Regioselective synthesis of (E)-3-[2-(arylmethylene)-1-(arylsulfonyl) hydrazino]-2-propenoates via the reaction of arylsulfonyl hydrazones and alkyl propiolates in the presence of triphenylphosphine

Article abstract of DOI:10.1016/j.tetlet.2012.07.055

A regioselective method for the synthesis of (E)-3-[2-(arylmethylene)-1- (arylsulfonyl)hydrazino]-2-propenoates is described. The reaction takes place between arylsulfonyl hydrazones and alkyl propiolates in the presence of triphenylphosphine as the catalyst.

Full text of DOI:10.1016/j.tetlet.2012.07.055

Tetrahedron Letters 53 (2012) 5141–5143
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Tetrahedron Letters
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Regioselective synthesis of (E)-3-[2-(arylmethylene)-1-(arylsulfonyl)hydrazino]-
2-propenoates via the reaction of arylsulfonyl hydrazones and alkyl propiolates
in the presence of triphenylphosphine
⇑
Seyed Abolghasem Hashemi
Chemistry Department, Islamic Azad University, Bushehr Branch, PO Box 7519619555, Bushehr, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
A regioselective method for the synthesis of (E)-3-[2-(arylmethylene)-1-(arylsulfonyl)hydrazino]-2-pro-
penoates is described. The reaction takes place between arylsulfonyl hydrazones and alkyl propiolates in
the presence of triphenylphosphine as the catalyst.
Received 8 January 2012
Revised 10 June 2012
Accepted 12 July 2012
Available online 20 July 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Regioselective reaction
Arylsulfonyl hydrazone
Triphenylphosphine
Alkyl propiolate
Hydrazones are a very interesting class of compounds that have
various applications in organic synthesis as nucleophiles and elec-
trophiles.1–4 Their ease of preparation, tendency toward crystallin-
ity, and increased hydrolytic stability relative to imines are all the
desirable characteristics of hydrazones. In addition, sulfonyl hydra-
zones are versatile synthetic intermediates that have been used as
an in situ source of diazo compounds in different types of
metal-catalyzed and metal-free reactions, which has significantly
improved their applications.5–12 Despite these positive traits,
hydrazones have been under-studied and much of their basic
chemistry remains unexplored. Our interest in hydrazones was as
nucleophilic partners in Michael reactions.13,14 There are some
examples in the literature of aza-Michael additions.15–19 Alkyl pro-
piolates should be particularly prone to undergo such Michael
additions. In this context, the stereoselective synthesis of multi-
functional alkenes has been reported from alkyl propiolates.20 In
addition, olefin synthesis by means of transition metal catalysis
has shown a significant progress.21,22 We were intrigued by the
possibility of intermolecular trapping of the 1,3-zwitterionic
intermediate23–25 generated from triphenylphosphine and alkyl
propiolates with sulfonyl hydrazone compounds.26 Triphenylphos-
phine-catalyzed reactions of terminal alkyne substrates 2 with
arylsulfonyl hydrazones 127,4,28 at room temperature gave substi-
tuted (E)-3-[2-(arylmethylene)-1-(arylsulfonyl)hydrazino]-2-pro-
penoates 3a–3j, stereoselectively, in high yields. The results are
listed in Scheme 1 and no Z-isomers of products 3 were detected.
The products were characterized on the basis of spectroscopic
data. The 1H NMR (400 MHz) spectrum of 3a displayed two singlets
at d 2.43 and d 3.88 characteristic of methyl and methoxy groups,
while the olefinic protons were observed as two separate doublets
at d 5.37 and d 8.12 (3J = 13.6 Hz). The aromatic protons appeared
between d 7.32 and 7.78, whilst the imine proton was present as
a sharp singlet at d 8.69. The values of the coupling constants for
the ethylenic protons indicated that the 2-propenoates 3 existed
exclusively in the E-configuration. The 13C NMR spectrum of 3a
exhibited fourteen signals, the most relevant being displayed at d
101.9 and d 141.7 due to the olefinic carbons. The carbomethoxy
and imine resonances were discernible at d 167.2 and d 169.3,
respectively. In the IR spectrum of 3a, the absorption band due
to the ester carbonyl was present at 1702 cmÀ1. The absorptions
at 1342 and 1148 cmÀ1 were attributed to sulfonyl absorptions.
The mass spectrum of this compound (3a) displayed a molecular
ion peak at m/z = 358. The relative stereochemistry of 3a was
established by single crystal X-ray analysis (Fig. 1).29
Although the reaction mechanism has not yet been confirmed
with sufficient evidence, a possible explanation is proposed in
Scheme 2. On the basis of the well established chemistry of triva-
lent phosphorus nucleophiles, it is reasonable to assume that the
products result from initial addition of triphenylphosphine to alkyl
propiolate 2 and subsequent protonation of the 1:1 adduct by the
NH- acid 1. Next, the positively charged ion 5 is attacked by the
nitrogen atom of conjugate base intermediate 6 to form 7, which
in turn is converted into product 3 by elimination of PPh3.
⇑
Tel.: +98 7715682305; fax: +98 7715683700.
E-mail address: abolghasem.hashemy@gmail.com
0040-4039/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2012.07.055

