Sulfonoketenimides as key intermediates for the synthesis of N -tosyl-acetoyloxy alkanimines

Article abstract of DOI:10.1055/s-0033-1340836

A copper-catalyzed multicomponent reaction between terminal alkynes, sulfonyl azides, and oximes for the synthesis of N-tosylacetoyloxy alkanimines is reported. This one-pot procedure is carried out in the presence of copper(I) iodide in acetonitrile at room temperature. Georg Thieme Verlag Stuttgart - New York.

Full text of DOI:10.1055/s-0033-1340836

LETTER
▌A
lSetuterlfonoketenimides as Key Intermediates for the Synthesis of N-Tosyl-
acetoyloxy Alkanimines
Synthesis of N-Tosylacetoyloxy Alkanimines
Issa Yavari,* Majid Ghazanfarpour-Darjani, Mohammad J. Bayat, Alaleh Malekafzali
Department of Chemistry, Tarbiat Modares University, PO Box 14115-175, Tehran, Iran
Fax +98(21)82883455; E-mail: yavarisa@modares.ac.ir
Received: 25.01.2013; Accepted: 28.01.2014
Table 1 Optimization of the Reaction Conditions for the Preparation
of 4aa
Abstract: A copper-catalyzed multicomponent reaction between
terminal alkynes, sulfonyl azides, and oximes for the synthesis of N-
tosylacetoyloxy alkanimines is reported. This one-pot procedure is
carried out in the presence of copper(I) iodide in acetonitrile at room
temperature.
Catalyst
Base
Solvent
Yield (%)b
CuI
Et3N
DMF
81
93
32
25
79
–
Key words: alkanimines, terminal alkyne, sulfonyl azide, oxime,
copper iodide
CuI
Et3N
MeCN
CHCl3
THF
CuI
Et3N
CuI
Et3N
Copper-catalyzed multicomponent reactions involving a
ketenimines have served as an effective approach for the
synthesis of compounds with various functional groups.1–
5 This intermediate has attracted much attention due to its
easy formation, relative reactivity, tolerance of procedure,
and its diversity of products.6–8 Recently, we have dis-
closed a novel reactivity of sulfonoketenimides in reac-
tions with amines to give N-sulfonylamidine derivatives.9
CuI
Et2NH
DABCO
Et3N
MeCN
MeCN
MeCN
MeCN
CuI
CuCl
CuBr
70
47
Et3N
a Reaction conditions: 1a (1.0 mmol), 2a (1.0 mmol), 3a (1.2 mmol),
CuI (10 mol%), and Et3N (1.5 mmol) were stirred at 25 °C for 4 h un-
As part of our current studies on the development of new
applications of sulfonoketenimides in organic synthe-
sis,10–12 we report a novel pathway for the synthesis of N-
tosylacetoyloxy alkanimines via a copper(I) iodide cata-
lyzed reaction between sulfonyl azides, 1-alkynes, and
oximes (Scheme 1). Chang and co-workers reported a fac-
ile access to N-sulfonylimidates via the reaction of sulfo-
noketenimides and alcohols.13,14
der argon.
b Isolated yields.
With the optimized reaction conditions in hand a series of
substituted sulfonyl azides, terminal alkynes, and oximes
were subjected to the reaction conditions (Table 2).15
When carbonyl azides were used as the azide source, no
alkanimine was detected in the reaction mixture.
NTs
N-Tosylacetoyloxy alkanimines 4 can be transformed to
the corresponding N-tosylacetamide derivatives. Thus, ef-
ficient conversion of product 4a into 2-phenyl-N-tosyl-
acetamide (5) was achieved by zinc dust and ammonium
chloride in methanol (Scheme 2).16
copper salt
Ph
N
Ph
Ph
TsN3
+
+
Ph
NOH
O
4a
base
solvent
1a
2a
3a
Scheme 1
Initially, the reaction of phenylacetylene, toluenesulfonyl
azide, and benzaldoxime in the presence of triethylamine
and copper(I) iodide (10 mol%) in tetrahydrofuran (2 mL)
at room temperature under argon was studied. After four
hours, product 4a was obtained in 25% yield (Table 1). To
optimize the reaction conditions, a variety of solvents,
copper sources, and bases were considered. The best re-
sults were obtained with triethylamine and copper(I) io-
dide in acetonitrile.
NTs
O
Zn powder
Ph
N
Ph
Ph
O
4a
NHTs
NH4Cl, MeOH
5
Scheme 2
In summary, it is shown that N-tosylacetoyloxy alka-
nimines can be prepared by the coupling of terminal al-
kynes, sulfonyl azides, and oximes in the presence of
copper(I) iodide and triethylamine. The advantages of this
procedure are the use of air-stable, inexpensive copper(I)
iodide catalyst and mild reaction conditions. Transforma-
tion of alkanimine 4a into 2-phenyl-N-tosylacetamide (5)
was achieved by zinc dust and ammonium chloride in
methanol.
SYNLETT 2014, 25, 000A–000B
Advanced online publication: 14.03.2014
0
9
3
6
-
5
2
1
4
1
4
3
7
-
2
0
9
6
DOI: 10.1055/s-0033-1340836; Art ID: ST-2014-D0070-L
© Georg Thieme Verlag Stuttgart · New York

