Oxidative amidation of aromatic ethers catalyzed by rhodium acetate

Article abstract of DOI:10.1002/chem.201102303

Rocky rhodium: The oxidative amidation of aromatic ethers with no substituents in the para position catalyzed by rhodium acetate was achieved in moderate yields (see scheme) by using ditrifluoroacetoxyiodobenzene as the oxidant under mild conditions (RT).

Full text of DOI:10.1002/chem.201102303

COMMUNICATION
DOI: 10.1002/chem.201102303
Oxidative Amidation of Aromatic Ethers Catalyzed by Rhodium Acetate
Yu-Xing Deng, Jiang-Ping Xie, Wen-Wen Zhang, Ping Yin, Jing Yu, and Ling He*[a]
À
Construction of C N bonds catalyzed by transition-metal
complexes is a fascinating methodology for producing many
natural products and biologically active compounds.[1] More-
over, as far as we know, quinones could also play a key role
in the preparation of many natural substances and pharma-
cologically active molecules,[2] such as antibiotics based on
natural pigments, anthraquinones contained in rhubarb, ali-
zarin used for hemostasis in gamene, and naphthoquinone
derivatives from lithospermi used in anticancer treatment.
Therefore, to extend the methodology and disclose bioactive
molecules, we have studied the catalytic amidation reaction
of cyclic ethers.[3]
ketenes to give derivatives of 1-oxa-4-azaspiroACTHNGUTERN[UNG 4.5]deca-6,9-
dien-8-one. Herein, we propose a method for the oxidation
of a series of arenes that have no substituents in the para-
position, and concomitant intramolecular amidation of the
aromatic ethers within them by using PhI
(CF3CO2)2) as the oxidant to form azaspiroquinones
(Scheme 1).
ACHTUNGRTENUN(NG OAc)2 (or PhI-
AHCTUNGTRENNUNG
Recently, we found that rhodium acetate could activate
the oxidation of arenes to give the corresponding quinones
in good yield and concomitant amidation of ethers to form
Scheme 1. Synthetic procedure for the spiroquinone derivatives (Ts=tol-
the derivatives of 4-tosyl-1-oxa-4-azaspiroACTHNUTRGNE[NUG 4.5]deca-6,9-dien-
uenesulphonyl).
8-one in moderate yields. Although a series of studies[1] on
À
catalyzed inter- or intramolecular amidation reactions of C
H bonds have demonstrated that the method can effectively
In our previous work, we applied several cyclic ethers to
form carbon–nitrogen bonds in systems containing either sp2
and sp C H bonds, the oxidation and concomitant intramo-
the amidation reaction. Utilizing the intermolecular C N
À
3
À
bond formation catalyzed by copper(II) trifluoromethane
sulfonate and rhodium acetate, which provided a convenient
way to form N-substituted amino cyclic ethers,[3] we found
that almost all substrates could give their corresponding
products in good yields for which the amino group is always
added to the a-position of the substrate. However, when
testing the universality of the catalytic system on aromatic
ethers that were connected to the nitrogen source, we found
that these reactions could only give the oxidative amidation
lecular amidation of nitrogen atoms transferring to the allyl-
ic position of ketenes are sparse in the literature. There are
a few reports on compounds substituted with electron-do-
nating groups, such as aromatic ethers, with -OH or -OCH3
groups in the para position giving the cyclic reaction prod-
ucts.[4] However, the use of rhodium acetate as the catalyst
has not yet been reported and so, in our search for this reac-
tion, we faced the following challenges: first, the accom-
plishment of the reaction under mild conditions with a wide
substrate scope; second, the discovery of a highly selective
one-pot reaction method for the oxidative amidation; and
third, the use of simple, instead of complicated, catalysts.
Therefore, it is interesting and important to develop a more
convenient method, with respect to these considerations, for
the oxidation of aromatic ethers and the intramolecular ami-
dation of the a position of ethers and the allylic position of
À
products (2), and the ortho-position intramolecular C H in-
sertion product (3) of the reaction of the aromatic ether
with b-NHTs was undetected in the reaction system
(Scheme 2).
At the beginning of this work, we studied the effects of
the oxidant and catalyst on the amidation reactions for the
purpose of developing a mild and environmentally friendly
methodology. The effects of oxidant and catalyst are shown
in Table 1. It was found that only rhodium(II) acetate could
[a] Y.-X. Deng,+ J.-P. Xie,+ W.-W. Zhang, P. Yin, J. Yu, Prof. Dr. L. He
Key Laboratory of Drug Targeting and Drug-Delivery Systems of
the Ministry of Education, Department of Medicinal Chemistry
West China School of Pharmacy, Sichuan University
Chengdu, Sichuan,610041 (P. R. China)
Fax : (+86)28-85502940
E-mail: lhe2001@yahoo.com.cn
[+] These authors contributed equally to this work.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201102303.
