Recyclable Heterogeneous Palladium-Catalyzed Carbonylative Cyclization of 2-Iodoanilines with Aryl Iodides Leading to 2-Arylbenzoxazinones

Article abstract of DOI:10.1055/s-0039-1690265

A highly efficient and practical heterogeneous palladium-catalyzed carbonylative coupling of 2-iodoanilines with aryl iodides has been developed. The reaction occurs smoothly in toluene at 110 °C with N, N -diisopropylethylamine as base under carbon monoxide (5 bar) and offers a general and powerful tool for the construction of various valuable 2-arylbenzoxazinones with excellent atom-economy, high functional group tolerance, good to high yields, and easy recyclability of the palladium catalyst. The reaction is the first example of heterogeneous palladium-catalyzed carbonylative coupling for the preparation of diverse 2-arylbenzoxazinones from commercially easily available 2-iodoanilines and aryl iodides.

Full text of DOI:10.1055/s-0039-1690265

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2019, 51, A–J
paper
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Z. Xu et al.
Paper
Synthesis
Recyclable Heterogeneous Palladium-Catalyzed Carbonylative
Cyclization of 2-Iodoanilines with Aryl Iodides Leading to 2-Aryl-
benzoxazinones
Zhaotao Xu
Bin Huang
O
2P-MCM-41-Pd(OAc)2
(5 mol%)
I
I
O
Zebiao Zhou
Mingzhong Cai*
R
+
CO
+
R1
R
0
0
0
0-0
0
0
2-1
0
5
6-2
8
4
6
N
R1
DiPEA, toluene, 110 °C
NH2
(5 bar)
Key Laboratory of Functional Small Organic Molecules, Ministry
of Education and College of Chemistry & Chemical Engineering,
Jiangxi Normal University, Nanchang 330022, P. R. of China
mzcai@jxnu.edu.cn
Broad substrate scope
Good to excellent yields
Excellent atom economy
High FG compatibility
37 examples
up to 92% yield
Recyclable palladium catalyst
Received: 01.09.2019
Accepted after revision: 22.10.2019
Published online: 13.11.2019
of 2-iodobenzoic acids with arylmethanamines,9 oxidation
of 2-arylindoles,10 and aza-Wittig reaction of 2-azidophenyl
anhydrides11 and palladium-catalyzed carbon–carbon tri-
ple-bond cleavage of 2-azidoalkynylbenzenes,12 as well as
CoCl2- or Ag2O-mediated intramolecular oxidative cycliza-
tion.13 In addition, transition-metal-free syntheses of ben-
zoxazinones have also been reported via oxidation of 2-
arylindoles with oxone and oxidative cyclization of 2-ami-
nobenzoic acids with aryl aldehydes or 2-aminobenzyl al-
cohols with aldehydes.14 However, in terms of the availabil-
ity and scope of substrates, yields, and required reaction
conditions, most of these methods suffer from one or more
drawbacks.
DOI: 10.1055/s-0039-1690265; Art ID: ss-2019-h0498-op
Abstract A highly efficient and practical heterogeneous palladium-
catalyzed carbonylative coupling of 2-iodoanilines with aryl iodides has
been developed. The reaction occurs smoothly in toluene at 110 °C
with N,N-diisopropylethylamine as base under carbon monoxide (5 bar)
and offers a general and powerful tool for the construction of various
valuable 2-arylbenzoxazinones with excellent atom-economy, high
functional group tolerance, good to high yields, and easy recyclability of
the palladium catalyst. The reaction is the first example of heteroge-
neous palladium-catalyzed carbonylative coupling for the preparation
of diverse 2-arylbenzoxazinones from commercially easily available 2-
iodoanilines and aryl iodides.
Palladium-catalyzed carbonylative reactions of com-
mercially readily available aryl halides with inexpensive
carbon monoxide have become a general and practical
route for the synthesis of benzoic acid derivatives.15 The
combination of such carbonylation reactions with subse-
quent intramolecular cyclization processes would allow for
a highly efficient construction of various heterocycles.16
Palladium-catalyzed carbonylative cyclization reactions
have been developed into a highly efficient and powerful
tool for the synthesis of benzoxazinones.17 Cacchi et al. de-
scribed a general approach for the synthesis of benzoxazi-
nones via the carbonylative coupling of 2-iodoanilines with
unsaturated halides or triflates.17a Similar carbonylative
coupling reactions of 2-iodoanilines with acid chlorides
were reported by the Alper group17b and the Petricci
group.17c Wu and Beller have developed palladium-cata-
lyzed carbonylative cyclization reactions of 2-bromoani-
lines with aryl bromides,17d acid anhydrides,17e or isocya-
nates.17f Palladium-catalyzed carbonylative C–H activation
of benzanilides or aryl urea derivatives for the synthesis of
benzoxazinones was independently reported by the Yu
group17g and the Lloyd-Jones and Booker-Milburn group.17h
In addition, Pd-catalyzed carbonylative cyclization of
Key words palladium, benzoxazinone, carbonylative coupling, 2-iodo-
aniline, heterogeneous catalysis
Benzoxazinones make up a class of important fused N-
heterocycles that are present in numerous biological com-
pounds and pharmaceutical drugs1 and exhibit a variety of
biological activities such as antibacterial, antifungal, HSV-1
protease inhibition, serine protease inhibition, and other
activities.2 They are also versatile and valuable synthetic in-
termediates in organic synthesis and medicinal chemis-
try.1a,3 For instance, 2-aryl-substituted 4H-benzoxazin-4-
ones have been employed as key building blocks in the syn-
thesis of bioactive quinazolin-4(3H)-one derivatives.4 As a
result, various methods have been developed for the con-
struction of these compounds over the past decades.5 The
most common approaches for the synthesis of benzoxazi-
nones are the cyclization of anthranilic acid, N-acylanthra-
nilic acid, and isotoic anhydride.6 Recently, transition-
metal-mediated reactions have been developed for the con-
struction of benzoxazinones; these include copper-cata-
lyzed cyclization of N-acyl-2-iodobenzamides,7 oxidative
cyclization of N-TFA-protected 2-alkynylanilines,8 reaction
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–J
Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
Z. Xu et al.
Paper
Synthesis
N-acyl-2-haloanilines in the presence of CO surrogates such
as paraformaldehyde, phenyl formate, and oxalyl chloride
has also been developed for the construction of benzoxazi-
nones.18
in high yield by the reaction of (EtO)3Si(CH2)3NH2 with
paraformaldehyde and HPPh2.23 Condensation of meso-
porous MCM-41 with (EtO)3Si(CH2)3N(CH2PPh2)2 at 110 °C
in toluene, followed by treatment with Me3SiCl at room
temperature gave an MCM-41-anchored bidentate phos-
phine ligand (2P-MCM-41). Subsequent reaction of 2P-
MCM-41 with Pd(OAc)2 in acetone at 60 °C for 3 days af-
forded the bidentate phosphino-modified MCM-41-an-
chored palladium complex [2P-MCM-41-Pd(OAc)2] as a
light yellow powder, with a palladium content of 0.37
mmol/g based on ICP-AES analysis. The TEM images of fresh
2P-MCM-41-Pd(OAc)2 complex (a) and the recovered palla-
dium catalyst (b) after recycling 8 times are shown in Figure
1. The highly ordered structures with a hexagonal ordered
porous parallel channels can be clearly observed from this
figure. In addition, from Figure 1b, one can easily observe
the palladium nanoparticles as black dots either inside the
pore of the mesoporous MCM-41 or impregnated on the ex-
ternal surface of the support, indicating that the oxidation
state of palladium in the used catalyst is Pd(0).