5142
S. A. Hashemi / Tetrahedron Letters 53 (2012) 5141–5143
H
O
O
O
O
O
O
S
Ar2
N
OR
PPh3
Ar1
N
S
H
+
N
Ar2
CH2Cl2, r.t., 20 h
H
N
H
OR
H
H
Ar1
2
1
3a-j
Ar1
Product
3a
Ar2
4-MeC6H4
R
(%)
Yield
75
Ph
Me
Et
4-MeC
Ph
6H4
3b
3c
4-ClC6H4
80
77
80
75
Me
4-ClC6H4
Ph
Et
4-ClC6H4
4-MeC6H4
3d
3e
3f
4-MeC6H4
Me
4-MeC6H4
4-MeC6H4
Ph
Et
70
85
Me
3g
3h
3i
Ph
Ph
Ph
Et
80
Me
4-ClC6H4
Ph
4-MeC6H4
85
70
3j
4-MeC6H4 Et
Scheme 1.
2-propenoates using a one-pot procedure. These products contain-
ing important functional groups can be manipulated via a variety
of transformations. Thus, this procedure may provide a new ap-
proach for the preparation of multifunctional alkenes in a stereose-
lective manner.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.tetlet.2012.07.
055.
References and Notes
1. Cacch, S.; La Torre, F.; Misiti, D. Synthesis 1997, 30.
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446.
5. Fulton, J. R.; Aggarwal, V. K.; de Vicente, J. Eur. J. Org. Chem. 2005, 1479.
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2535.
7. Aller, E.; Brawn, D. S.; Cox, G. G.; Miller, D. J.; Moody, C. J. J. Org. Chem. 1995, 60,
4449.
8. Aggarwal, V. K.; de Vicent, J.; Bonnert, R. V. Org. Lett. 2001, 3, 2785.
9. Aggarwal, V. K.; Bae, I.; Lee, H. Y.; Richardson, J.; Williams, D. T. Angew. Chem.,
Int. Ed. 2003, 42, 3274.
10. Barluenga, J.; Tomas-Gamasa, M.; Aznar, F.; Valdes, C. Nat. Chem. 2009, 1, 443.
11. Aggarwal, V. K.; Alonso, E.; Fang, G. Y.; Ferrara, M.; Hynd, G.; Porcelloni, M.
Angew. Chem., Int. Ed. 2001, 40, 1433.
Figure 1. X-ray crystal structure (ORTEP) of 3a.
12. Barluenga, J.; Tomas-Gamasa, M.; Aznar, F.; Valdes, C. Angew. Chem., Int. Ed.
2010, 49, 4993.
13. Lassaletta, M. J.; Fernandenz, E.; Martin-Zamora, E.; Monge, D.; Herrera, P. R.
Org. Lett. 2007, 9, 3303.
14. Lassaletta, M. J.; Enders, R.; Fernandez, R.; Prieto, A.; Vazquez, J. Chem. Commun.
2002, 498.
O
O
H
OR
H
1
PPh3
+
H
CHCO2R
+
OR
Ph3P
Ph3P
4
2
5
H
O
15. Wabnitz, T. C.; Yu, J. Q.; Spencer, J. B. Chem. Eur. J. 2004, 10, 484.
16. Wabnitz, T. C.; Spencer, J. B. Org. Lett. 2003, 5, 2141.
17. Wu, D.; Liu, Y.; He, C.; Chung, T.; Goh, S. Macromolecules 2004, 37, 6763.
18. Vedejs, E.; Gingras, M. J. Am. Chem. Soc. 1994, 116, 579.
19. Liu, M.; Sibi, M. P. Tetrahedron 2002, 58, 7991.
20. Yavari, I.; Hazeri, N.; Maghsoodlou, T. M.; Souri, S. J. Mol. Cat. 2007, 264, 313.
21. Negishi, E. I., Demeijere, A., Eds.Handbook of Organopalladium Chemistry for
Organic Synthesis; Wiley: New York, 2002; Vol. 2,.
O
O
O
O
O
PPh3
O
O
S
S
Ar2
H
N
N
Ar1
N
S
Ar2
N
-PPh3
OR
OR
N
Ar2
H
H
H
N
H
H
6
3
Ar1
Ar1
7
Scheme 2.
22. (a) Schrock, R. R.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2003, 42, 4592; (b)
Gioukalakis, G. C.; Grubbs, R. H. Chem. Rev. 2010, 110, 1746.
23. Maryanoff, B. E.; Reitz, A. B. Chem. Rev. 1989, 89, 863.
24. Arduago, A. J.; Stewart, C. A. Chem. Rev. 1994, 94, 1215.
In summary, we have described a novel three-component reac-
tion yielding (E)-3-[2-(arylmethylene)-1-(arylsulfonyl)hydrazino]-

