Copper-catalyzed domino synthesis of isoquinolino[2,3-a]quinazolinones

Article abstract of DOI:10.1002/adsc.201100951

A copper-catalyzed domino method for synthesis of isoquinolino[2,3-a] quinazolinones has been developed using readily available, substituted methyl 2-(2-haloobenzamido)benzoates and nitriles as the starting materials. The domino process comprises an Ullmann-type C-arylation, intramolecular addition of NH with CN, and nucleophilic attack of amino to ester group. The inexpensive, convenient and efficient copper-catalyzed method should provide a new and useful strategy for constructing nitrogen heterocycles. Copyright

Full text of DOI:10.1002/adsc.201100951

FULL PAPERS
DOI: 10.1002/adsc.201100951
Copper-Catalyzed Domino Synthesis of
Isoquinolino[2,3-a]quinazolinones
AHCTUNGTRENNUNG
Tao Liu,a Chongyu Zhu,a Haijun Yang,a and Hua Fua,*
a
Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of
Chemistry, Tsinghua University, Beijing 100084, Peopleꢀs Republic of China
Fax : (+ 86)-10-6278-1695; e-mail: fuhua@mail.tsinghua.edu.cn
Received: December 5, 2011; Revised: February 8, 2012; Published online: May 15, 2012
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201100951.
Abstract: A copper-catalyzed domino method for and efficient copper-catalyzed method should pro-
synthesis of isoquinolinoACTHUNTGRNEUNG[2,3-a]quinazolinones has vide a new and useful strategy for constructing nitro-
been developed using readily available, substituted gen heterocycles.
methyl 2-(2-haloobenzamido)benzoates and nitriles
as the starting materials. The domino process com-
prises an Ullmann-type C-arylation, intramolecular Keywords: copper; domino method; isoquinolino-
addition of NH with CN, and nucleophilic attack of
ACHTUNGTREN[NGNU 2,3-a]quinazolinones; nitrogen heterocycles; Ull-
amino to ester group. The inexpensive, convenient mann-type coupling
Introduction
bacterial, antifungal, antiviral, antimycobacterial and
antimalarial substances.[6] In addition, they are inhibi-
Isoquinolinone derivatives widely occur in natural tors of various enzymes including monoamine ox-
products,[1], and they are also versatile building blocks idase, aldose reductase, tumor necrosis factor a, thy-
for the total synthesis of natural alkaloids.[2] Some iso- midylate synthase.[6,7] However, investigations on the
quinolinones exhibit various biological and medicinal hybrid structure of isoquinoline and quinazoline
activities such as antihypertensive activity[3a,b] and act motifs, namely isoquinolino
ACTHNUTRGNE[UNG 2,3-a]quinazolinone de-
as NK3 antagonists,[3c] melatonin MT1 and MT2 recep- rivatives (Figure 1), are very rare, and only two refer-
tor agonists,[3d] Rho-kinase inhibitors,[3e] and JNK in- ences were found by Scifinder search in which there
hibitors.[3f] They also are novel orally active 5-HT3 are limited and special compounds.[8] Therefore, the
antagonists,[4a] thymidylate synthase (TS) inhibitors,[4b] development of a convenient and efficient approach
or find use for the treatment of stomach tumors and to isoquinolinoACTHNUTRGNEU[GN 2,3-a]quinazolinone derivatives will be
diseases of human brain cells.[1b] Quinazolinone deriv- valuable for the screening of novel biologically active
atives found in natural products show various biologi- molecules. Recently, there has been great progress in
cal and pharmacological activities.[5] For example, copper-catalyzed Ullmann-type couplings,[9] and some
they act as psychotropic, hypnotic, cardiotonic and an- nitrogen heterocycles were made through such cou-
tihistamine agents, and exhibit many central nervous plings by other groups[10] and by us[11] Herein, we
system effects as well as cardiovascular and anti-in- report an efficient copper-catalyzed synthesis of
flammatory activity.[5] They are used as potent anti- isoquinolino
ACTHNUGRTENUNG[2,3-a]quinazolinone derivatives through
domino reactions of substituted methyl 2-(2-bromo-
benzamido)benzoate with nitriles under mild condi-
tions.
