
2r–w
1r–w
(0.4 mmol)
O
O
O
NHBz
NHTs
NHBoc
N
N
N
2r, 50%, 36 h
2s, 35%, 36 h
2t, 63%, 36 h
O
O
O
N
NHTs
NHBoc
NHAc
N
N
F
F
2u, 48%, 36h
2v, 54%, 36 h
2w, no product, 48 h
Scheme 3 Regioselective rhodium/copper-cocatalyzed reaction of iso-
quinolinium-2-yl amides 1r–v
the corresponding products 2c, 2f and 2g were provided in
moderate yields. Subsequently, we proceeded to evaluate
the impact of different R2 groups on the aromatic ring (at
the 3-position) of 1 and found that the reaction of sub-
strates bearing electron-withdrawing groups at the para
position proceeded quickly to give the target products 2h
and 2i in 68% and 67% yield, respectively. However, an elec-
tron-donating group led to a slightly lowered 60% yield of
2j. The impact of steric hindrance and electronic effects re-
sulting from substituent R2 was also evaluated with meth-
oxy- and methyl-substituted substrates; the order of activi-
ty was determined to be para > ortho > meta in terms of
yields (2j–m). Finally, a series of isoquinolines 1 bearing
different R3 groups (replacing Boc) on the nitrogen atom
were examined under the optimized conditions. The results
demonstrated that R3 groups such as benzoyl, tosyl and
phenylsulfonyl are also compatible, with the corresponding
N-substituted isoquinolinone products being formed in
moderate to good yields (2n–p). Unfortunately, only 14%
yield of target product 2q was obtained when R3 was an
acetyl group. The reaction did not work when 3-butyliso-
quinolinium-2-yl tert-butoxycarbonylamide was used as
substrate in the transformation.
To our delight, during the workup process we discov-
ered that the catalytic system is highly regioselective, as
shown in Scheme 3. When isoquinolinium-2-yl amides 1r–
v were subjected to the reaction under the optimal condi-
tions, they afforded the corresponding products 2r–v in
which selective oxidation took place at the 1-position, with
none of the 3-position oxidation product being observed,
demonstrating the high regioselectivity of this oxidation.
For instance, treatment of substrates 1r–t under the opti-
mal conditions generated the desired products 2r–t in 50%,
35% and 63% yield, respectively. Fluoro-containing sub-
strates 1u and 1v were compatible with the optimal condi-
O
Rh2(OAc)4 (3 mol%)
CuCl2 (3 mol%)
IMes⋅HCl (6 mol%)
NR3
NHR3
N
N
R1
R1
NaOtBu (2.5 equiv)
DMF (3 mL), air
95 °C, 20–36 h
R2
R2
2b–q
1b–q
(0.4 mmol)
O
O
R1
NHBoc
R1 = Cl, 2b, 68% (24 h)
R1 = OMe, 2c, 64% (30 h)
R1 = CF3, 2d, 71% (20 h)
N
N
Ph
NHBoc
R1 = F, 2e, 51% (24 h)
R1 = Me, 2f, 48% (36 h)
R1
Ph
O
MeO
NHBoc
2g, 66% (36 h)
N
MeO
Ph
O
O
R2 = 4-Cl, 2h, 68% (24 h)
R2 = 4-CN, 2i, 67% (24 h)
R2 = 4-OMe, 2j, 60% (30 h)
R2 = 2-OMe, 2k, 50% (36 h)
R2 = 2-Me, 2l, 53% (36 h)
R2 = 3-Me, 2m, 39% (36 h)
NHBoc
N
N
R2
R3 = Bz, 2n, 66% (30 h)
R3 = Ts, 2o, 48% (36 h)
R3 = SO2Ph, 2p, 42% (36 h)
R3 = Ac, 2q, 14% (36 h)
NHR3
Ph
O
NHR3
R3 = Boc, no product (48 h)
N
Bu
Scheme 2 Rhodium/copper-cocatalyzed reaction of 3-arylisoquinolini-
um-2-yl amides 1b–q
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

D
Z.-L. Zhou et al.
Paper
Synthesis
tions, providing 2u and 2v in moderate yields. However,
when R3 was an acetyl group, the reaction failed to provide
the desired product 2w.
ate amount of water is important in the reaction. Excess
water probably lowers the concentration of base, and hy-
drolysis of the catalysts leads to a lower yield of target
product.