Scheme 2. The oxidation–amidation reaction.
Chem. Eur. J. 2012, 18, 1077 – 1082
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1077

Table 1. Effect of catalysts and oxidants on the amidation reaction.[a]
Catalyst
Oxidant
Yield of
2a [%][b]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
–
V
PhI
PhI
PhI
PhI
PhI
PhI
PhI
PhI
PhI
PhI
N
–
trace
–
E
E
G
–
–
G
G
ꢀ20
trace
–
65
70
E
Rh
Rh
Rh
Rh
Rh
2A
2A(OAc)4 (5%)
2A(OAc)4 (5%)
2A(OAc)4 (5%)
2A(OAc)4 (5%)
E
U
PhI=O
MnO2
O2
trace
0
Figure 1. X-ray crystal structure of 4-tosyl-1-oxa-4-azaspiroACTHNUTRGENUGN[4.5]deca-6,9-
dien-8-one. Thermal ellipsoids were drawn at the 50% probability.
CHTUNGTRENNUNG
E
0
Cu(CF3COCH2COCF3) (20%)
PhI
trace
under the reaction conditions. From these results, we con-
clude that this method provides a convenient and mild
15
N
PhI
N
trace
method for the preparation of 1-oxa-4-azaspiroACTHNURTGNEU[GN 4.5]deca-6,9-
dien-8-one derivatives. At the same time, the reaction pro-
ceeded in a one-pot manner, giving rise to the intermolecu-
16
17
CuI (20%)
[Ru3(CO)12] (20%)
PhI
PhI
N
–
–
E
[a] Reaction conditions: substrate (1 mmol), oxidant (2.5 mmol), Al2O3
(2.5 mmol), CH2Cl2 as the solvent, room temperature, 4 ꢁ molecular
sieves (TTP=meso-tetra-kisACHTNUTRGNE(NUG p-tolyl)porphyrinato). [b] Isolated yield
À
lar formation of a C O bond and the intramolecular forma-
À
tion of a C N bond. In a few rare cases, the aromatic ethers
based on the amount of compound 1a consumed.
containing no para substituents gave the products of oxida-
À
tion and C H insertion.
Specifically, from Table 2, we can easily see the impact of
electronic effects on the oxidation of aromatic ethers and
the nucleophilic attack of the nitrogen. The effect of sub-
stituents makes the oxidative amidation reaction more rapid
in the presence of aromatic ether derivatives with electron-
donating groups. Electron-withdrawing substituents on the
aromatic ring resulted in moderate yields and the TLCs
showed only one product. Thus, the reaction rates depend
on the oxidation of the substrate. Furthermore, the yields of
the azaspiroquinones rely on the activity of the nitrogen
source. Ultimately, the reactivity and selectivity depend on
the presence of an appropriate oxidant and reactive nitrogen
be used as the catalyst for the oxidative amidation of aro-
matic ethers (Table 1, entries 9 and 10). Other metal com-
plexes, such as Cu
ACHTUNGTRENNUNG(acac)2 (acac=acetylacetonate) and V-
ACHTUNGTRENNUNG
we found that the yield increased only marginally when in-
creasing the loading of rhodium acetate from 5 to 10%. In
addition, only PhIACHTUNGTRENNUNG(OAc)2 and PhIHCATUNGTNERN(UGN CF3CO2)2 were employed
effectively as the oxidant for the oxidative amidation of aro-
matic ethers (Table 1, entries 9 and 10). Furthermore, we
succeeded in getting a higher yield when the loading of PhI-
ACHTUNGTRENNUNG(CF3CO2)2 was increased from 2.5 to 5 equivalents. Thus, the
À
product
4-tosyl-1-oxa-4-azaspiro
U
source, which depends especially on the N H dissociation
energies of the nitrogen source.
A hypothetical mechanism[4c,6] for the oxidative amidation
reaction of the aromatic ethers with b-NHTs is depicted in
Scheme 3. We speculate that the product may be formed in
this manner, as previously described in the work of Chiba
et al.[6a] and Sanford et al.[6g] A tentative mechanism was
proposed as follows. First, a proton on the nitrogen of 4-
methyl-N-(2-phenoxyethyl)benzenesulfonamide leaves in
the presence of diacetoxyiodobenzene and the rhodium(II)
ratio of 1:2.5:2.5:0.05 of substrate/PhIACTHNUTRGNEG(UN CF3CO2)2/Al2O3/rho-
dium acetate. The structure was confirmed by single crystal
X-ray spectroscopy (Figure 1),[5] as well as H and 13C NMR
spectroscopy and high resolution MS.
To evaluate the solvent effects, we studied the oxidative
amidation reaction of substituted aromatic ethers by using
different solvents, such as CH2Cl2, ClCH2CH2Cl, and
CH3CN. However, the yields in all solvents were similar
under otherwise identical experimental conditions. As a
result, CH2Cl2 was used as the solvent for subsequent stud-
ies.