Although these palladium-catalyzed carbonylative cy-
clizations are highly efficient for the synthesis of benzoxaz-
inones,17,18 application of these homogeneous palladium
complexes in large-scale synthesis or industry remains a
challenge, because expensive palladium catalysts are diffi-
cult to recover from reaction mixtures and cannot be recy-
cled. Moreover, homogeneous palladium catalysis might
lead to unacceptable palladium contamination of the de-
sired product owing to coordination of benzoxazinone mol-
ecules to palladium and palladium leaching, thereby re-
stricting its application to the construction of some drug
molecules containing benzoxazinones, which have to be
free metal residues. Catalyst recycling represents one of the
most important features in green organic synthesis. In re-
cent years, some heterogeneous palladium-catalyzed car-
bonylation reactions have been reported with silica-sup-
ported palladium complexes or Pd/C as catalysts.19 To over-
come these drawbacks, our ongoing interest in developing
green and sustainable catalytic systems for organic trans-
formations20 has led us to investigate a highly efficient het-
erogeneous palladium-catalyzed double carbonylation pro-
cedure, which allows for a general construction of 2-aryl-
benzoxazinones starting from commercially easily available
2-iodoanilines and aryl iodides (Scheme 1). To the best of
our knowledge, this method is the first example of a hetero-
geneous Pd-catalyzed carbonylative cyclization reaction for
the synthesis of benzoxazinone derivatives.
toluene
(EtO)3Si(CH2)3NH2
+
(CH2O)n + HPPh2
60 °C, 12 h
1. MCM-41
toluene, 110 °C, 24 h
PPh2
PPh2
(EtO)3Si(CH2)3N
2. Me3SiCl, toluene
rt, 24 h
OSiMe3
PPh2
O
Pd(OAc)2
Si
N
O
acetone
60 °C, 3 d
PPh2
OEt
2P-MCM-41
OSiMe3
PPh2
O
Si
Pd(OAc)2
PPh2
N
O
O
OEt
I
2P-MCM-41-Pd(OAc)2
(5 mol%)
2P-MCM-41-Pd(OAc)2
O
R
R
CO
Ar-I
+
+
DiPEA, toluene, 110 °C
Scheme 2 Preparation of the 2P-MCM-41-Pd(OAc)2 complex
NH2
N
Ar
(5 bar)
1
2
3
OSiMe3
PPh2
O
O
Si
Pd(OAc)2
N
PPh2
OEt
2P-MCM-41-Pd(OAc)2
Scheme 1 Heterogeneous palladium-catalyzed carbonylative coupling
of 2-iodoanilines with aryl iodides
Mesoporous MCM-41 has emerged as an ideal support
for immobilization of homogeneous catalysts, because of its
unique properties such as extremely high surface area, ho-
mogeneity of the pores, big pore volume, and high thermal
stability in comparison with other solid supports.21 In addi-
tion, nano-sized catalysts can serve as efficient bridges and
fill the gap between homogeneous and heterogeneous cata-
lysts.22 The bidentate phosphino-modified MCM-41-an-
chored palladium complex [2P-MCM-41-Pd(OAc)2] was
readily prepared according to our previously reported pro-
cedure, as illustrated in Scheme 2.20h Firstly, the triethoxy-
silyl-containing bidentate phosphine ligand was obtained
Figure 1 TEM images of fresh 2P-MCM-41-Pd(OAc)2 complex (a) and
the recovered palladium catalyst (b) after recycling 8 times
The 2P-MCM-41-Pd(OAc)2 complex was then employed
as the catalyst for the carbonylative coupling of 2-iodoani-
lines with aryl iodides. Initial experiments, with 2-iodoani-
line (1a) and iodobenzene (2a) under carbon monoxide (5
bar), were performed to optimize the reaction conditions
(solvent, base, catalyst loading, reaction temperature), and
the results are listed in Table 1. At first, the solvent effect on
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–J

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Z. Xu et al.
Paper
Synthesis
the model reaction was examined in the presence of 2P-
MCM-41-Pd(OAc)2 (5 mol%) with K2CO3 as base at 110 °C,
and a significant solvent effect was observed (entries 1–7).
When NMP and toluene were used as solvents, the desired
3a was isolated in good yields, with toluene giving the best
result (entry 5), while other solvents such as DMF, DMA,
DMSO, MeCN, and dioxane were substantially less effective
and considerable amounts of non-cyclized intermediate [N-
benzoyl-2-iodoaniline] were detected as a byproduct. Our
next studies focused on the effect of base on the model re-
action with toluene as solvent (entries 8–11). Replacement
of K2CO3 with organic bases such as NEt3, DBU, DiPEA, and
TMEDA provided the target product 3a in 80–88% yield,
with DiPEA found to be the most efficient (entry 10). Re-
ducing reaction temperature to 100 °C resulted in a de-
creased yield and a significant amount of non-cyclized in-
termediate was observed (entry 12), while raising reaction
temperature to 120 °C did not increase the yield of 3a (en-
try 13). Lower catalyst loading (2.5 mol%) also led to a sig-
nificant decrease in the yield, and a mixture of starting ma-
terials, non-cyclized intermediate, and 3a was obtained
(entry 14); however, increasing the loading of the catalyst
to 10 mol% did not enhance the yield significantly (entry
15). When Pd(OAc)2 (5 mol%) and PPh3 (10 mol%) were used
as the catalyst system, the desired product 3a was isolated
in only 80% yield (entry 16), indicating that the catalytic ef-
ficiency of 2P-MCM-41-Pd(OAc)2 was higher than that of
the homogeneous Pd(OAc)2/2PPh3 system. Thus, the opti-
mized reaction conditions for this carbonylative coupling
are the use of 2P-MCM-41-Pd(OAc)2 (5 mol%), DiPEA (4
equiv) as base, in toluene as solvent, at 110 °C, and under
CO (5 bar) for 24 hours (entry 10).
Table 1 Optimization of the Reaction Conditionsa
O
I
I
O
2P-MCM-41-Pd(OAc)2
+
CO (5 bar), solvent
base, temp
NH2
N
1a
2a
3a
Entry
Solvent
Base
Temp
(°C)
Pd loading Yield
(mol%)
(%)b
1
2
NMP
K2CO3
110
110
110
110
110
110
110
110
110
110
110
100
120
110
110
110
5
5
70
61
52
58
77
46
39
80
82
88
83
69
87
53
89
80
DMF
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
NEt3
3
DMA
5
4
DMSO
toluene
MeCN
5
5
5
6
5
7
dioxane
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
5
8
5
9
DBU
5
10
11
12
13
14
15
16c
DiPEA
TMEDA
DiPEA
DiPEA
DiPEA
DiPEA
DiPEA
5
5
5
5
2.5
10
5
a Reaction conditions: 1a (1.2 mmol), 2a (1.0 mmol), base (4.0 mmol), sol-
vent (2 mL), CO (5 bar), 24 h.
b Isolated yield.
c Pd(OAc)2 (5 mol%) and PPh3 (10 mol%) were used.
With this promising result in hand, we started to exam-
ine the substrate scope of this heterogeneous palladium-
catalyzed carbonylative coupling reaction under the opti-
mal reaction conditions. Firstly, the substrate scope of aryl
iodides was investigated by evaluating a variety of aryl io-
dides 2; the results are summarized in Table 2. Iodoben-
zenes 2b–d bearing various para or meta electron-donating
substituents undergo the carbonylative cyclization with 2-
iodoaniline 1a smoothly to give the corresponding products
3b–d in good to excellent yields. Electron-deficient aryl io-
dides 2e–k showed similar reactivity with iodobenzene 2a
and afforded the desired 2-arylbenzoxazinones 3e–k in 78–
92% yield. Notably, 4-bromoiodobenzene (2g) underwent
the carbonylative coupling selectively to give the corre-
sponding 2-(4-bromophenyl)-4H-benzo[d][1,3]oxazin-4-
one (3g) in 88% yield. However, aryl iodides bearing a
strong electron-withdrawing group such as 4-cyanoiodo-
benzene (2l) and 4-nitroiodobenzene (2m) afforded the
corresponding 2-arylbenzoxazinones 3l and 3m in lower
yields, due to the formation of byproducts. Sterically hin-
dered ortho-substituted iodobenzenes 2n–p were also com-
patible with the standard conditions and produced the de-
sired products 3n–p in good yields. Additionally, bulky 1-
iodonaphthalene (2q) proved to be also a good substrate
and provided the target product 3q in 83% yield. In addition
to substituted iodobenzenes, heteroaryl iodides such as 3-
iodothiophene (2r) and 2-iodothiophene (2s) reacted well
in this transformation and furnished the expected 2-het-
eroarylbenzoxazinones 3r and 3s in high yields. A wide
range of electron-donating or electron-withdrawing func-
tional groups such as methyl, methoxy, fluoro, chloro, bro-
mo, ketone, ester, cyano, and trifluoromethyl, as well as
bulky 1-naphthyl or heteroaryl groups were tolerated well.