To determine the source of the oxygen atom in the prod-
ucts, an 18O-labeling experiment was carried out (Scheme
4). In the presence of Rh2(OAc)4, CuCl2, IMes·HCl, NaOt-Bu,
anhydrous DMF and H218O (0.1 mL), the reaction gave the
18O-containing product [1-18O]-2a in 50% yield. This control
experiment confirmed that the oxygen atom of the product
is derived from aqueous DMF. We also performed a control
experiment under the standard conditions in anhydrous
DMF, and only a trace amount of the corresponding product
2a was obtained (Scheme 5). This implies that the appropri-
Based on previous reports,4d,7,10 as well as our results, a
possible mechanism for the oxidation reaction of 1a is pro-
posed, as outlined in Scheme 6. The initial combination of
Rh2(OAc)4 with the ligand would give a rhodium species,
which on coordination to the substrate 1a provides the in-
termediate A. With the assistance of NaOt-Bu, the intramo-
lecular insertion of rhodium into the C–H bond at the 1-po-
sition of A would lead to the formation of intermediate B
together with byproducts.11 Subsequently, nucleophilic at-
tack of intermediate B by H2O as the nucleophilic reagent
affords intermediate C; meanwhile, regeneration of the
rhodium species with copper salt as oxidant would com-
plete the catalytic cycle. Finally, the target product 2a could
be obtained from intermediate C via tautomerization. An-
other possible pathway is that H2O as the nucleophilic re-
agent directly attacks the iminium intermediate A, result-
ing in formation of the water-addition product D which is
further oxidized by copper/air to afford product 2a.
In summary, we have developed a new and efficient
method for the rhodium/copper-cocatalyzed C–H oxidation
of isoquinolinium N-amides. This new method involves the
use of the N-amide group as a directing moiety. Important-
ly, this protocol could be applied to the synthesis of iso-
quinolin-1-ones, making it particularly attractive for use in
studies involving organic synthesis and medicinal chemis-
try. Work to extend the scope and application of this reac-
tion is currently underway.
18O
Rh2(OAc)4 (3 mol%)
CuCl2 (3 mol%)
IMes⋅HCl (6 mol%)
NBoc
Ph
NHBoc
Ph
N
N
NaOtBu (2.5 equiv)
DMF (anhydrous)
H218O (0.1 mL)
air, 95 °C, 24 h
[1-18O]-2a 50%
1a
Scheme 4 18O-Labeling experiment
Rh2(OAc)4 (3 mol%)
CuCl2 (3 mol%)
O
NBoc
Ph
NHBoc
IMes⋅HCl (6 mol%)
N
N
NaOtBu (2.5 equiv)
DMF (anhydrous)
air, 95 °C, 24 h
Ph
2a, trace
1a
Scheme 5 Control experiment (anhydrous conditions)
2a
tautomerization
Rh2(OAc)4
O
N
OtBu
ligand
N
O
OtBu
O2
OH
CuI
Ln Rh(OAc)2
N
N
Ph
CuII
1a
Ph
C
Ln
H
H2O
Rh(OAc)2
Ln
O
OtBu
O
OtBu
AcOH
Rh
OAc
AcO
Ln
N
Rh
O
N
N
N
OtBu
H
Ph
HO
Ph
B
N
A
H2O
N
NaOtBu
Ph
D
CuII
CuI
tBuOH
NaOAc
O2
2a
Scheme 6 Proposed mechanism for the oxidation
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

E
Z.-L. Zhou et al.
Paper
Synthesis
Chemicals were either used as purchased or purified by standard
techniques. 1H NMR and 13C NMR spectra were measured on a Bruker
Avance III 500-MHz spectrometer (1H: 500 MHz, 13C: 125 MHz), using
CDCl3 as the solvent with TMS as internal standard at r.t. Chemical
shifts are given in δ relative to TMS and the coupling constants J are
given in Hz. High-resolution mass spectra were recorded on a Bruker
micro TOF QII ESI-Q-TOF mass spectrometer. IR spectra were recorded
on a Nicolet iS10 spectrophotometer (Thermo Scientific). Melting
points were measured using a Colid X-4 apparatus (Beijin TECH). All
reactions were conducted under air atmosphere using standard
Schlenk techniques. Column chromatography was performed using
EM silica gel 60 (300–400 mesh).