B
I. Yavari et al.
LETTER
(8) Wang, J.; Wang, J. J.; Zhu, Y. X.; Lu, P.; Wang, Y. G. Chem.
Commun. 2011, 47, 3275.
(9) Yavari, I.; Ahmadian, S.; Ghazanfarpur, M.; Solgi, Y.
Tetrahedron Lett. 2011, 52, 668.
(10) Yavari, I.; Nematpour, M.; Sodagar, E. Synlett 2013, 24,
161.
Table 2 Synthesis of N-Tosylacetoyloxy-alkanimines 4
NSO2Ar
CuI, Et3N
R1
N
R2
R1
R2
NOH
ArSO2N3
+
+
O
4
MeCN
r.t., 4 h
1
2
3
(11) Yavari, I.; Nematpour, M. Synlett 2013, 24, 1420.
(12) Yavari, I.; Nematpour, M. Synlett 2013, 24, 165.
(13) Yoo, E. J.; Bae, I.; Cho, S. H.; Han, H.; Chang, S. Org. Lett.
2006, 8, 1347.
(14) Cho, S. H.; Yoo, E. J.; Bae, I.; Chang, S. J. Am. Chem. Soc.
2005, 127, 16046.
(15) Typical Procedure for the Preparation of Products 4a–i
To a stirred solution of alkyne (1, 1.0 mmol), sulfonylazide
(2, 1.0 mmol), and CuI (19 mg, 0.10 mmol) in MeCN (2 mL)
was added Et3N (1.5 mL) under argon at r.t. After 10 min,
oxime (3, 1.2 mmol) was added, and the mixture was stirred
for 4 h. The solvent was removed, the residue treated with of
sat. aq NH4Cl (3 mL) and extracted with EtOAc (3 × 5 mL).
Organic layers were combined, dried over anhydrous
Na2SO4, and concentrated under vacuum. The residue was
purified by chromatography (silica gel, hexane–EtOAc =
2:1) to give 4.
Entry
1–4
R1
Ar
R2
Yield of 4 (%)
1
2
3
4
5
6
7
8
9
a
b
c
d
e
f
Ph
Tol
Tol
Tol
Tol
Tol
Tol
Tol
Ph
Ph
py
87
84
83
79
78
75
76
82
84
Ph
Ph
Me
Ph
py
n-Bu
n-Bu
n-Bu
n-Pr
Tol
Tol
Me
Ph
py
g
h
i
Ph
Me
4-Methyl-N-[(-phenylmethyleneaminooxy)phenyl-
ethylidene]benzenesulfonamide (4a)
Colorless solid, mp 156–158 °C; yield 0.34 g (87%). IR
(KBr): νmax = 3020, 2972, 1569, 1528, 1335, 1128 cm–1. 1H
NMR (500.1 MHz, CDCl3): δ = 2.44 (3 H, s, CH3), 3.60 (2
H, s, CH2), 7.14 (2 H, d, 3J = 8.9 Hz, 2 CH), 7.31–7.48 (8 H,
m, 8 CH), 7.82 (2 H, 3J = 8.5 Hz, 2 CH), 7.88 (2 H, d, 3J =
8.2 Hz, 2 CH), 7.97 (1 H, s, CH). 13C NMR (125.7 MHz,
CDCl3): δ = 21.7 (CH3), 43.8 (CH2), 126.1 (2 CH), 128.1
(CH), 128.5 (2 CH), 128.8 (2 CH), 129.0 (2 CH), 129.3
(CH), 129.4 (2 CH), 129.6 (2 CH), 133.7 (C), 137.5 (C),
141.0 (C), 143.2 (CH), 154.5 (CH), 165.9 (C). MS (EI): m/z
(%) = 392 (5) [M+], 271 (13), 251 (100), 140 (10), 104 (14),
77 (60), 76 (42), 64 (44). Anal. Calcd (%) for C22H20N2O3S
(392.47): C, 67.33; H, 5.14; N, 7.14. Found: C, 67.75; H,
5.19; N, 7.21.
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synlett.SnoIufproig
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iotSrat
maotrin
r
t
References and Notes
(1) Bae, I.; Han, H.; Chang, S. J. Am. Chem. Soc. 2005, 127,
2038.
(2) Yoo, E. J.; Bae, I.; Cho, S. H.; Han, H.; Chang, S. Org. Lett.
2006, 8, 1347.
(3) Cho, S. H.; Chang, S. Angew. Chem. Int. Ed. 2008, 47, 2836.
(4) Yoo, E. J.; Park, S. H.; Lee, S. H.; Chang, S. Org. Lett. 2009,
11, 1155.
(5) Song, W.; Lu, W.; Wang, J.; Lu, P.; Wang, Y. J. Org. Chem.
2010, 75, 3481.
(6) Whiting, M.; Fokin, V. V. Angew. Chem. Int. Ed. 2006, 45,
3157.
(16) (a) Conversion of 4a into 2-Phenyl-N-tosylacetamide (5)
To a stirred solution of 4a (1 mmol) in MeOH (3 mL) was
added NH4Cl (1 mmol) in H2O (1 mL). Then, Zn powder (2
mmol) was added, and the mixture was heated at 70 °C for 2
h. The mixture was cooled, filtered, and the filtrate was
extracted with EtOAc. The organic layer was evaporated and
purified by chromatography (silica gel, hexane–EtOAc =
3:1) to give 5. (b) Cassidy, M. P.; Raushel, J.; Fokin, V. V.
Angew. Chem. Int. Ed. 2006, 45, 3154.
(7) Shang, Y. J.; Ju, K.; He, X. W.; Hu, J. S.; Yu, S. Y.; Zhang,
M.; Liao, K. S.; Wang, L. F.; Zhang, P. J. Org. Chem. 2010,
75, 5743.
Synlett 2014, 25, A–B
© Georg Thieme Verlag Stuttgart · New York