Encouraged by the above results, we then examined the
substrate scope of 2-iodoanilines 1 under the optimized re-
action conditions; the results are listed in Table 3. To our
delight, we found this transformation to be quite general for
a wide range of substituted 2-iodoanilines. For example, 2-
iodo-4-methylaniline (1b) underwent the carbonylative
coupling reaction smoothly with a variety of electron-neu-
tral, electron-rich, or electron-poor aryl iodides to afford
the corresponding 2-arylbenzoxazinones 3t–w in 82–87%
yield. The reactions of 2-iodo-4-methylaniline (1b) with
bulky 1-iodonaphthalene (2q) or 3-iodothiophene (2r) also
worked well, thus providing the desired products 3x and 3y
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–J

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Synthesis
Table 2 Heterogeneous Palladium-Catalyzed Carbonylative Coupling
bonylative coupling reaction of 2-bromoanilines with aryl
bromides, but, unfortunately, no desired products were de-
tected even at higher reaction temperatures and under
higher pressures of CO. This is because the oxidative addi-
tion reaction of an aryl bromide to the heterogeneous phos-
phine–palladium(0) complex is too slow under the opti-
mized conditions, and, thus, 2-arylbenzoxazinones 3g and
3g′–j′ were obtained in high yields through the chemoselec-
tive carbonylative couplings of 4-bromoiodobenzene (2g)
with 2-iodoaniline (1a) and 5- or 4-bromo-substituted 2-
iodoanilines 1g or 1h with aryl iodides, respectively. The
present method is applicable to a wide range of aryl iodides
and various 2-iodoanilines and provides a novel, highly effi-
cient, and practical procedure for the construction of 2-ar-
ylbenzoxazinones from easily available starting materials.
of 2-Iodoaniline with Various Aryl Iodidesa
O
I
2P-MCM-41-Pd(OAc)2
(5 mol%)
I
O
+
CO
+
(5 bar)
NH2
DiPEA, toluene, 110 °C
N
R
1a
2
R
3a–s
O
O
N
O
O
O
O
N
N
3a, 88%
3c, 84%
3b, 90%
OMe
Me
O
O
O
O
O
O
O
Me
N
N
N
3d, 78%
3e, 87%
3f, 92%
Cl
CF3
CN
F
O
O
O
Table 3 Heterogeneous Palladium-Catalyzed Carbonylative Coupling
of Various Substituted 2-Iodoanilines with Aryl Iodidesa
O
O
Cl
Cl
N
N
3h, 83%
N
O
3g, 88%
Br
3i, 78%
O
O
I
O
O
I
2P-MCM-41-Pd(OAc)2
(5 mol%)
R
R1
O
+ CO +
(5 bar)
R
O
O
N
R1
DiPEA, toluene, 110 °C
NH2
N
3
N
N
2
1
O
3j, 85%
3l, 46%
3k, 84%
CO2Me
Me
O
O
O
O
O
N
O
Me
Me
Me
O
O
O
O
O
O
Cl
OMe
N
N
N
N
N
3v, 82%
3u, 87%
3t, 83%
Me
Cl
3m, 40%
NO2
3n, 75%
3o, 78%
O
O
N
O
N
O
O
O
Me
Me
Me
O
O
O
F
O
O
O
N
N
S
N
3q, 83%
3x, 79%
3y, 84%
3w, 83%
N
CO2Me
S
3p, 79%
O
O
O
F
3r, 86%
O
F
O
O
O
O
N
3a', 80%
N
3b', 77%
O
N
3z, 75%
F
F
N
OMe
3s, 87%
O
S
O
a Reaction conditions: 1a (1.2 mmol), 2 (1.0 mmol), DiPEA (4.0 mmol), 2P-
MCM-41-Pd(OAc)2 (5 mol%), CO (5 bar), toluene (2 mL), 110 °C, 24 h; iso-
lated yields are given.
O
O
O
N
S
Cl
N
N
Cl
Cl
Cl
CO2Me
3d', 86%
3c', 79%
3e', 85%
O
N
O
O
O
O
O
in 79 and 84% yield, respectively. Furthermore, 5- or 4-fluo-
ro or chloro-substituted 2-iodoanilines 1c–f displayed good
reactivity and gave 7- or 6-fluoro or chloro-substituted 2-
arylbenzoxazinones 3z–f′ in 75–86% yield. It is noteworthy
that 5- or 4-bromo-2-iodoanilines 1g and 1h underwent
this transformation chemoselectively with various aryl io-
dides, providing the corresponding 7- or 6-bromo-substi-
tuted 2-arylbenzoxazinones 3g′-j′ in high yields. However,
4-cyano-2-iodoaniline (1i) with a strong electron-with-
drawing substituent led to the target product 3k′ in only
56% yield due to the low reactivity difference between 4-
cyano-2-iodoaniline (1i) and iodobenzene (2a), which re-
duces the chemoselectivity of the initial oxidative addition
of aryl iodide to Pd(0). In addition, we also performed car-
Br
N
N
Br
3g', 79%
3h', 87%
Br
3f', 78%
O
N
O
O
NC
Br
O
O
O
N
N
Br
3k', 56%
3i', 81%
3j', 80%
a Reaction conditions: 1 (1.2 mmol), 2 (1.0 mmol), DiPEA (4.0 mmol), 2P-
MCM-41-Pd(OAc)2 (5 mol%), toluene (2 mL) at 110 °C under 5 bar of CO for
24 h; isolated yields are given.
To confirm that the observed catalysis results from the
palladium sites on the channel inner walls of the MCM-41
support and not from soluble Pd species leached from 2P-
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Z. Xu et al.
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Synthesis
MCM-41-Pd(OAc)2, the heterogeneity of the 2P-MCM-41-
Pd(OAc)2 complex was investigated by the hot filtration
test.24 We focused on the carbonylative coupling reaction of
2-iodoaniline (1a) and iodobenzene (2a). After the reaction
was carried out for 10 hours, we removed the catalyst from
the reaction mixture by filtration at 110 °C and the catalyst-
free solution was allowed to react further under identical
conditions for 14 hours. It was found that no increase in
conversion of iodobenzene 2a was observed in the solution,
indicating that the observed reaction should be attributed
only to heterogeneous Pd species. In addition, no palladium
species could be detected in the clear solution based on ICP-
AES analysis. These results confirm the fact that the 2P-
MCM-41-Pd(OAc)2 catalyst is stable under the optimized
reaction conditions and supports the heterogeneous nature
of the reaction.