Next, we applied different aromatic ethers to the oxida-
tive amidation reaction. All of the substrates (n=1) gave
their corresponding products in moderate yields (Table 2).
Unfortunately, the aromatic ethers (1) with n=2 gave only
trace amounts of the corresponding spiroquinone products
salt to form a rhodium
ACHTUNGTRENNUNG
complex may then couple with the iodine in PhIACHTUNGTRENNUNG
such a way as to also form C N and C Rh bonds simultane-
ously at the 1 and 4 positions of the benzene ring. Second,
À
À
an OAc group in PhIACHTNUTRGNE(NUG OAc)2 nucleophilically attacks this
complex to form adduct II. Third, the adduct undergoes an
intermolecular hydrogen transfer to form cation III and re-
lease PhI and HOAc. Finally, compound III is unstable and
so eliminates HOAc (NaOAc) in NaOH (5%) solution to
afford the product, 4-tosyl-1-oxa-4-azaspiroACTHNURTGNEU[GN 4.5]deca-6,9-
dien-8-one (2).
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Chem. Eur. J. 2012, 18, 1077 – 1082

Oxidative Amidation of Aromatic Ethers
COMMUNICATION
Table 2. Intramolecular oxidation–amidation catalyzed by rhodium ace-
Table 2. (Continued)
Substrate
tate[a]
.
Product
Yield [%][b]
(conversion
[%])
Substrate
Product
Yield [%][b]
(conversion
[%])
12
13
14
15
63 (90)
94 (55)
35 (90)
40 (90)
1
2
70 (78)
54 (90)
61 (75)
64 (74)
67 (83)
48 (57)
64 (57)
91 (38)
90(40)
3
4
16
17
18
66 (54)
75 (34)
72 (90)
5
6
7
19
57 (70)
51 (65)
8
20
9
[a] Reaction conditions: substrateACTHNUTRGENNUG(1 mmol), PhIACHUTGNTRENN(UNG CF3CO2)2 (2.5 mmol), Al2O3
(2.5 mmol), Rh2ACTHNUTRGEN(UNG OAc)4, CH2Cl2 as the solvent, room temperature, 4 ꢁ mo-
lecular sieves. [b] Isolated yield based on the amount of compound 1 con-
sumed.
10
11
80 (24)
38 (90)
In conclusion, we have developed an efficient rhodium
acetate catalyzed procedure allowing aromatic ethers with
no para substituents to form derivatives of 4-tosyl-1-oxa-4-
azaspiroACTHNUTRGNE[UNG 4.5]deca-6,9-dien-8-one through an oxidation and
concomitant intramolecular amidation by using iodobenzene
diacetate as the oxidant under mild conditions. The reaction
Chem. Eur. J. 2012, 18, 1077 – 1082
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
1079

L. He et al.
90% conversion). 1H NMR (400 MHz, CDCl3): d=7.68 (d, J=8.4 Hz,
2H), 7.32 (d, J=8.4 Hz, 2H), 6.36 (d, J=10.0 Hz, 1H), 6.14 (dd, J=8.4,
2.0 Hz, 2H), 4.24–4.29 (m, 1H), 4.14–4.19 (m, 1H), 3.78–3.84 (m, 1H),
3.71–3.76 (m, 1H), 2.45 (s, 3H), 1.91 ppm (s, 3H); 13C NMR (50 MHz,
CDCl3): d=185.1, 154.9, 144.3, 142.6, 135.8, 129.9, 128.8, 127.9, 126.5,
88.1, 66.0, 47.3, 21.6, 17.8 ppm; HRMS (ESI+): m/z calcd for
C16H17NNaO4S: 342.0770 [M+Na]+; found: 342.0768.
6-Chloro-4-tosyl-1-oxa-4-azaspiroACTHNUTRGNE[NUG 4.5]deca-6,9-dien-8-one (2c): Following
the general procedure by using N-[2-(2-chlorophenoxy)ethyl]-4-methyl-
benzenesulfonamide as the substrate gave compound 2c (61% yield,
75% conversion). 1H NMR (400 MHz, CDCl3): d=7.71 (d, J=8.0 Hz,
2H), 7.32 (d, J=8.0 Hz, 2H), 6.57 (d, J=9.6 Hz, 1H), 6.43 (d, J=1.6 Hz,
1H), 6.24 (dd, J=9.6, 1.6 Hz, 1H), 4.42–4.37 (m, 1H), 4.24–4.19 (m, 1H),
3.80–3.77 (m, 1H), 2.45 ppm (m, 3H); 13C NMR (100 MHz, CDCl3): d=
183.3, 144.5, 143.5, 135.7, 129.7, 129.6, 128.3, 127.7, 87.6, 67.0, 47.3,
14.1 ppm; HRMS (ESI+): m/z calcd for C15H14ClNaO4S: 362.0224
[M+Na]+; found: 362.0227.