13C NMR (125 MHz, CDCl3): δ = 161.6, 158.6, 155.2, 142.5, 134.6,
130.7, 129.1, 129.0, 128.6, 127.9, 126.0, 123.6, 108.0, 107.0, 82.3, 55.7,
27.9.
HRMS (ESI): m/z [M + H]+ calcd for C21H23N2O4: 367.1652; found:
367.1651.
tert-Butyl (1-Oxo-3-phenyl-7-(trifluoromethyl)isoquinolin-2(1H)-
yl)carbamate (2d)
White solid; yield: 114.7 mg (71%); mp 186.6–188.4 °C.
IR (KBr): 2974, 1746, 1656, 1627, 1514, 1371, 1322, 1242, 1126 cm–1
.
1H NMR (500 MHz, CDCl3): δ = 8.53 (s, 1 H), 7.71 (d, J = 8.0 Hz, 1 H),
7.49 (d, J = 8.5 Hz, 1 H), 7.42 (d, J = 7.5 Hz, 2 H), 7.36–7.32 (m, 3 H),
7.26 (br s, 1 H), 6.42 (s, 1 H), 1.29 (s, 9 H).
Isoquinolin-1-ones 2a–v; General Procedure
13C NMR (125 MHz, CDCl3): δ = 161.6, 154.8, 147.4, 139.2, 134.1,
129.2, 129.0 (q, JC–F = 3.5 Hz), 128.9, 128.5 (q, JC–F = 32.5 Hz), 128.0,
127.0, 125.8 (q, JC–F = 7.5 Hz), 124.4, 123.8 (q, JC–F = 270.0 Hz), 106.4,
82.6, 27.9.
HRMS (ESI): m/z [M + H]+ calcd for C21H20N2O3F3: 405.1421; found:
405.1415.
To a Schlenk tube were added an isoquinolinium-2-yl amide 1 (0.4
mmol), Rh2(OAc)4 (5.3 mg, 3 mol%), CuCl2 (1.6 mg, 3 mol%), IMes·HCl
(8.2 mg, 6 mol%) and NaOt-Bu (96.1 mg, 2.5 equiv) in DMF (3 mL).
Then, the tube was stirred at 95 °C (oil bath temperature) under air
atmosphere for the indicated time (see Schemes 2 and 3) until com-
plete consumption of starting material, as monitored by TLC and GC-
MS analysis. After the reaction was finished, the reaction mixture was
cooled to r.t., diluted with EtOAc and washed with brine. The aqueous
phase was re-extracted with EtOAc. The combined organic extracts
were dried over Na2SO4 and concentrated under reduced pressure.
The residue was then purified via silica gel chromatography (hexane–
EtOAc) to afford the corresponding isoquinolin-1-one product 2.
tert-Butyl (6-Fluoro-1-oxo-3-phenylisoquinolin-2(1H)-yl)carba-
mate (2e)
White solid; yield: 72.2 mg (51%); mp 198.7–200.7 °C.
IR (KBr): 2959, 1746, 1656, 1607, 1484, 1245, 1149 cm–1
.
1H NMR (500 MHz, CDCl3): δ = 8.38 (dd, J = 8.5, 5.5 Hz, 1 H), 7.51–7.49
(m, 2 H), 7.43–7.39 (m, 4 H), 7.16–7.10 (m, 2 H), 6.41 (s, 1 H), 1.36 (s,
9 H).
tert-Butyl (1-Oxo-3-phenylisoquinolin-2(1H)-yl)carbamate (2a)
White solid; yield: 99.5 mg (74%); mp 174.6–176.0 °C.
IR (KBr): 2974, 1749, 1646, 1617, 1524, 1368, 1245, 1149, 1053 cm–1
.
13C NMR (125 MHz, CDCl3): δ = 165.6 (d, JC–F = 251.2 Hz), 161.3, 155.1,
146.3, 138.9 (d, JC–F = 10.0 Hz), 136.3, 134.2, 131.5 (d, JC–F = 10.1 Hz),
129.0, 127.9, 121.5, 115.3 (d, JC–F = 23.7 Hz), 111.0 (d, JC–F = 21.2 Hz),
106.4, 82.3, 27.9.
HRMS (ESI): m/z [M + H]+ calcd for C20H20N2O3F: 355.1452; found:
355.1444.