Results and Discussion
At first, methyl 2-(2-bromobenzamido)benzoate (1a)
and ethyl 2-cyanoacetate (2b) were used as the model
substrates to optimize the reaction conditions includ-
Figure 1. IsoquinolinoACHTUNTGRNEUNG[2,3-a]quinazolinone as hybrid struc-
ture of isoquinoline and quinazolinone motifs.
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Table 1. Copper-catalyzed domino reaction of methyl 2-(2-bromobenzamido)benzoate (1a) with ethyl 2-cyanoacetate (2b) or
2-phenylacetonitrile (2d) leading to isoquinolino
[2,3-a]quinazolinone 3b or 3d: optimization of reaction conditions.[a]
AHCTUNGTRENNUNG
Entry
R3
Catalyst
Base
Solvent
Temperature [8C]
Yield [%][b]
1
2
3
4
5
6
7
8
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
Ph
CuI
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Cs2CO3
K3PO4
Na2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMSO
dioxane
toluene
DMF
DMF
DMF
DMF
DMF
DMF
DMF
100
100
100
100
100
100
100
100
100
100
100
100
110
90
75
52
72
42
30
37
69
61
38
44
51
trace
71
CuCl
CuBr
Cu2O
CuBr2
Cu
N
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
CuI
9
10
11
12
13
14
15
16
17
18
19
63
43
100
100
100
100
100
Ph
Ph
H
n-C3H7
52
71[c]
0[c]
0[c]
[a]
Reaction conditions: methyl 2-(2-bromobenzamido)benzoate (1a) (0.5 mmol), ethyl 2-cyanoacetate (2b) or 2-phenylaceto-
nitrile (2d) (0.6 mmol), catalyst (0.05 mmol), base (0.75 mmol), solvent (1 mL) under a nitrogen atmosphere.
Isolated yield.
[b]
[c]
In the presence of l-proline (0.1 mmol).
ing catalysts, ligands, bases, solvents and reaction tem- K2CO3 as the base (relative to amount of 1), and
peratures under a nitrogen atmosphere. As shown in DMF as the solvent at 1008C for alkyl 2-cyanoace-
Table 1, six copper salts were screened in DMF in the tates or use of 10 mol% of CuI as the catalyst,
presence of 0.1 equiv. of CuI and 1.5 equiv. of K2CO3 20 mol% l-proline as the ligand, 1.5 equiv. of Cs2CO3
(relative to amount of 1a) at 1008C (entries 1–6), and as the base (relative to amount of 1), and DMF as the
CuI provided the highest yield (entry 1). We tested solvent at 1008C for other nitriles.
various bases (compare entries 1, 7–9), and K2CO3
We investigated the scope of the copper-catalyzed
showed the best result (entry 1). The effect of solvents domino reactions of substituted methyl 2-(2-haloben-
was also investigated (compare entries 1, 10–12), and zamido)benzoates (1) with nitriles (2) under the opti-
DMF was suitable (entry 1). We attempted different mized conditions. As shown in Table 2, the corre-
temperatures (compare entries 1, 13 and 14), and sponding isoquinolinoACTHUNTGRNEUNG[2,3-a]quinazolinones (3) were
1008C was optimal (entry 1). When 2-phenylacetoni- obtained in moderate to good yields for various ex-
trile (2d) was used the partner of 1a, only 43% yield amined substrates at 1008C. For substituted methyl 2-
was afforded (entry 15). The yield rose to 52% when (2-halobenzamido)benzoates, the aryl bromides ex-
Cs2CO3 replaced K2CO3 as the base (entry 16). The hibited higher reactivity than the corresponding chlor-
reaction provided a 71% yield in the presence of l- ides, only aryl chloride containing a nitro group could
proline (entry 17). When acetonitrile (entry 18) or bu- work. For nitriles (2), alkyl 2-cyanoacetates (2a–c)
tyronitrile (entry 19) was used as the substrate, no re- showed higher reactivity than substituted 2-phenyla-
action was observed. Therefore, the optimized condi- cetonitriles and 3-oxo-3-phenylpropanenitrile (2d–g),
tions for reactions of substituted methyl 2-(2-haloben- and a ligand (l-proline) and a stronger base (Cs2CO3)
zamido)benzoates (1) with nitriles (2) are as follows: were required for 2d–g. The copper-catalyzed domino
use of 10 mol% of CuI as the catalyst, 1.5 equiv. of synthesis of isoquinolinoACHTNUGTRNEUNG[2,3-a]quinazolines showed
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Copper-Catalyzed Domino Synthesis of Isoquinolino
ACHTUNGTRENNUNG
Table 2. Copper-catalyzed domino synthesis of isoquinolinoACHTUNGTRENNUNG
Entry
1
1
2
Reaction time
12 h
3
Yield [%]
77
1a
1a
2a
2b
3a
3b
2
12 h
75
3
4
5
1a
1a
1a
2c
2d
2e
12 h
12 h
12 h
3c
3d
3e
82
71
62
6
7
8
9
1a
1b
1c
1d
2f
2c
2c
2b
12 h
12 h
12 h
12 h
3f
3g
3h
3i
78
54
65
69
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Tao Liu et al.