3’-Tosyl-4H-spiro(naphthalene-1,2’-oxazolidin)-4-one (2d): Following the
general procedure by using 4-methyl-N-[2-(naphthalen-1-yloxy)ethyl]ben-
zenesulfonamide as the substrate gave compound 2d (64% yield, 74%
conversion). 1H NMR (400 MHz, CDCl3): d=8.08 (d, J=7.6 Hz, 1H),
7.45 (t, J=7.6 Hz, 1H), 7.32 (t, J=7.6 Hz, 1H), 7.24 (d, J=8.0 Hz, 2H),
7.18 (d, J=7.6 Hz, 1H), 7.11 (d, J=8.0 Hz, 2H), 6.79 (d, J=10.0 Hz,
1H), 6.43 (d, J=10.0 Hz, 1H), 4.37–4.12 (m, 1H), 4.42–4.37 (m, 1H),
4.32–4.26 (m, 1H), 3:97–3:92 (m, 1H), 3.81–3.75 (m, 1H), 2.38 ppm (s,
3H); 13C NMR (100 MHz, CDCl3): d=183.7, 143.7, 143.2, 139.7, 135.6,
132.6, 131.3, 129.3, 129.2, 129.1, 127.1, 127.0, 126.3, 88.0, 65.5, 47.1,
21.4 ppm; HRMS (ESI+): m/z calcd for C19H17NNaO4S: 378.0778
[M+Na]+; found: 378.0782.
Scheme 3. Tentative mechanism for the oxidative amidation of aromatic
ethers.
proceeded through a highly selective oxidative amidation re-
À
action giving rise to the formation of an intermolecular C
À
O bond and an intramolecular C N bond, which could pro-
duce important intermediates in the synthesis of some bio-
logically active compounds. This method provides conven-
ient access to N-substituted oxazolidin and spiroquinone de-
rivatives. Further investigations into the pharmacological ac-
tivities of these heterocyclic compounds are underway and
will be reported in due course.
7,9-Dimethyl-4-tosyl-1-oxa-4-azaspiroACTHNUGTRNEUNG[4.5]deca-6,9-dien-8-one (2e): Fol-
lowing the general procedure by using N-[2-(3,5-dimethylphenoxy)ethyl]-
4-methylbenzenesulfonamide as the substrate gave compound 2e (67%
yield, 83% conversion). 1H NMR (400 MHz, CDCl3): d=7.62 (d, J=
8.0 Hz, 2H), 7.31 (d, J=8.0 Hz, 2H), 6.18 (s, 2H), 4.13 (t, J=2.0 Hz,
2H), 3.75–3.69 (m, 2H), 2.45 (s, 2H), 1.84 ppm (s, 6H); 13C NMR
(100 MHz, CDCl3): d=175.0, 144.1, 138.5, 138.4, 136.2, 129.5, 129.4,
127.8, 86.9, 65.0, 47.0, 29.7, 15.7 ppm; HRMS (ESI+): m/z calcd for
C17H19NNaO4S: 356.0927 [M+Na]+; found: 356.0929.
Experimental Section
6,7-Dimethyl-4-tosyl-1-oxa-4-azaspiroACTHNUGTRNEUNG[4.5]deca-6,9-dien-8-one (2 f): Fol-
lowing the general procedure by using N-[2-(2,3-dimethylphenoxy)ethyl]-
4-methylbenzenesulfonamide as the substrate gave compound 2 f (48%
yield, 57% conversion). 1H NMR (400 MHz, CDCl3): d=7.62 (d, J=
8.0 Hz, 2H), 7.30 (d, J=8.0 Hz, 2H), 6.40 (d, J=10.0 Hz, 1H), 6.15 (d,
J=10.0 Hz, 1H), 4.29–4.24 (m, 1H), 4.17–4.10 (m, 1H), 3.79 (t, J=
6.0 Hz, 2H), 2.44 (s, 3H) 1.85 (s, 3H), 1.72 ppm (s, 3H); 13C NMR
(100 MHz, CDCl3): d=184.7, 147.9, 144.1, 141.7, 134.3, 129.5, 128.5,
127.7, 124.7, 88.6, 65.6, 47.3, 21.5, 14.6, 11.2 ppm; HRMS (ESI+): m/z
calcd for C17H19NNaO4S: 356.0927 [M+Na]+; found: 356.0922.
General: All reactions were performed by using standard Schlenk tech-
niques under a nitrogen and argon atmosphere. Reagents were used after
purification. CH2Cl2 was distilled from P2O5 and stored under a nitrogen
atmosphere. Flash column chromatography was performed on silica gel.