1H NMR (500 MHz, CDCl3): δ = 8.37 (d, J = 8.0 Hz, 1 H), 7.61 (t, J = 7.5
Hz, 1 H), 7.55 (s, 1 H), 7.52–7.51 (m, 2 H), 7.46–7.38 (m, 5 H), 6.46 (s, 1
H), 1.35 (s, 9 H).
13C NMR (125 MHz, CDCl3): δ = 162.0, 155.1, 144.8, 136.5, 134.4,
132.8, 129.0, 128.6, 128.1, 127.8, 126.5, 126.0, 124.8, 107.1, 81.9, 27.8.
HRMS (ESI): m/z [M + H]+ calcd for C20H21N2O3: 337.1547; found:
337.1541.
tert-Butyl (6-Methyl-1-oxo-3-phenylisoquinolin-2(1H)-yl)carba-
mate (2f)
White solid; yield: 67.3 mg (48%); mp 148.5–149.9 °C.
IR (KBr): 2972, 1749, 1650, 1626, 1491, 1245, 1156 cm–1
.
tert-Butyl (7-Chloro-1-oxo-3-phenylisoquinolin-2(1H)-yl)carba-
mate (2b)
1H NMR (500 MHz, CDCl3): δ = 8.19 (d, J = 8.5 Hz, 1 H), 7.44–7.42 (m, 2
H), 7.33–7.29 (m, 4 H), 7.19 (d, J = 6.5 Hz, 2 H), 6.33 (s, 1 H), 2.38 (s, 3
H), 1.30 (s, 9 H).
White solid; yield: 100.7 mg (68%); mp 186.7–188.4 °C.
IR (KBr): 2960, 1743, 1646, 1613, 1587, 1477, 1365, 1245, 1152, 1066
cm–1
.
13C NMR (125 MHz, CDCl3): δ = 161.9, 155.2, 144.8, 143.6, 136.7,
134.6, 129.0, 128.6, 128.2, 128.1, 127.8, 125.9, 122.6, 107.0, 82.0, 27.9,
21.8.
HRMS (ESI): m/z [M + H]+ calcd for C21H23N2O3: 351.1703; found:
351.1697.
1H NMR (500 MHz, CDCl3): δ = 8.32 (d, J = 2.5 Hz, 1 H), 7.57 (dd,
J = 8.5, 2.0 Hz, 1 H), 7.50 (dd, J = 7.0, 2.0 Hz, 2 H), 7.43–7.41 (m, 4 H),
7.32 (br s, 1 H), 6.45 (s, 1 H), 1.38 (s, 9 H).
13C NMR (125 MHz, CDCl3): δ = 161.0, 155.0, 145.3, 134.9, 134.2,
133.4, 132.6, 129.0 (2 C), 128.0, 127.7, 127.5, 125.9, 106.5, 82.4, 27.9.
HRMS (ESI): m/z [M + H]+ calcd for C20H20N2O3Cl: 371.1157; found:
371.1155.
tert-Butyl (6,7-Dimethoxy-1-oxo-3-phenylisoquinolin-2(1H)-
yl)carbamate (2g)
White solid; yield: 104.5 mg (66%); mp 188.5–190.3 °C.
IR (KBr): 2968, 1736, 1646, 1593, 1507, 1404, 1242, 1152, 1040 cm–1
.
tert-Butyl (7-Methoxy-1-oxo-3-phenylisoquinolin-2(1H)-yl)carba-
mate (2c)
1H NMR (500 MHz, CDCl3): δ = 7.74 (s, 1 H), 7.50 (dd, J = 7.0, 2.5 Hz, 2
H), 7.40 (dd, J = 5.0, 2.0 Hz, 3 H), 7.23 (br s, 1 H), 6.84 (s, 1 H), 6.40 (s, 1
H), 3.97 (s, 6 H), 1.40 (s, 9 H).
White solid; yield: 93.7 mg (64%); mp 197.0–198.8 °C.