FULL PAPERS
Table 2. (Continued)
Entry
1
2
Reaction time
12 h
3
Yield [%]
64
10
1e
1f
2c
3j
11
12
2b
12 h
12 h
3k
62
59
1g
2e
3l
13
14
15
16
1h
1h
1h
1h
2b
2c
2d
2g
18 h
18 h
18 h
18 h
3m
3n
3o
3p
61
61
55
68
17
1i
2c
2c
18 h
18 h
3q
3r
52
57
18
1f
[a]
Reaction conditions: 1 (0.5 mmol), 2 (0.6 mmol), CuI (0.05 mmol), K2CO3 (0.75 mmol), Cs2CO3 (0.75 mmol), DMF
(1 mL) under a nitrogen atmosphere. K2CO3 as the base and no addition of ligand for substrates 2a–c; Cs2CO3 as the
base and l-proline as the ligand for substrates 2d–g.
[b]
Isolated yield.
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Copper-Catalyzed Domino Synthesis of IsoquinolinoACTHNUTRGNE[NUG 2,3-a]quinazolinones
Scheme 1. Possible mechanism for copper-catalyzed synthesis of isoquinolinoACTHNUTRGNEU[GN 2,3-a]quinazolinones.
good tolerance of the functional groups in the sub-
strates including esters (entries 1–3, 7–14, 17 and 18),
ethers (7, 12 and 17), amides (entries 1–18), C F
(2) (0.6 mmol), K2CO3 (0.75 mmol, 104 mg) (without ligand)
for substrates 2a-c or Cs2CO3 (0.75 mmol, 245 mg) and l-
proline (0.01 mmol, 12 mg) for substrates 2d–g. The tube
was evacuated twice and backfilled with nitrogen, and DMF
(1 mL) was added to the tube under a nitrogen atmosphere.
The tube was sealed and then the mixture was allowed to
stir under a nitrogen atmosphere at 1008C for 12 or 18 h.
After completion of the reaction, the resulting solution was
cooled to room temperature, and the solvent was removed
with the aid of a rotary evaporator. The residue was purified
by column chromatography on silica gel using chloroform/
methyl alcohol (10:1) as eluent to provide the desired prod-
uct (3). Three representative examples are shown as fol-
lows:
À
À
À
bond (entry 6), C Cl bond (entry 12), C Br bond
(entry 18) and nitro group (entries 13–18).
A possible mechanism for the copper-catalyzed
domino synthesis of isoquinolinoACHTUNTRGNEUNG[2,3-a]quinazolinones
(3) is suggested in Scheme 1. The Hurtley-type cou-
pling12 (C-arylation of a-C H in nitrile) of substituted
À
methyl 2-(2-halobenzamido)benzoates (1) with nitriles
(2) first provides I, and then intramolecular addition
of NH with CN in I leads to II. Isomerization of the
C=NH double bond forms III, and intramolecular nu-
cleophilic attack of NH2 to the ester group yields the
target product 3.