1H and 13C NMR spectra were recorded on Bruker AC-E 200 MHz and
Varian Mercury 400 MHz spectrometers. The mass spectra (ESI/HRMS)
were recorded on a Bruker Daltonics Data analysis 3.2 mass spectrome-
ter.
General procedure for the amidation of substituted aromatic ethers: A
flame-dried round-bottom flask was charged, under a nitrogen atmos-
7-Chloro-4-tosyl-1-oxa-4-azaspiroACTHNUTRGNE[NUG 4.5]deca-6,9-dien-8-one (2g): Following
the general procedure by using N-[2-(3-chlorophenoxy)ethyl]-4-methyl-
benzenesulfonamide as the substrate gave compound 2g (64% yield,
57% conversion). 1H NMR (400 MHz, CDCl3): d=7.67 (d, J=8.0 Hz,
2H), 7.35 (d, J=8.0 Hz, 2H), 6.64 (dd, J=10.0, 2.8 Hz, 1H), 6.44 (d, J=
2.8 Hz, 1H), 6.31 (d, J=10.0 Hz, 1H), 4.22–4.12 (m, 2H), 3.85–3.80 (m,
1H), 3.67–3.62 (m, 1H), 2.46 ppm (s, 3H); 13C NMR (100 MHz, DMSO):
d=183.0, 150.9, 149.4, 146.1, 140.7, 137.1, 135.2, 132.9, 132.6, 92.4, 70.9,
51.9, 26.3 ppm; HRMS (ESI+): m/z calcd for C17H19NO5SNa: 362.0224
[M+Na]+; found: 362.0226.
phere, with the substrate (0.1 mmol), PhI
ACHTNUGTRNEN(UGN CF3CO2)2 (0.25 mmol,
2.5 equiv), Rh2A(OAc)4 (0.005 mmol, 5 mmol%), and distilled dichlorome-
CHTUNGTRENNUNG
thane (10 mL). The resulting mixture was stirred at room temperature
for 5 h. Then, the mixture was washed with NaOH (5%) and dried over
MgSO4. The filtrate was purified by flash column chromatography on
silica gel.
4-Tosyl-1-oxa-4-azaspiroACHTUNGTRENNUNG[4.5]deca-6,9-dien-8-one (2a): Following the gen-
eral procedure by using 4-methyl-N-(2-phenoxyethyl)benzenesulfona-
mide as the substrate gave compound 2a (70% yield, 78% conversion).
1H NMR (400 MHz, CDCl3): d=7.69 (d, J=8.4 Hz, 2H), 7.32 (d, J=
8.4 Hz, 2H), 6.49 (d, J=10.0 Hz, 2H), 6.20 (d, J=10.0 Hz, 2H), 4.17 (t,
J=6.0 Hz, 2H), 3.73 (t, J=6.0 Hz, 2H), 2.45 ppm (s, 3H); 13C NMR
(100 MHz, CDCl3): d=184.7, 144.3, 143.2, 129.6, 129.4, 127.7, 86.1, 65.5,
47.0, 29.6, 21.5 ppm; HRMS (ESI+): m/z calcd for C15H15NO4SNa:
328.0619 [M+Na]+; found: 328.0645.
6-Bromo-4-tosyl-1-oxa-4-azaspiroACTHNUTRGNE[NUG 4.5]deca-6,9-dien-8-one (2h): Following
the general procedure by using N-[2-(2-bromophenoxy)ethyl]-4-methyl-
benzenesulfonamide as the substrate gave compound 2h (91% yield,
38% conversion). 1H NMR (400 MHz, CDCl3): d=7.73 (d, J=8.4 Hz,
2H), 7.33 (d, J=8.4 Hz, 2H), 6.83 (d, J=1.6 Hz, 1H), 6.64 (d, J=
10.0 Hz, 1H), 6.27 (d, J=10.0 Hz, 1.6 Hz, 1H), 4.45–4.40 (m, 1H), 4.23–
4.18 (m, 1H), 3.80–3.77 (m, 2H), 2.45 ppm (s, 3H); 13C NMR (100 MHz,
DMSO): d=183.2, 147.1, 144.8, 144.6, 136.0, 133.7, 130.3, 127.9, 127.8,
87.7, 67.3, 47.4, 21.6 ppm; HRMS (ESI+): m/z calcd for C17H19NO5SNa:
405.9719 [M+Na]+; found: 405.9735.