CO
I
I
O
Pd-L
O
Pd-L
O
E
D
N
Ar
N
Ar
H
H
DiPEA
O
O
L-Pd(OAc)2
CO
DiPEA·HI
N
L-Pd(0)
Ar
Ar-I
3
L = 2P-MCM-41
2
I
O
+ DiPEA·HI
N
H
Ar
C
A
Ar
Pd(II)-L
I
A plausible mechanism for this heterogeneous palladi-
um-catalyzed carbonylative synthesis of 2-arylbenzoxazi-
none is shown in Scheme 3. Firstly, the 2P-MCM-41-
Pd(OAc)2 complex can be easily reduced to 2P-MCM-41-
Pd(0) in the presence of carbon monoxide. Oxidative addi-
tion of aryl iodide 2 to 2P-MCM-41-Pd(0) produces an
MCM-41-bound arylpalladium(II) complex intermediate A,
which is followed by migratory insertion of carbon monox-
ide, giving an MCM-41-bound acylpalladium(II) complex
intermediate B. Then intermediate B reacts immediately
with the amino group of 2-iodoaniline 1 in the presence of
DiPEA to give N-(2-iodophenyl)arylcarboxamide C and re-
generate 2P-MCM-41-Pd(0). After this initial amidation of
aryl iodide 2, another oxidative addition of intermediate C
to 2P-MCM-41-Pd(0) takes place to form intermediate D,
which then undergoes CO insertion to furnish intermediate
E. Subsequent intramolecular cyclization of intermediate E
in the presence of DiPEA affords the desired 2-arylbenzox-
azinone 3 and regenerates 2P-MCM-41-Pd(0) again to com-
plete the catalytic cycle. It is noteworthy that the initial oxi-
dative addition to 2P-MCM-41-Pd(0) is highly chemoselec-
tive for aryl iodide 2 because of the reactivity difference to
the electron-rich 2-iodoaniline 1.
CO
O
I
Pd(II)-L
+ DiPEA
NH2
Ar
I
1
B
Scheme 3 Proposed catalytic cycle
without any significant loss of activity. Additionally, the
palladium leaching in this supported catalyst was also
checked, and the Pd content of the recovered 2P-MCM-41-
Pd(OAc)2 catalyst after eight consecutive cycles was deter-
mined to be 0.36 mmol/g based on ICP-AES analysis, indi-
cating negligible palladium leaching.
For the practical application of the heterogeneous 2P-
MCM-41-Pd(OAc)2 catalyst, its ease of separation and recy-
clability are important factors to be examined. This immo-
bilized palladium catalyst can be readily separated and re-
covered via a simple filtration process. We next studied the
recycling of 2P-MCM-41-Pd(OAc)2 in the carbonylative cy-
clization reaction of 4-chloroiodobenzene (2f) with 2-iodo-
aniline (1a). Upon completion of the reaction, the reaction
mixture was diluted with ethyl acetate, and the catalyst was
separated by simple filtration and washed with distilled
water and acetone. After being dried under vacuum at 80 °C
for 2 hours, the recovered palladium catalyst was directly
employed in the next cycle using the same substrates under
identical conditions. As presented in Figure 2, the 2P-MCM-
41-Pd(OAc)2 complex can be recycled at least eight times
Figure 2 Recycling of the 2P-MCM-41-Pd(OAc)2 complex
In conclusion, we have developed a novel and practical
domino synthesis of 2-arylbenzoxazinones from commer-
cially available 2-iodoanilines and aryl iodides through a
heterogeneous palladium-catalyzed double carbonylation
procedure. In contrast to traditional methods for the syn-
thesis of 2-arylbenzoxazinones, this heterogeneous double
carbonylation strategy has many attractive features, includ-
ing: (a) the scope of both aryl iodide and 2-iodoaniline sub-
strates is broad, and a wide range of aryl iodides and vari-
ous 2-iodoanilines can be used; (b) the reaction provides a
wide variety of 2-arylbenzoxazinones in mostly good to ex-
cellent yields; (c) the reaction is highly atom-economic and
is tolerant of a wide range of functional groups; and (d) this
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–J

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immobilized palladium catalyst can be obtained via a sim-
ple preparative procedure from commercially available re-
agents, recovered by filtration of the reaction mixture, and
reused at least seven times without any apparent loss of
catalytic efficiency.
(2 × 10 mL) and dried over anhydrous MgSO4 and concentrated under
reduced pressure. The residue was purified by column chromatogra-
phy (silica gel, light PE–EtOAc, 10:1) to afford the desired product 3.
2-Phenyl-4H-benzo[d][1,3]oxazin-4-one (3a)25
Yield: 196.4 mg (88%); white solid; mp 124–126 °C.
1H NMR (400 MHz, CDCl3):  = 8.31–8.28 (m, 2 H), 8.23 (dd, J = 7.8, 1.0
Hz, 1 H), 7.84–7.79 (m, 1 H), 7.70–7.66 (m, 1 H), 7.58–7.48 (m, 4 H).
13C NMR (100 MHz, CDCl3):  = 159.5, 157.1, 147.0, 136.5, 132.6,
130.3, 128.7, 128.6, 128.3, 128.2, 127.2, 117.1.
All starting chemicals were purchased from different commercial
sources and used without further purification. Toluene was distilled
from sodium ketyl and stored under argon. (EtO)3Si(CH2)3N(CH2PPh2)2
was prepared by the reaction of paraformaldehyde and HPPh2 with
(EtO)3Si(CH2)3NH2 according to a literature procedure.23 Mesoporous
MCM-41 material was prepared by our previous method.20 Products
were isolated by column chromatography on silica gel (100–200
mesh) with a mixture of EtOAc and light petroleum ether as eluent.
The products were confirmed by the comparison of their spectra and
physical data with authentic samples. 1H and 13C NMR spectra were
recorded at 400 or 100 MHz with CDCl3 as the solvent and TMS as an
internal standard. Chemical shifts are reported in  (ppm) relative to
TMS. HRMS spectra were recorded using a Q-Tof spectrometer with
micromass MS software using electrospray ionization (ESI). Melting
points are uncorrected. The content of palladium was measured
based on ICP-AES analysis.
2-(p-Tolyl)-4H-benzo[d][1,3]oxazin-4-one (3b)25
Yield: 213.5 mg (90%); white solid; mp 137–139 °C.
1H NMR (400 MHz, CDCl3):  = 8.23 (dd, J = 7.8, 1.0 Hz, 1 H), 8.20 (d, J =
8.4 Hz, 2 H), 7.84–7.79 (m, 1 H), 7.68 (d, J = 8.0 Hz, 1 H), 7.52–7.47 (m,
1 H), 7.32 (d, J = 8.0 Hz, 2 H), 2.44 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 159.7, 157.4, 147.2, 143.4, 136.5,
129.5, 128.6, 128.3, 128.0, 127.5, 127.1, 117.0, 21.7.
2-(4-Methoxyphenyl)-4H-benzo[d][1,3]oxazin-4-one (3c)17d
Yield: 212.7 mg (84%); white solid; mp 151–152 °C.
1H NMR (400 MHz, CDCl3):  = 8.25–8.22 (m, 2 H), 8.19 (dd, J = 8.0, 1.2
Hz, 1 H), 7.78–7.75 (m, 1 H), 7.62 (d, J = 8.0 Hz, 1 H), 7.48–7.43 (m, 1
H), 6.98 (d, J = 8.8 Hz, 2 H), 3.88 (s, 3 H).
2P-MCM-41-Pd(OAc)2 Complex20h
A mixture of (EtO)3Si(CH2)3N(CH2PPh2)2 (0.927 g, 1.5 mmol) and
MCM-41 (2.0 g) in anhyd toluene (120 mL) was stirred at 110 °C for 24
h under argon. The solid product was filtered, washed with CHCl3 (20
mL), and dried under vacuum at 130 °C for 8 h. The resulting white
powdery solid was then treated with Me3SiCl (3.0 g) in anhyd toluene
(100 mL) at room temperature under stirring for 12 h. The product
was filtered, washed with acetone (2 × 30 mL), and dried under vacu-
um at 110 °C for 4 h to provide bidentate phosphino-modified mate-
rial 2P-MCM-41 (2.518 g) with a phosphorus content of 0.81 mmol g–
13C NMR (100 MHz, CDCl3):  = 163.3, 159.7, 157.1, 147.4, 136.4,
130.3, 128.5, 127.7, 126.9, 122.6, 116.7, 114.1, 55.5.
2-(m-Tolyl)-4H-benzo[d][1,3]oxazin-4-one (3d)17d
Yield: 185.1 mg (78%); white solid; mp 118–120 °C.