Methyl
6,12-dihydro-5,12-dioxo-5H-isoquinolinoACHTUNGTRENNUNG[2,3-a]-
quinazoline-7-carboxylate (3a): Eluent: chloroform/methyl
alcohol (10:1); yield: 123 mg (77%); yellow solid; mp 195–
1978C. 1H NMR (DMSO-d6, 300 MHz): d=8.60 (s, 1H),
8.07–8.16 (m, 3H), 7.67–7.78 (m, 2H), 7.37–7.53 (m, 2H),
3.90 (s, 3H); 13C NMR (DMSO-d6, 75 MHz): d=169.1,
161.8, 158.0, 146.1, 137.9, 134.4, 134.3, 133.9, 128.6, 127.6,
127.0, 125.7, 125.7, 122.7, 122.4, 119.7, 86.9, 53.0; HR-MS
(ESI): m/z=321.0877, calcd. for C18H13N2O4 [M+H]+:
321.0875.
Conclusions
We have developed a simple and efficient copper-cat-
alyzed domino method for the synthesis of
isoquinolinoACHTUNGTRENNUNG[2,3-a]quinazolinones. The protocol uses
cheap and readily available CuI as the catalyst and
substituted methyl 2-(2-halobenzamido)benzoates and
nitriles as the starting materials, and the correspond-
7-Phenyl-6H-isoquinolinoACHTNUTRGNE[NUG 2,3-a]quinazoline-5,12-dione
(3d): Eluent: chloroform/methyl alcohol (10:1); yield:
120 mg (71%); yellow solid; mp 243–2458C. 1H NMR
(DMSO-d6, 300 MHz): d=9.41 (s, 1H), 9.05 (d, J=4.5 Hz,
1H), 8.32 (d, J=3.9 Hz, 1H), 8.08 (d, J=4.6 Hz, 1H), 7.78
(m, 1H), 7.37–7.60 (m, 8H), 6.90 (m, 1H); 13C NMR
(DMSO-d6, 75 MHz): d=162.2, 157.9, 138.4, 137.2, 133.9,
133.9, 133.8, 133.0, 132.3, 130.3, 129.1, 128.6, 127.6, 127.0,
125.4, 124.1, 122.6, 121.8, 119.6, 100.5; HR-MS (ESI) m/z=
361.0955, calcd. for C22H14N2NaO2 [M+Na]+: 361.0953.
ing isoquinolinoACHTUNGTRENNUNG[2,3-a]quinazolinones were obtained
in moderate to good yields under mild conditions.
The inexpensive, convenient and efficient copper-cat-
alyzed method should provide a new and useful strat-
egy for the construction of nitrogen-containing het-
erocycles.
Butyl
5H-isoquinolinoAHCTUNGTRENNUNG
10-chloro-6,12-dihydro-2,3-dimethoxy-5,12-dioxo-
[2,3-a]quinazoline-7-carboxylate (3l):
Eluent: chloroform/methyl alcohol (6:1); yield: 135 mg
(59%); yellow solid; mp 197–1998C. 1H NMR (DMSO-d6,
300 MHz): d=8.37 (m, 1H), 8.29 (m, 1H), 8.14 (m, 1H),
7.74 (m, 1H), 7.45 (m, 1H), 4.36 (m, 2H), 3.87 (b, 6H), 1.73
(m, 2H), 1.41 (m, 2H), 0.91 (t, J=7.2 Hz, 3H); 13C NMR
(DMSO-d6, 75 MHz): d=168.5, 160.8, 157.3, 153.5, 148.7,
145.6, 133.9, 132.7, 132.5, 129.9, 128.1, 128.0, 127.7, 123.5,
112.9, 107.9, 106.5, 86.4, 66.0, 56.6, 30.6, 19.4, 14.0; HRMS
(ESI) m/z=479.0989, calcd. for C23H21ClN2NaO6 [M+Na]+:
479.0986.
Experimental Section
General Procedure for Domino Reactions of Sub-
stituted 2-Halobenzamides with Nitriles leading to
IsoquinolinoACHTUNGTRENNUNG[2,3-a]quinazolinones
A 25-mL Schlenk tube equipped with a magnetic stirring
bar was charged with CuI (0.05 mmol, 9 mg), substituted
methyl 2-(2-halobenzamido)benzoate (1) (0.5 mmol), nitrile
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The authors wish to thank the National Natural Science
Foundation of China (Grant Nos. 20972083, 21172128 and
21105054), and the Ministry of Science and Technology of
China (Grant No. 2012CB722605) for financial support.
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