IR (KBr): 2976, 1739, 1606, 1497, 1358, 1242, 1156, 1027 cm–1
1H NMR (500 MHz, CDCl3): δ = 7.81 (d, J = 2.5 Hz, 1 H), 7.51–7.49 (m, 2
H), 7.45 (d, J = 8.5 Hz, 1 H), 7.41–7.39 (m, 3 H), 7.28 (dd, J = 8.5, 2.5 Hz,
1 H), 7.04 (br s, 1 H), 6.47 (s, 1 H), 3.92 (s, 3 H), 1.41 (s, 9 H).
.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

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13C NMR (125 MHz, CDCl3): δ = 161.2, 155.5, 153.9, 149.0, 143.4,
134.6, 132.2, 129.1, 128.6, 127.8, 118.6, 108.0, 106.7, 106.2, 82.0, 56.1,
56.0, 27.9.
HRMS (ESI): m/z [M + H]+ calcd for C21H23N2O4: 367.1652; found:
367.1649.
HRMS (ESI): m/z [M + H]+ calcd for C22H25N2O5: 397.1757; found:
tert-Butyl (1-Oxo-3-(o-tolyl)isoquinolin-2(1H)-yl)carbamate (2l)
397.1765.
White solid; yield: 74.2 mg (53%); mp 197.3–199.0 °C.
IR (KBr): 2921, 1746, 1656, 1623, 1484, 1358, 1249, 1162 cm–1
.
tert-Butyl (3-(4-Chlorophenyl)-1-oxoisoquinolin-2(1H)-yl)carba-
mate (2h)
1H NMR (500 MHz, CDCl3): δ = 8.40 (d, J = 8.0 Hz, 1 H), 7.64 (d, J = 6.0
Hz, 1 H), 7.50–7.46 (m, 3 H), 7.34–7.20 (m, 4 H), 6.42 (s, 1 H), 2.21 (s, 3
H), 1.29 (s, 9 H).
13C NMR (125 MHz, CDCl3): δ = 162.0, 155.0, 144.7, 136.7, 134.1,
132.9, 130.3, 129.9, 129.3, 128.9, 128.2, 126.5, 126.1, 125.9, 125.1,
106.7, 82.1, 27.8, 19.5.
White solid; yield: 100.8 mg (68%); mp 210.4–211.9 °C.
IR (KBr): 2970, 1752, 1643, 1617, 1491, 1368, 1245, 1149, 1090 cm–1
1H NMR (500 MHz, CDCl3): δ = 8.29 (d, J = 8.0 Hz, 1 H), 7.57 (t, J = 7.5
Hz, 1 H), 7.39 (dd, J = 18.5, 8.5 Hz, 4 H), 7.32 (dd, J = 18.0, 5.5 Hz, 3 H),
6.38 (s, 1 H), 1.30 (s, 9 H).
.
HRMS (ESI): m/z [M + H]+ calcd for C21H23N2O3: 351.1703; found:
351.1709.
13C NMR (125 MHz, CDCl3): δ = 161.9, 143.6, 136.4, 134.9, 133.1,
133.0, 130.4, 129.0, 128.1, 126.9, 126.2, 124.9, 112.2, 107.3, 82.4, 27.9.
HRMS (ESI): m/z [M + H]+ calcd for C20H20N2O3Cl: 371.1157; found:
tert-Butyl (1-Oxo-3-(m-tolyl)isoquinolin-2(1H)-yl)carbamate (2m)
371.1156.
White solid; yield: 54.6 mg (39%); mp 170.8–172.6 °C.
IR (KBr): 2981, 1749, 1653, 1617, 1477, 1368, 1249, 1152 cm–1
.
tert-Butyl (3-(4-Cyanophenyl)-1-oxoisoquinolin-2(1H)-yl)carba-
mate (2i)
1H NMR (500 MHz, CDCl3): δ = 8.40 (d, J = 8.0 Hz, 1 H), 7.65 (t, J = 7.5
Hz, 1 H), 7.50–7.45 (m, 2 H), 7.34–7.30 (m, 3 H), 7.24 (dd, J = 9.0, 5.5
Hz, 1 H), 7.11 (br s, 1 H), 6.48 (s, 1 H), 2.39 (s, 3 H), 1.42 (s, 9 H).
White solid; yield: 96.7 mg (67%); mp 186.7–188.4 °C.
IR (KBr): 2968, 1732, 1656, 1630, 1590, 1484, 1391, 1278, 1159, 1046
13C NMR (125 MHz, CDCl3): δ = 162.0, 155.4, 145.0, 137.6, 136.6,
134.5, 132.9, 129.7, 129.5, 129.0, 128.2, 127.8, 126.6, 126.1, 124.9,
107.1, 82.2, 27.9, 21.3.