1H NMR (400 MHz, CDCl3):  = 8.22 (d, J = 8.0 Hz, 1 H), 8.12–8.07 (m, 2
H), 7.83–7.78 (m, 1 H), 7.67 (d, J = 8.0 Hz, 1 H), 7.49 (t, J = 7.4 Hz, 1 H),
7.41–7.35 (m, 2 H), 2.44 (s, 3 H).
1
.
13C NMR (100 MHz, CDCl3):  = 159.6, 157.3, 147.1, 138.6, 136.5,
A mixture of 2P-MCM-41 (1.00 g) and Pd(OAc)2 (86 mg, 0.38 mmol) in
anhyd acetone (30 mL) was stirred under reflux for 3 d under argon.
The resulting product was filtered, washed with distilled water and
acetone, and dried at 70 °C under vacuum for 8 h to afford 2P-MCM-
41-Pd(OAc)2 (1.032 g) as a light yellow powder. The content of palladi-
um was determined to be 0.37 mmol/g based on ICP analysis.
133.5, 130.2, 128.8, 128.6, 128.5, 128.1, 127.2, 125.6, 117.0, 21.3.
2-(4-Fluorophenyl)-4H-benzo[d][1,3]oxazin-4-one (3e)25
Yield: 209.8 mg (87%); white solid; mp 177–178 °C.
1H NMR (400 MHz, CDCl3):  = 8.36–8.30 (m, 2 H), 8.24 (dd, J = 8.0, 1.2
Hz, 1 H), 7.83 (t, J = 7.4 Hz, 1 H), 7.67 (d, J = 8.4 Hz, 1 H), 7.52 (t, J = 7.4
Hz, 1 H), 7.19 (t, J = 8.6 Hz, 2 H).
13C NMR (100 MHz, CDCl3):  = 165.6 (d, J = 252.8 Hz), 159.4, 156.3,
146.9, 136.6, 130.7 (d, J = 9.0 Hz), 128.7, 128.3, 127.2, 126.5 (d, J = 2.8
Hz), 116.9, 116.0 (d, J = 22.0 Hz).
Heterogeneous Palladium-Catalyzed Carbonylative Synthesis of 2-
Arylbenzoxazinones 3; General Procedure
To a 12 mL vial equipped with a magnetic stirring bar were added 2P-
MCM-41-Pd(OAc)2 (5 mol%), 2-iodoaniline 1 (1.2 mmol) and aryl io-
dide 2 (1.0 mmol) (if solid). The vial was purged with argon and then
aryl iodide 2 (1.0 mmol) (if liquid), DiPEA (4.0 mmol), and toluene (2
mL) were injected by syringe. The vial was placed in an alloy plate and
the plate was then transferred into a 300 mL autoclave under argon.
After the autoclave had been flushed with CO (3×), the CO pressure
was adjusted to 5 bar and the reaction was carried out for 24 h at 110
°C. Upon completion of the reaction, the autoclave was cooled to am-
bient temperature and the pressure was released cautiously. EtOAc
(10 mL) was then added and the resulting mixture was filtered. The
Pd catalyst was recovered, by washing with distilled water (2 × 5 mL)
and acetone (2 × 5 mL), followed by drying under vacuum at 80 °C for
2 h, and reused in the next cycle. The filtrate was washed with water
2-(4-Chlorophenyl)-4H-benzo[d][1,3]oxazin-4-one (3f)25
Yield: 237.1 mg (92%); white solid; mp 190 °C.
1H NMR (400 MHz, CDCl3):  = 8.24–8.20 (m, 3 H), 7.83–7.79 (m, 1 H),
7.66 (d, J = 8.0 Hz, 1 H), 7.54–7.45 (m, 3 H).
13C NMR (100 MHz, CDCl3):  = 159.2, 156.2, 146.8, 139.1, 136.6,
129.6, 129.1, 128.7, 128.6, 128.4, 127.2, 117.0.
2-(4-Bromophenyl)-4H-benzo[d][1,3]oxazin-4-one (3g)25
Yield: 265.8 mg (88%); white solid; mp 119–120 °C.
1H NMR (400 MHz, CDCl3):  = 8.24 (d, J = 7.6 Hz, 1 H), 8.17 (d, J = 8.4
Hz, 2 H), 7.84–7.81 (m, 1 H), 7.70–7.63 (m, 3 H), 7.53 (t, J = 7.4 Hz, 1
H).
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13C NMR (100 MHz, CDCl3):  = 159.2, 156.4, 146.8, 136.7, 132.1,
13C NMR (100 MHz, CDCl3):  = 158.7, 155.0, 146.3, 138.9, 136.9,
129.7, 129.2, 128.7, 128.5, 127.7, 127.3, 117.0.
135.9, 129.3, 129.2, 128.9, 127.7, 123.9, 117.2.
2-(3,4-Dichlorophenyl)-4H-benzo[d][1,3]oxazin-4-one (3h)26
2-(o-Tolyl)-4H-benzo[d][1,3]oxazin-4-one (3n)17d
Yield: 242.4 mg (83%); white solid; mp 171–172 °C.
Yield: 177.9 mg (75%); white solid; mp 119–120 °C.
1H NMR (400 MHz, CDCl3):  = 8.40 (d, J = 2.0 Hz, 1 H), 8.24 (d, J = 7.6
Hz, 1 H), 8.13 (dd, J = 8.4, 2.0 Hz, 1 H), 7.88–7.83 (m, 1 H), 7.69 (d, J =
8.0 Hz, 1 H), 7.60–7.53 (m, 2 H).
1H NMR (400 MHz, CDCl3):  = 8.25 (d, J = 8.0 Hz, 1 H), 8.03 (d, J = 7.6
Hz, 1 H), 7.85–7.80 (m, 1 H), 7.68 (d, J = 8.0 Hz, 1 H), 7.53 (t, J = 7.6 Hz,
1 H), 7.44–7.40 (m, 1 H), 7.35–7.30 (m, 2 H).
13C NMR (100 MHz, CDCl3):  = 159.0, 155.1, 146.5, 137.2, 136.8,
13C NMR (100 MHz, CDCl3):  = 159.7, 158.3, 146.9, 139.2, 136.5,
133.4, 130.9, 130.2, 130.1, 128.8, 128.7, 127.4, 127.2, 117.0.
131.9, 131.6, 130.2, 129.9, 128.5, 128.4, 127.3, 126.1, 116.8, 22.1.
2-[4-(Trifluoromethyl)phenyl]-4H-benzo[d][1,3]-oxazin-4-one
2-(2-Methoxyphenyl)-4H-benzo[d][1,3]oxazin-4-one (3o)25
(3i)17d
Yield: 197.6 mg (78%); white solid; mp 150–152 °C.
Yield: 227.1 mg (78%); white solid; mp 80–82 °C.
1H NMR (400 MHz, CDCl3):  = 8.25 (dd, J = 8.0, 1.2 Hz, 1 H), 7.88–7.80
(m, 2 H), 7.70 (d, J = 8.0 Hz, 1 H), 7.55–7.48 (m, 2 H), 7.09–7.02 (m, 2
H), 3.93 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 159.8, 158.7, 157.8, 147.1, 136.4,
133.2, 131.3, 128.4, 128.3, 127.3, 120.6, 117.0, 112.2, 56.1.
1H NMR (400 MHz, CDCl3):  = 8.38 (d, J = 8.4 Hz, 2 H), 8.21 (d, J = 8.0
Hz, 1 H), 7.85–7.80 (m, 1 H), 7.73 (d, J = 8.4 Hz, 2 H), 7.67 (d, J = 8.0 Hz,
1 H), 7.53 (t, J = 7.6 Hz, 1 H).
13C NMR (100 MHz, CDCl3):  = 158.9, 155.6, 146.4, 136.7, 133.9 (q, J =
32.6 Hz), 133.5, 128.9, 128.7, 128.6, 127.4, 125.7 (q, J = 3.7 Hz), 123.7
(q, J = 271.0 Hz), 117.1.