6-Methyl-4-tosyl-1-oxa-4-azaspiroACTHNUTRGNE[UNG 4.5]deca-6,9-dien-8-one (2b): Follow-
ing the general procedure by using 4-methyl-N-[2-(ortho-tolyloxy)ethyl]-
benzenesulfonamide as the substrate gave compound 2b (54% yield,
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Oxidative Amidation of Aromatic Ethers
COMMUNICATION
6-Fluoro-4-tosyl-1-oxa-4-azaspiro
[4.5]deca-6,9-dien-8-one (2i): Following
66.1, 47.8 ppm; HRMS (ESI+): m/z calcd for C18H14N2O6SNa: 409.0465
[M+Na]+; found: 409.0464.
the general procedure by using N-[2-(2-fluorophenoxy)ethyl]-4-methyl-
benzenesulfonamide as the substrate gave compound 2i (90% yield,
40% conversion). 1H NMR (400 MHz, CDCl3): d=7.69 (d, J=8.4 Hz,
2H), 7.33 (d, J=8.4 Hz, 2H), 6.44 (t, J=10.0 Hz, 1H), 6.21 (dd, J=10.0,
0.8 Hz, 1H), 5.87 (dd, J=12.8, 2.0 Hz, 1H), 4.31–4.21 (m, 2H), 3.82–3.73
(m, 2H), 2.45 ppm (s, 3H); 13C NMR (100 MHz, DMSO): d=186.7,
186.5, 144.8, 144.2, 135.6, 130.4, 128.6, 127.8, 110.6, 85.6, 67.4, 47.6,
21.5 ppm; HRMS (ESI+): m/z calcd for C17H19NO5SNa: 346.0520
[M+Na]+; found: 346.0523.
4-(4-Methoxyphenylsulfonyl)-1-oxa-4-azaspiroACTHNUTRGNEUG[N 4.5]deca-6,9-dien-8-one
(2p): Following the general procedure by using 4-methoxy-N-(2-phenox-
yethyl)benzenesulfonamide as the substrate gave compound 2p (66%
yield, 54% conversion). 1H NMR (400 MHz, CDCl3): d=7.74 (d, J=
8.8 Hz, 2H), 6.98 (d, J=8.8 Hz, 2H), 6.51 (d, J=10.4 Hz, 2H), 6.20 (d,
J=10.4 Hz, 2H), 4.17 (t, J=6.0 Hz, 2H), 3.89 (s, 3H), 3.73 ppm (t, J=
6.0 Hz, 2H); 13C NMR (100 MHz, DMSO): d=185.3, 163.4, 145.1, 130.6,
130.2, 129.1, 115.0, 86.1, 65.8, 56.2, 47.2 ppm; HRMS (ESI+): m/z calcd
for C15H15NO5SNa: 344.0563 [M+Na]+; found: 344.0560.
6,7-Dichloro-4-tosyl-1-oxa-4-azaspiroACTHNUGTRNEUNG[4.5]deca-6,9-dien-8-one (2j): Fol-
lowing the general procedure by using N-[2-(2,3-dichlorophenoxy)ethyl]-
4-methylbenzenesulfonamide as the substrate gave compound 2j (80%
yield, 24% conversion). 1H NMR (400 MHz, CDCl3): d=7.66 (d, J=
8.4 Hz, 2H), 7.33 (d, J=8.4 Hz, 2H), 6.68 (d, J=10.0 Hz, 1H), 6.38 (d,
J=10.0 Hz, 1H), 4.44–4.39 (m, 1H), 4.27–4.22 (m, 1H), 3.89–3.84 (m,
1H), 3.82–3.75 (m, 1H), 2.46 ppm (s, 3H); 13C NMR (100 MHz, DMSO):
d=176.7, 149.1, 145.3, 144.8, 135.7, 132.8, 130.4, 127.8, 126.9, 88.8, 67.6,
47.4, 21.6 ppm; HRMS (ESI+): m/z calcd for C17H19NO5SNa: 395.9834
[M+Na]+; found: 395.9881.
6-Chloro-4-(4-methoxyphenylsulfonyl)-1-oxa-4-azaspiroACTHNUTRGENUGN[4.5]deca-6,9-
dien-8-one (2q): Following the general procedure by using N-[2-(2-chlor-
ophenoxy)ethyl]-4-methoxybenzenesulfonamide as the substrate gave
compound 2q (75% yield, 34% conversion). 1H NMR (400 MHz,
CDCl3): d=7.77 (d, J=8.8 Hz, 2H), 6.98 (d, J=8.8 Hz, 2H), 6.79 (d, J=
10.0 Hz, 1H), 6.42 (s, 1H), 6.25 (d, J=10.0 Hz, 1H), 4.42–4.37 (m, 1H),
4.25–4.20 (m, 1H), 3.89 (s, 3H), 3.78 ppm (t, J=6.4 Hz, 2H); 13C NMR
(100 MHz, DMSO): d=183.8, 163.5, 153.2, 144.9, 130.3, 130.1, 129.8,
127.9, 115.0, 87.3, 67.4, 56.3, 47.4 ppm; HRMS (ESI+): m/z calcd for
C15H14ClNO5SNa: 387.0173 [M+Na]+; found: 378.0175.