HRMS (ESI): m/z [M + H]+ calcd for C21H23N2O3: 351.1703; found:
351.1701.
cm–1
.
1H NMR (500 MHz, CDCl3): δ = 8.31 (d, J = 8.0 Hz, 1 H), 7.62 (t, J = 7.5
Hz, 3 H), 7.58 (dd, J = 11.5, 4.5 Hz, 2 H), 7.45–7.41 (m, 2 H), 7.34 (br s,
1 H), 6.42 (s, 1 H), 1.30 (s, 9 H).
13C NMR (125 MHz, CDCl3): δ = 161.7, 155.4, 142.8, 138.9, 136.1,
133.3, 131.7, 129.8, 128.2, 127.3, 126.4, 125.1, 118.4, 112.6, 107.8,
82.7, 27.8.
N-(1-Oxo-3-phenylisoquinolin-2(1H)-yl)benzamide (2n)
White solid; yield: 89.7 mg (66%); mp 232.2–234.2 °C.
HRMS (ESI): m/z [M + H]+ calcd for C21H20N3O3: 362.1499; found:
362.1501.
IR (KBr): 2914, 1676, 1643, 1613, 1504, 1467, 1272, 1156, 1020 cm–1
.
1H NMR (500 MHz, CDCl3): δ = 9.67 (s, 1 H), 8.41 (d, J = 8.0 Hz, 1 H),
7.68 (t, J = 8.0 Hz, 1 H), 7.61–7.57 (m, 4 H), 7.54–7.48 (m, 2 H), 7.41–
7.35 (m, 4 H), 7.22 (t, J = 8.0 Hz, 2 H), 6.57 (s, 1 H).
13C NMR (125 MHz, CDCl3): δ = 166.5, 162.4, 144.8, 136.8, 134.1,
133.1, 131.9, 131.2, 129.0, 128.9, 128.2, 128.1, 128.0, 127.4, 126.7,
126.3, 124.8, 107.9.
tert-Butyl (3-(4-Methoxyphenyl)-1-oxoisoquinolin-2(1H)-yl)car-
bamate (2j)
White solid; yield: 87.8 mg (60%); mp 225.9–227.2 °C.
IR (KBr): 2961, 1742, 1643, 1603, 1511, 1361, 1252, 1146, 1033 cm–1
.
1H NMR (500 MHz, CDCl3): δ = 8.32 (d, J = 8.0 Hz, 1 H), 7.58 (t, J = 7.0
Hz, 1 H), 7.44–7.36 (m, 4 H), 7.01 (br s, 1 H), 6.86 (d, J = 8.5 Hz, 2 H),
6.40 (s, 1 H), 3.78 (s, 3 H), 1.35 (s, 9 H).
HRMS (ESI): m/z [M + H]+ calcd for C22H17N2O2: 341.1285; found:
341.1296.
13C NMR (125 MHz, CDCl3): δ = 162.1, 160.0, 155.4, 144.6, 136.7,
133.0, 130.4, 128.2, 127.0, 126.5, 126.1, 124.7, 113.4, 107.0, 82.3, 55.3,
28.0.
HRMS (ESI): m/z [M + H]+ calcd for C21H23N2O4: 367.1652; found:
367.1643.
4-Methyl-N-(1-oxo-3-phenylisoquinolin-2(1H)-yl)benzenesulfon-
amide (2o)
Yellow solid; yield: 74.9 mg (48%); mp 189.1–191.0 °C.
IR (KBr): 2934, 1670, 1593, 1431, 1156, 1090 cm–1
.
1H NMR (500 MHz, CDCl3): δ = 8.33 (s, 1 H), 8.16 (d, J = 8.0 Hz, 1 H),
7.68 (t, J = 7.5 Hz, 1 H), 7.53 (d, J = 7.5 Hz, 1 H), 7.46 (d, J = 7.5 Hz, 1 H),
7.47–7.41 (m, 2 H), 7.37–7.31 (m, 5 H), 7.02 (d, J = 8.0 Hz, 2 H), 6.49 (s,
1 H), 2.34 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 161.9, 144.4, 143.3, 136.3, 134.3,
134.1, 133.3, 129.3 (2 C), 128.5, 128.1, 128.0, 127.8, 126.9, 126.4,
124.2, 108.4, 21.5.
tert-Butyl (3-(2-Methoxyphenyl)-1-oxoisoquinolin-2(1H)-yl)car-
bamate (2k)
White solid; yield: 73.2 mg (50%); mp 197.1–199.0 °C.