2-(2,4-Difluorophenyl)-4H-benzo[d][1,3]oxazin-4-one (3p)
Yield: 204.8 mg (79%); brown solid; mp 135–137 °C.
2-(4-Acetylphenyl)-4H-benzo[d][1,3]oxazin-4-one (3j)
1H NMR (400 MHz, CDCl3):  = 8.25 (dd, J = 8.0, 1.2 Hz, 1 H), 8.20–8.15
(m, 1 H), 7.87–7.82 (m, 1 H), 7.70 (d, J = 8.0 Hz, 1 H), 7.56 (t, J = 7.6 Hz,
1 H), 7.06–6.94 (m, 2 H).
13C NMR (100 MHz, CDCl3):  = 165.5 (d, J = 254.9 Hz), 165.3 (d, J =
255.2 Hz), 159.0, 154.1 (d, J = 6.4 Hz), 146.6, 136.7, 132.7 (dd, J = 10.3,
2.0 Hz), 128.8, 128.6, 127.4, 117.0, 112.0 (dd, J = 21.6, 3.7 Hz), 105.7,
105.6 (t, J = 25.4 Hz).
Yield: 225.5 mg (85%); white solid; mp 181–183 °C.
1H NMR (400 MHz, CDCl3):  = 8.41–8.38 (m, 2 H), 8.25 (d, J = 8.0 Hz, 1
H), 8.07 (d, J = 8.4 Hz, 2 H), 7.88–7.83 (m, 1 H), 7.72 (d, J = 8.0 Hz, 1 H),
7.58–7.54 (m, 1 H), 2.67 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 197.4, 159.1, 156.1, 146.6, 139.9,
136.7, 134.2, 128.8, 128.7, 128.6, 128.5, 127.5, 117.1, 26.8.
HRMS (ESI): m/z [M]+ calcd for C16H11NO3: 265.0739; found:
HRMS (ESI): m/z [M]+ calcd for C14H7F2NO2: 259.0445; found:
265.0737.
259.0448.
Methyl 4-(4-Oxo-4H-benzo[d][1,3]oxazin-2-yl)benzoate (3k)
2-(1-Naphthyl)-4H-benzo[d][1,3]oxazin-4-one (3q)27
Yield: 236.3 mg (84%); white solid; mp 166–167 °C.
Yield: 226.8 mg (83%); white solid; mp 138 °C.
1H NMR (400 MHz, CDCl3):  = 8.38 (d, J = 8.4 Hz, 2 H), 8.26 (dd, J = 7.8,
1.0 Hz, 1 H), 8.17 (d, J = 8.4 Hz, 2 H), 7.87–7.83 (m, 1 H), 7.72 (d, J = 8.0
Hz, 1 H), 7.59–7.54 (m, 1 H), 3.97 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 166.3, 159.2, 156.2, 146.7, 136.7,
134.2, 133.6, 129.9, 128.8, 128.7, 128.3, 127.5, 117.2, 52.4.
1H NMR (400 MHz, CDCl3):  = 9.14 (d, J = 8.8 Hz, 1 H), 8.30 (dd, J = 7.4,
1.0 Hz, 1 H), 8.27 (dd, J = 8.0, 1.2 Hz, 1 H), 8.02 (d, J = 8.0 Hz, 1 H), 7.90
(d, J = 8.0 Hz, 1 H), 7.84–7.81 (m, 1 H), 7.77 (d, J = 8.0 Hz, 1 H), 7.67–
7.62 (m, 1 H), 7.59–7.51 (m, 3 H).
13C NMR (100 MHz, CDCl3):  = 159.7, 157.7, 146.8, 136.6, 134.1,
133.2, 130.8, 130.1, 128.9, 128.6, 128.5, 127.9, 127.4, 127.0, 126.4,
125.8, 124.8, 117.0.
HRMS (ESI): m/z [M]+ calcd for C16H11NO4: 281.0688; found:
281.0693.
2-(3-Thienyl)-4H-benzo[d][1,3]oxazin-4-one (3r)
4-(4-Oxo-4H-benzo[d][1,3]oxazin-2-yl)benzonitrile (3l)
Yield: 197.2 mg (86%); white solid; mp 102–104 °C.
Yield: 114.2 mg (46%); white solid; mp 227–228 °C.
1H NMR (400 MHz, CDCl3):  = 8.28 (d, J = 2.4 Hz, 1 H), 8.21 (d, J = 7.6
Hz, 1 H), 7.83–7.77 (m, 2 H), 7.63 (d, J = 8.0 Hz, 1 H), 7.49 (t, J = 7.6 Hz,
1 H), 7.40 (dd, J = 5.0, 3.8 Hz, 1 H).
13C NMR (100 MHz, CDCl3):  = 159.5, 153.9, 147.1, 136.6, 133.4,
130.7, 128.6, 128.1, 127.0, 126.8, 116.9.
1H NMR (400 MHz, CDCl3):  = 8.43 (d, J = 8.4 Hz, 2 H), 8.27 (d, J = 8.0
Hz, 1 H), 7.88 (t, J = 7.6 Hz, 1 H), 7.82 (d, J = 8.4 Hz, 2 H), 7.74 (d, J = 8.0
Hz, 1 H), 7.59 (t, J = 7.4 Hz, 1 H).
13C NMR (100 MHz, CDCl3):  = 158.8, 155.3, 146.4, 136.9, 134.3,
132.5, 129.2, 128.8, 128.7, 127.6, 117.9, 117.2, 115.7.
HRMS (ESI): m/z [M]+ calcd for C12H7NO2S: 229.0197; found:
229.0196.
HRMS (ESI): m/z [M]+ calcd for C15H8N2O2: 248.0586; found:
248.0579.
2-(2-Thienyl)-4H-benzo[d][1,3]oxazin-4-one (3s)27
2-(4-Nitrophenyl)-4H-benzo[d][1,3]oxazin-4-one (3m)14c
Yield: 199.5 mg (87%); white solid; mp 133–135 °C.
Yield: 107.3 mg (40%); yellow solid; mp 204–205 °C.
1H NMR (400 MHz, CDCl3):  = 8.22 (dd, J = 7.8, 1.0 Hz, 1 H), 7.97 (dd,
J = 3.8, 1.0 Hz, 1 H), 7.81 (t, J = 7.4 Hz, 1 H), 7.65–7.60 (m, 2 H), 7.49 (t,
J = 7.4 Hz, 1 H), 7.18 (dd, J = 5.0, 3.8 Hz, 1 H).
1H NMR (400 MHz, CDCl3):  = 8.52–8.49 (m, 2 H), 8.37 (d, J = 8.8 Hz, 2
H), 8.28 (dd, J = 7.8, 1.0 Hz, 1 H), 7.92–7.87 (m, 1 H), 7.76 (d, J = 8.0 Hz,
1 H), 7.63–7.58 (m, 1 H).
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–J

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13C NMR (100 MHz, CDCl3):  = 159.1, 153.8, 147.1, 136.6, 134.3,
132.4, 131.8, 128.8, 128.3, 128.0, 126.9, 116.8.
1H NMR (400 MHz, CDCl3):  = 8.25–8.22 (m, 1 H), 7.99 (s, 1 H), 7.76
(d, J = 4.8 Hz, 1 H), 7.59 (dd, J = 8.2, 1.4 Hz, 1 H), 7.52 (d, J = 8.4 Hz, 1
H), 7.39 (dd, J = 5.0, 3.0 Hz, 1 H), 2.46 (s, 3 H).
6-Methyl-2-phenyl-4H-benzo[d][1,3]oxazin-4-one (3t)28
13C NMR (100 MHz, CDCl3):  = 159.6, 153.3, 144.9, 138.5, 137.8,
133.5, 130.2, 128.2, 127.0, 126.8, 126.7, 116.6, 21.3.