4-(4-Nitrophenylsulfonyl)-1-oxa-4-azaspiroACTHNUTRGNEU[GN 4.5]deca-6,9-dien-8-one (2k):
Following the general procedure by using 4-nitro-N-(2-phenoxyethyl)ben-
zenesulfonamide as the substrate gave compound 2k (38% yield, 90%
conversion). 1H NMR (400 MHz, CDCl3): d=8.39 (d, J=8.8 Hz, 2H),
8.01 (d, J=8.8 Hz, 2H), 6.48 (d, J=10.0 Hz, 2H), 6.26 (d, J=10.0 Hz,
2H), 4.22 (t, J=6.0 Hz, 2H), 3.77 ppm (t, J=6.0 Hz, 2H); 13C NMR
(100 MHz, DMSO): d=185.2, 150.5, 144.5, 144.4, 129.5, 125.2, 86.6, 66.0,
47.5 ppm; HRMS (ESI+): m/z calcd for C14H12N2O6SNa: 359.0308
[M+Na]+; found: 359.0303.
4-(4-Methoxyphenylsulfonyl)-6-methyl-1-oxa-4-azaspiroACTHNUTRGENUGN[4.5]deca-6,9-
dien-8-one (2r): Following the general procedure by using 4-methoxy-N-
[2-(ortho-tolyloxy)ethyl]benzenesulfonamide as the substrate gave com-
pound 2r (72% yield, 90% conversion). 1H NMR (400 MHz, CDCl3):
d=7.72 (d, J=8.4 Hz, 2H), 6.97 (d, J=8.4 Hz, 2H), 6.37 (d, J=10.0 Hz,
1H), 6.13 (d, J=10.0 Hz, 2H), 4.28–4.23 (m, 1H), 4.20–4.14 (m, 1H),
3.89 (s, 3H), 3.83–3.77 (m, 1H), 3.74–3.69 (m, 1H), 1.92 ppm (s, 3H);
13C NMR (100 MHz, DMSO): d=185.3, 163.4, 156.1, 144.6, 130.6, 130.1,
128.6, 128.2, 115.0, 87.8, 66.4, 56.2, 47.4, 17.7 ppm; HRMS (ESI+): m/z
calcd for C16H17NO5SNa: 358.0719 [M+Na]+; found: 358.0717.
6-Methyl-4-(4-nitrophenylsulfonyl)-1-oxa-4-azaspiroACHTNUTRGNEUNG[4.5]deca-6,9-dien-8-
one (2l): Following the general procedure by using 4-nitro-N-[2-(ortho-
tolyloxy)ethyl]benzenesulfonamide as the substrate gave compound 2l
(63% yield, 90% conversion). 1H NMR (400 MHz, CDCl3): d=8.39 (d,
J=8.8 Hz, 2H), 7.99 (d, J=8.8 Hz, 2H), 6.35 (d, J=9.6 Hz, 1H), 6.19 (d,
J=9.6 Hz, 2H), 4.34–4.29 (m, 1H), 4.22–4.16 (m, 1H), 3.86–3.74 (m,
2H), 1.88 ppm (s, 3H); 13C NMR (100 MHz, DMSO): d=184.8, 154.1,
150.4, 144.4, 141.9, 129.3, 129.2, 128.8, 124.4, 88.6, 66.1, 47.5, 17.8 ppm;
HRMS (ESI+): m/z calcd for C15H14N2O6SNa: 373.0465 [M+Na]+;
found: 373.0466.
4-(4-Methoxyphenylsulfonyl)-6,7-dimethyl-1-oxa-4-azaspiroACTHNUTRGNEUGN[4.5]deca-6,9-
dien-8-one (2s): Following the general procedure by using N-[2-(2,3-di-
methylphenoxy)ethyl]-4-methoxybenzenesulfonamide as the substrate
gave compound 2s (57% yield, 70% conversion). 1H NMR (400 MHz,
CDCl3): d=7.68 (d, J=8.4 Hz, 2H), 6.96 (d, J=8.4 Hz, 2H), 6.41 (d, J=
10.0 Hz, 1H), 6.15 (d, J=10.0 Hz, 1H), 4.29–4.24 (m, 1H), 4.18–4.12 (m,
1H), 3.88 (s, 3H), 3.84–3.75 (m, 2H), 1.85 (s, 3H), 1.75 ppm (s, 3H);
13C NMR (100 MHz, DMSO): d=184.8, 163.3, 148.7, 144.0, 133.6, 130.8,
130.0, 127.7, 114.9, 88.3, 85.9, 56.7, 47.5, 14.8, 11.4 ppm; HRMS (ESI+):
m/z calcd for C17H19NO5SNa: 372.0876 [M+Na]+; found: 372.0873.