IR (KBr): 2980, 1746, 1650, 1627, 1507, 1384, 1252, 1159, 1046 cm–1
.
1H NMR (500 MHz, CDCl3): δ = 8.34 (d, J = 8.0 Hz, 1 H), 7.54 (t, J = 7.5
Hz, 1 H), 7.41–7.30 (m, 5 H), 6.91 (t, J = 7.5 Hz, 1 H), 6.86 (d, J = 8.5 Hz,
1 H), 6.36 (s, 1 H), 3.72 (s, 3 H), 1.17 (s, 9 H).
13C NMR (125 MHz, CDCl3): δ = 161.9, 156.9, 154.4, 142.9, 136.8,
132.7, 131.1, 130.6, 128.2, 126.4, 126.1, 125.3, 123.7, 120.5, 110.3,
107.2, 81.6, 55.6, 27.8.
HRMS (ESI): m/z [M + H]+ calcd for C22H19N2O3S: 391.1111; found:
391.1121.
N-(1-Oxo-3-phenylisoquinolin-2(1H)-yl)benzenesulfonamide (2p)
White solid; yield: 63.1 mg (42%); mp 194.5–195.9 °C.
IR (KBr): 2940, 1673, 1557, 1442, 1341, 1152, 1090 cm–1
.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

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1H NMR (500 MHz, CDCl3): δ = 8.49 (br s, 1 H), 8.16 (d, J = 8.0 Hz, 1 H),
7.67 (t, J = 7.5 Hz, 1 H), 7.53 (d, J = 8.0 Hz, 1 H), 7.46–7.42 (m, 6 H),
7.32–7.29 (m, 3 H), 7.23–7.20 (m, 2 H), 6.52 (s, 1 H).
N-(6-Fluoro-1-oxoisoquinolin-2(1H)-yl)-4-methylbenzenesulfon-
amide (2u)
White solid; yield: 63.7 mg (48%); mp 244.5–245.5 °C.
13C NMR (125 MHz, CDCl3): δ = 161.8, 143.2, 137.2, 136.2, 134.0,
133.4, 129.3 (2 C), 128.7, 128.6, 128.1, 128.0, 127.9, 127.0, 126.4,
124.1, 108.4.
HRMS (ESI): m/z [M + H]+ calcd for C21H17N2O3S: 377.0955; found:
377.0973.
IR (KBr): 2981, 1650, 1610, 1560, 1461, 1272, 1166, 1093 cm–1
.
1H NMR (500 MHz, CDCl3): δ = 8.60 (s, 1 H), 8.05 (dd, J = 9.0, 5.5 Hz, 1
H), 7.57 (d, J = 8.0 Hz, 3 H), 7.19–7.10 (m, 4 H), 6.52 (d, J = 7.5 Hz, 1 H),
2.36 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 165.7 (d, JC–F = 251.2 Hz), 158.4, 153.1,
145.5, 138.8 (d, JC–F = 8.7 Hz), 132.5, 130.9 (d, JC–F = 10.0 Hz), 129.7,
128.5, 121.2, 115.95 (d, JC–F = 23.5 Hz), 111.5 (d, JC–F = 22.2 Hz), 105.6,
21.7.
N-(1-Oxo-3-phenylisoquinolin-2(1H)-yl)acetamide (2q)
White solid; yield: 15.6 mg (14%); mp 157.0–159.0 °C.
IR (KBr): 2930, 1696, 1610, 1487, 1411, 1375, 1265, 1116 cm–1
.
HRMS (ESI): m/z [M + H]+ calcd for C16H14N2O3SF: 333.0704; found:
1H NMR (500 MHz, CDCl3): δ = 8.12 (d, J = 8.0 Hz, 1 H), 7.62–7.60 (m, 1
H), 7.47 (d, J = 7.5 Hz, 1 H), 7.37–7.36 (m, 2 H), 7.30–7.25 (m, 5 H),
6.45 (s, 1 H), 2.28 (s, 3 H).
333.0705.
tert-Butyl (6-Fluoro-1-oxoisoquinolin-2(1H)-yl)carbamate (2v)
13C NMR (125 MHz, CDCl3): δ = 161.8, 144.5, 136.3, 134.1, 133.3,
White solid; yield: 60 mg (54%); mp 195.1–196.9 °C.