Yield: 196.9 mg (83%); white solid; mp 114–115 °C.
HRMS (ESI): m/z [M]+ calcd for C13H9NO2S: 243.0354; found:
1H NMR (400 MHz, CDCl3):  = 8.29 (d, J = 7.6 Hz, 2 H), 8.03 (s, 1 H),
243.0363.
7.64–7.48 (m, 5 H), 2.48 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 159.8, 156.4, 144.9, 138.7, 137.8,
132.4, 130.4, 128.7, 128.2, 127.0, 116.7, 21.3.
7-Fluoro-2-phenyl-4H-benzo[d][1,3]oxazin-4-one (3z)
Yield: 180.9 mg (75%); white solid; mp 132–134 °C.
1H NMR (400 MHz, CDCl3):  = 8.31–8.26 (m, 2 H), 8.24 (dd, J = 8.8, 6.0
Hz, 1 H), 7.58 (t, J = 7.4 Hz, 1 H), 7.50 (t, J = 7.4 Hz, 2 H), 7.33 (dd, J =
9.2, 2.4 Hz, 1 H), 7.23–7.18 (m, 1 H).
13C NMR (100 MHz, CDCl3):  = 167.8 (d, J = 256.4 Hz), 158.6, 158.4,
149.5 (d, J = 13.3 Hz), 133.0, 131.3 (d, J = 10.8 Hz), 129.9, 128.8, 128.5,
116.6 (d, J = 23.2 Hz), 113.6, 113.3 (d, J = 22.4 Hz).
6-Methyl-2-(p-tolyl)-4H-benzo[d][1,3]oxazin-4-one (3u)
Yield: 218.6 mg (87%); white solid; mp 165–167 °C.
1H NMR (400 MHz, CDCl3):  = 8.15 (d, J = 7.2 Hz, 2 H), 7.99 (s, 1 H),
7.59 (d, J = 8.4 Hz, 1 H), 7.53 (d, J = 8.4 Hz, 1 H), 7.28 (d, J = 8.0 Hz, 2 H),
2.46 (s, 3 H), 2.41 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 159.8, 156.6, 145.0, 143.1, 138.4,
137.7, 129.5, 128.2, 128.1, 127.6, 126.9, 116.6, 21.7, 21.3.
HRMS (ESI): m/z [M]+ calcd for C14H8FNO2: 241.0539; found:
241.0533.
HRMS (ESI): m/z [M]+ calcd for C16H13NO2: 251.0946; found:
251.0938.
7-Fluoro-2-(4-methoxyphenyl)-4H-benzo[d][1,3]oxazin-4-one
(3a′)
2-(3,4-Dichlorophenyl)-6-methyl-4H-benzo[d][1,3]oxazin-4-one
(3v)
Yield: 216.9 mg (80%); white solid; mp 174–175 °C.
1H NMR (400 MHz, CDCl3):  = 8.27–8.20 (m, 3 H), 7.30 (dd, J = 9.2, 2.4
Hz, 1 H), 7.24–7.17 (m, 1 H), 7.01 (d, J = 8.8 Hz, 2 H), 3.90 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 167.8 (d, J = 255.4 Hz), 163.6, 158.8,
158.4, 149.9, 131.3 (d, J = 11.1 Hz), 130.5, 122.1, 116.1 (d, J = 23.6 Hz),
114.2, 113.3, 112.9 (d, J = 22.4 Hz), 55.5.
Yield: 251.1 mg (82%); white solid; mp 161–163 °C.
1H NMR (400 MHz, CDCl3):  = 8.37 (d, J = 2.0 Hz, 1 H), 8.10 (dd, J = 8.4,
2.0 Hz, 1 H), 8.02 (s, 1 H), 7.65 (dd, J = 8.4, 1.2 Hz, 1 H), 7.59–7.55 (m, 2
H), 2.50 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 159.2, 154.4, 144.3, 139.4, 138.0,
136.9, 133.4, 130.8, 130.3, 129.9, 128.4, 127.2, 127.1, 116.7, 21.4.
HRMS (ESI): m/z [M + H]+ calcd for C15H11FNO3: 272.0723; found:
272.0726.
HRMS (ESI): m/z [M + H]+ calcd for C15H10Cl2NO2: 306.0089; found:
306.0096.
6-Fluoro-2-phenyl-4H-benzo[d][1,3]oxazin-4-one (3b′)
Yield: 185.7 mg (77%); white solid; mp 137–139 °C.
Methyl 4-(6-Methyl-4-oxo-4H-benzo[d][1,3]oxazin-2-yl)benzoate
1H NMR (400 MHz, CDCl3):  = 8.20 (d, J = 7.6 Hz, 2 H), 7.79 (dd, J = 8.0,
2.8 Hz, 1 H), 7.62 (dd, J = 8.8, 4.8 Hz, 1 H), 7.51–7.39 (m, 4 H).
(3w)
Yield: 245.1 mg (83%); yellow solid; mp 175–176 °C.
13C NMR (100 MHz, CDCl3):  = 161.4 (d, J = 249.2 Hz), 158.8, 156.5,
143.6, 132.7, 130.0, 129.6 (d, J = 8.1 Hz), 128.8, 128.2, 124.7 (d, J = 23.5
Hz), 118.3 (d, J = 8.6 Hz), 113.9 (d, J = 24.1 Hz).
1H NMR (400 MHz, CDCl3):  = 8.35 (d, J = 8.8 Hz, 2 H), 8.15 (d, J = 8.4
Hz, 2 H), 8.04 (s, 1 H), 7.65 (dd, J = 8.0, 1.6 Hz, 1 H), 7.60 (d, J = 8.0 Hz,
1 H), 3.96 (s, 3 H), 2.50 (s, 3 H).
HRMS (ESI): m/z [M + H]+ calcd for C14H9FNO2: 242.0617; found:
13C NMR (100 MHz, CDCl3):  = 166.3, 159.4, 155.4, 144.5, 139.4,
242.0612.
137.9, 134.3, 133.3, 129.8, 128.3, 128.1, 127.3, 116.8, 52.4, 21.4.
HRMS (ESI): m/z [M]+ calcd for C17H13NO4: 295.0845; found:
295.0847.
7-Chloro-2-phenyl-4H-benzo[d][1,3]oxazin-4-one (3c′)
Yield: 203.6 mg (79%); white solid; mp 190–192 °C.
6-Methyl-2-(1-naphthyl)-4H-benzo[d][1,3]oxazin-4-one (3x)
1H NMR (400 MHz, CDCl3):  = 8.28 (d, J = 7.6 Hz, 2 H), 8.15 (d, J = 8.4
Hz, 1 H), 7.68 (d, J = 1.6 Hz, 1 H), 7.59 (t, J = 7.4 Hz, 1 H), 7.51 (t, J = 7.6
Hz, 2 H), 7.46 (dd, J = 8.4, 2.0 Hz, 1 H).
13C NMR (100 MHz, CDCl3):  = 158.8, 158.3, 148.1, 143.0, 133.0,
129.9, 129.8, 128.8, 128.7, 128.5, 127.0, 115.4.
Yield: 226.9 mg (79%); yellow solid; mp 112–114 °C.
1H NMR (400 MHz, CDCl3):  = 9.14 (d, J = 8.8 Hz, 1 H), 8.29 (d, J = 6.8
Hz, 1 H), 8.07 (s, 1 H), 8.02 (d, J = 8.0 Hz, 1 H), 7.91 (d, J = 8.0 Hz, 1 H),
7.67–7.57 (m, 3 H), 7.56–7.51 (m, 2 H), 2.50 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 159.9, 156.9, 144.7, 139.1, 137.8,
134.1, 133.0, 130.8, 129.9, 128.8, 128.1, 127.8, 127.2, 127.1, 126.4,
125.9, 124.8, 116.7, 21.4.
HRMS (ESI): m/z [M]+ calcd for C14H8ClNO2: 257.0244; found:
257.0251.