6-Chloro-4-(4-nitrophenylsulfonyl)-1-oxa-4-azaspiroACHTNUTRGNEUNG[4.5]deca-6,9-dien-8-
one (2m): Following the general procedure by using N-[2-(2-chlorophe-
noxy)ethyl]-4-nitrobenzenesulfonamide as the substrate gave compound
2m (94% yield, 55% conversion). H NMR (400 MHz, CDCl3): d=8.41–
3’-(4-Methoxyphenylsulfonyl)-4H-spiro(naphthalene-1,2’-oxazolidin)-4-
one (2t): Following the general procedure by using 4-methoxy-N-[2-
(naphthalen-1-yloxy)ethyl]benzenesulfonamide as the substrate gave
compound 2t (51% yield, 65% conversion). 1H NMR (400 MHz,
CDCl3): d=8.08 (s, J=7.6 Hz, 1H), 7.46 (t, J=7.6 Hz, 1H), 7.38–7.31 (m,
1H), 7.27 (d, J=7.6 Hz, 2H), 7.21 (d, J=7.6 Hz, 2H), 6.81–6.77 (m, 3H),
6.61 (d, J=10.4 Hz, 1H), 4.43–4.38 (m, 1H), 4.33–4.27 (m, 1H), 3.98–3.93
(m, 1H), 3.84 (s, 3H), 3.81–3.75 ppm (m, 1H); 13C NMR (100 MHz,
DMSO): d=184.0, 163.0, 145.3, 140.6, 133.4, 131.3, 130.6, 129.8, 129.5,
128.5, 128.1, 125.7, 114.7, 87.7, 66.0, 56.2, 47.3 ppm; HRMS (ESI+): m/z
calcd for C19H17NO5SNa: 394.0720 [M+Na]+; found: 394.0748.
1
8.37 (m, 2H), 8.14–8.00 (m, 2H), 6.62 (d, J=9.6 Hz, 1H), 6.47 (d, J=
2.0 Hz, 1H), 6.30 (dd, J=9.6, 2.0 Hz, 1H), 4.46–4.41 (m, 1H), 4.29–4.24
(m, 1H), 3.92–3.87 (m, 1H), 3.81–3.76 ppm (m,1H); 13C NMR (100 MHz,
DMSO): d=183.7, 152.3, 150.6, 144.3, 143.8, 130.1, 129.4, 128.3, 125.3,
87.7, 67.5, 47.9 ppm; HRMS (ESI+): m/z calcd for C14H11ClN2O6SNa:
392.9919 [M+Na]+; found: 392.9922.
6,7-Dimethyl-4-(4-nitrophenylsulfonyl)-1-oxa-4-azaspiroACTHNUTRGENUGN[4.5]deca-6,9-
dien-8-one (2n): Following the general procedure by using N-[2-(2,3-di-
methylphenoxy)ethyl]-4-nitrobenzenesulfonamide as the substrate gave
compound 2n (35% yield, 90% conversion). 1H NMR (400 MHz,
CDCl3): d=8.38–8.35 (m, 2H), 7.95–7.92 (m, 2H), 6.38 (d, J=10.0 Hz,
1H), 6.20 (d, J=10.0 Hz, 1H), 4.35–4.30 (m, 1H), 4.20–4.10 (m, 1H),
3.84–3.81 (m, 2H), 1.89 (s, 3H), 1.75 ppm (s, 3H); 13C NMR (100 MHz,
DMSO): d=184.7, 150.4, 148.0, 144.3, 143.3, 134.0, 129.3, 128.2, 128.1,
125.1, 125.0, 88.8, 66.1, 47.8, 14.8, 11.4 ppm; HRMS (ESI+): m/z calcd
for C16H16N2O6SNa: 387.0621 [M+Na]+; found: 387.0619.
Acknowledgements
This work was financially supported by the National Science Foundation
of China (No. 21072131).
3’-(4-Nitrophenylsulfonyl)-4H-spiro(naphthalene-1,2’-oxazolidin)-4-one
(2o): Following the general procedure by using N-[2-(naphthalen-1-ylox-
y)ethyl]-4-nitrobenzenesulfonamide as the substrate gave compound 2o
Keywords: amidation · ethers · rhodium · rhodium acetate ·
sulfamides · transition-metal catalysis
1
(40% yield, 90% conversion). H NMR (400 MHz, CDCl3): d=8.14–8.10
(m, 3H), 7.50–7.47 (m, 1H), 7.40 (d, J=8.8 Hz, 2H), 7.22–7.18 (m, 1H),
7.01 (d, J=8.0 Hz, 1H), 6.87 (d, J=10.0 Hz, 1H), 6.50 (d, J=10.0 Hz,
1H), 4.49–4.45 (m, 1H), 4.41–4.35 (m, 1H), 4.13–4.08 (m, 1H), 3.80–
3.73 ppm (m, 1H); 13C NMR (100 MHz, DMSO): d=183.9, 150.1, 144.9,
144.2, 139.7, 133.4, 131.3, 130.2, 128.8, 128.6, 128.1, 125.8, 124.8, 88.0,
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Received: July 26, 2011
Revised: October 28, 2011
1082
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