IR (KBr): 2936, 1739, 1650, 1613, 1481, 1278, 1149 cm–1
.
129.3, 128.5, 128.2, 128.0, 127.8, 126.9, 126.4, 124.2, 108.4, 21.5.
HRMS (ESI): m/z [M + H]+ calcd for C17H15N2O2: 279.1128; found:
279.1137.
1H NMR (500 MHz, CDCl3): δ = 8.41 (dd, J = 9.0, 5.5 Hz, 1 H), 7.57 (br s,
1 H), 7.24 (d, J = 7.5 Hz, 1 H), 7.18–7.15 (m, 2 H), 6.43 (d, J = 7.5 Hz, 1
H), 1.50 (s, 9 H).
tert-Butyl (1-Oxoisoquinolin-2(1H)-yl)carbamate (2r)
13C NMR (125 MHz, CDCl3): δ = 165.5 (d, JC–F = 250.0 Hz), 160.4, 155.6,
134.7, 131.3 (d, JC–F = 10.0 Hz), 129.0, 122.5, 115.6 (d, JC–F = 23.7 Hz),
111.2 (d, JC–F = 21.7 Hz), 105.0, 83.1, 28.0.
HRMS (ESI): m/z [M + H]+ calcd for C14H16N2O3F: 279.1140; found:
279.1150.
White solid; yield: 52 mg (50%); mp 196.6–197.5 °C.
IR (KBr): 2974, 1733, 1656, 1620, 1511, 1365, 1271, 1159, 1060 cm–1
1H NMR (500 MHz, CDCl3): δ = 8.41 (d, J = 8.0 Hz, 1 H), 7.78 (br s, 1 H),
7.67–7.64 (m, 1 H), 7.53–7.46 (m, 2 H), 7.21 (d, J = 7.5 Hz, 1 H), 6.49
(d, J = 7.5 Hz, 1 H), 1.48 (s, 9 H).
.
13C NMR (125 MHz, CDCl3): δ = 161.1, 155.7, 137.0, 133.4, 132.7,
128.0, 126.8, 126.1, 125.9, 105.7, 82.7, 28.0.
Acknowledgment
HRMS (ESI): m/z [M + H]+ calcd for C14H17N2O3: 261.1234; found:
261.1230.
We thank the National Natural Science Foundation of China (Nos.
21102104, 21502065) and the Natural Science Foundation of Zhejiang
Province (No. LY14B020011) for financial support.
4-Methyl-N-(1-oxoisoquinolin-2(1H)-yl)benzenesulfonamide (2s)
White solid; yield: 43.9 mg (35%); mp 239.4–241.4 °C.
IR (KBr): 2928, 1656, 1464, 1348, 1272, 1166, 1090 cm–1
Supporting Information
.
1H NMR (500 MHz, CDCl3): δ = 8.69 (s, 1 H), 7.97 (d, J = 8.0 Hz, 1 H),
7.58 (t, J = 8.0 Hz, 1 H), 7.50–7.46 (m, 4 H), 7.34 (t, J = 7.5 Hz, 1 H),
7.06 (d, J = 8.5 Hz, 2 H), 6.49 (d, J = 7.5 Hz, 1 H), 2.26 (s, 3 H).
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0035-1561947.
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13C NMR (125 MHz, CDCl3): δ = 159.1, 145.3, 136.4, 133.0, 132.6,
131.2, 129.6, 128.4, 127.6, 127.1, 126.4, 124.6, 106.3, 21.6.
References
HRMS (ESI): m/z [M + H]+ calcd for C16H15N2O3S: 315.0798; found:
315.0796.
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White solid; yield: 66.5 mg (63%); mp 216.1–218.0 °C.
IR (KBr): 2987, 1676, 1646, 1627, 1514, 1477, 1275 cm–1
1H NMR (500 MHz, CDCl3): δ = 10.47 (s, 1 H), 8.38 (d, J = 8.0 Hz, 1 H),
7.91 (d, J = 7.5 Hz, 2 H), 7.66 (t, J = 7.0 Hz, 1 H), 7.53 (d, J = 8.0 Hz, 1 H),
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265.0973.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

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Z.-L. Zhou et al.
Paper
Synthesis
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