HRMS (ESI): m/z [M + H]+ calcd for C19H14NO2: 288.1025; found:
288.1014.
Methyl 4-(7-Chloro-4-oxo-4H-benzo[d][1,3]oxazin-2-yl)benzoate
(3d′)
Yield: 271.5 mg (86%); white solid; mp 173–174 °C.
1H NMR (400 MHz, CDCl3):  = 8.36 (d, J = 8.8 Hz, 2 H), 8.19–8.16 (m, 3
H), 7.72 (d, J = 1.6 Hz, 1 H), 7.51 (dd, J = 8.4, 2.0 Hz, 1 H), 3.97 (s, 3 H).
6-Methyl-2-(3-thienyl)-4H-benzo[d][1,3]oxazin-4-one (3y)
Yield: 204.4 mg (84%); white solid; mp 132–134 °C.
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–J

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Z. Xu et al.
Paper
Synthesis
13C NMR (100 MHz, CDCl3):  = 166.2, 158.4, 157.4, 147.7, 143.2,
133.9, 133.7, 130.0, 129.9, 129.3, 128.4, 127.3, 115.5, 52.5.
HRMS (ESI): m/z [M + H]+ calcd for C16H11ClNO4: 316.0377; found:
316.0388.
1H NMR (400 MHz, CDCl3):  = 8.36 (d, J = 2.0 Hz, 1 H), 8.29 (d, J = 7.6
Hz, 2 H), 7.91 (dd, J = 8.8, 2.0 Hz, 1 H), 7.61–7.55 (m, 2 H), 7.52 (t, J =
7.6 Hz, 2 H).
13C NMR (100 MHz, CDCl3):  = 158.3, 157.5, 145.9, 139.7, 132.9,
131.1, 129.9, 128.9, 128.8, 128.4, 121.5, 118.4.
7-Chloro-2-(3-thienyl)-4H-benzo[d][1,3]oxazin-4-one (3e′)
4-Oxo-2-phenyl-4H-benzo[d][1,3]oxazine-6-carbonitrile (3k′)
Yield: 224.1 mg (85%); light green solid; mp 137–139 °C.
Yield: 138.9 mg (56%); yellow solid; mp 127–129 °C.
1H NMR (400 MHz, CDCl3):  = 8.30–8.28 (m, 1 H), 8.14 (d, J = 8.4 Hz, 1
H), 7.77 (d, J = 5.2 Hz, 1 H), 7.64 (d, J = 2.0 Hz, 1 H), 7.44 (dd, J = 8.4, 2.0
Hz, 1 H), 7.43–7.40 (m, 1 H).
13C NMR (100 MHz, CDCl3):  = 158.7, 155.0, 148.3, 143.0, 133.0,
131.4, 129.9, 128.6, 127.1, 126.9, 126.8, 115.3.
1H NMR (400 MHz, CDCl3):  = 8.53 (d, J = 2.0 Hz, 1 H), 8.33 (d, J = 7.6
Hz, 2 H), 8.03 (dd, J = 8.4, 2.0 Hz, 1 H), 7.79 (d, J = 8.4 Hz, 1 H), 7.65 (t,
J = 7.4 Hz, 1 H), 7.55 (t, J = 7.6 Hz, 2 H).
13C NMR (100 MHz, CDCl3):  = 159.7, 157.6, 149.9, 138.7, 133.7,
133.4, 129.4, 129.0, 128.9, 128.5, 117.8, 117.3, 111.8.
HRMS (ESI): m/z [M]+ calcd for C15H8N2O2: 248.0586; found:
HRMS (ESI): m/z [M]+ calcd for C12H6ClNO2S: 262.9808; found:
262.9811.
248.0591.
6-Chloro-2-phenyl-4H-benzo[d][1,3]oxazin-4-one (3f′)
Yield: 200.8 mg (78%); white solid; mp 195–197 °C.
Funding Information
1H NMR (400 MHz, CDCl3):  = 8.29 (d, J = 7.2 Hz, 2 H), 8.20 (d, J = 2.4
Hz, 1 H), 7.76 (dd, J = 8.8, 2.4 Hz, 1 H), 7.64 (d, J = 8.4 Hz, 1 H), 7.61 (t,
J = 7.2 Hz, 1 H), 7.52 (t, J = 7.4 Hz, 2 H).
13C NMR (100 MHz, CDCl3):  = 158.5, 157.4, 145.5, 136.9, 133.9,
132.9, 129.9, 128.8, 128.7, 128.4, 128.0, 118.1.
We thank the National Natural Science Foundation of China (No.
21462021), the Natural Science Foundation of Jiangxi Province of Chi-
na (No. 20161BAB203086), and Key Laboratory of Functional Small
Organic Molecule, Ministry of Education (No. KLFS-KF-201704) for fi-
HRMS (ESI): m/z [M + H]+ calcd for C14H9ClNO2: 258.0322; found:
nancial support.
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Supporting Information
7-Bromo-2-phenyl-4H-benzo[d][1,3]oxazin-4-one (3g′)14c
Yield: 238.6 mg (79%); yellow solid; mp 172–174 °C.
Supporting information for this article is available online at
1H NMR (400 MHz, CDCl3):  = 8.29 (d, J = 7.6 Hz, 2 H), 8.07 (d, J = 8.4
Hz, 1 H), 7.87 (d, J = 1.2 Hz, 1 H), 7.62 (dd, J = 8.4, 1.6 Hz, 1 H), 7.58 (t,
J = 7.2 Hz, 1 H), 7.51 (t, J = 7.6 Hz, 2 H).
https://doi.org/10.1055/s-0039-1690265.
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References
13C NMR (100 MHz, CDCl3):  = 158.9, 158.3, 148.0, 133.0, 131.6,
131.5, 130.2, 129.9, 129.8, 128.8, 128.5, 115.8.
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7-Bromo-2-(4-bromophenyl)-4H-benzo[d][1,3]oxazin-4-one (3h′)
Yield: 331.4 mg (87%); white solid; mp 169–170 °C.
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1H NMR (400 MHz, CDCl3):  = 8.14 (d, J = 8.8 Hz, 2 H), 8.07 (d, J = 8.4
Hz, 1 H), 7.86 (d, J = 1.6 Hz, 1 H), 7.67–7.62 (m, 3 H).
13C NMR (100 MHz, CDCl3):  = 158.6, 157.5, 147.8, 132.2, 131.9,
131.7, 130.2, 129.9, 129.8, 128.8, 128.2, 115.7.
HRMS (ESI): m/z [M + H]+ calcd for C14H8Br2NO2: 379.8922; found:
379.8927.
7-Bromo-2-(1-naphthyl)-4H-benzo[d][1,3]oxazin-4-one (3i′)
Yield: 285.2 mg (81%); white solid; mp 168–170 °C.
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1H NMR (400 MHz, CDCl3):  = 9.16 (d, J = 8.4 Hz, 1 H), 8.35–8.32 (m, 1
H), 8.12 (d, J = 8.4 Hz, 1 H), 8.06 (d, J = 8.4 Hz, 1 H), 7.97 (d, J = 1.6 Hz,
1 H), 7.93 (d, J = 8.0 Hz, 1 H), 7.69–7.64 (m, 2 H), 7.61–7.56 (m, 2 H).
13C NMR (100 MHz, CDCl3):  = 159.1, 158.7, 147.8, 134.1, 133.7,
132.0, 131.6, 130.8, 130.4, 130.3, 129.8, 128.9, 128.1, 126.5, 126.4,
125.8, 124.8, 115.8.
HRMS (ESI): m/z [M + H]+ calcd for C18H11BrNO2: 351.9973; found:
351.9964.
6-Bromo-2-phenyl-4H-benzo[d][1,3]oxazin-4-one (3j′)14c
Yield: 241.6 mg (80%); white solid; mp 179–181 °C.
© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–J

J
Z. Xu et al.
Paper
Synthesis
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© 2019. Thieme. All rights reserved. Synthesis 2019, 51, A–J