S. A. Hashemi / Tetrahedron Letters 53 (2012) 5141–5143
5143
25. Kolodiazhynyi, O. I. Russ. Chem. Rev. 1997, 66, 225.
7.55 (1H, tt, 3J = 7.3 Hz, 4J = 1.4 Hz, CH), 7.66 (2H, d, 3J = 7.8 Hz, 2CH), 7.78 (2H,
d, 3J = 7.3 Hz, 2CH), 8.12 (1H, d, 3J = 13.6 Hz, CH), 8.69 (1H, s, CH@N). 13C NMR
(100.6 MHz, CDCl3): d = 21.6 (Me), 51.3 (MeO), 101.9 (CH), 127.9 (2CH), 128.9
(2CH), 129.1 (2CH), 129.9 (2CH), 132.2 (C), 132.8 (CH), 133.7 (C), 141.7 (CH),
145.3 (C), 167.2 (C@O), 169.3 (CH@N). EI–MS: 358 (M+, 5), 205 (100), 155 (63),
91(95), 65 (46). Anal. Calcd for C18H18N2O4S (358.41): C 60.32, H 5.06, N 7.82.
Found: C 60.68, H 4.89, N 7.69.
26. General procedure for the synthesis of compounds 3: a solution of alkyl propiolate
2 (1 mmol) in dry CH2Cl2 (2 ml) was added dropwise over a period of 5 min to a
suspension of PPh3 (1 mmol) and arylsulfonyl hydrazone 1 (1 mmol) in CH2Cl2
(5 ml) at À5 to 0 °C. This mixture was held at this temperature for 10 min, and
then stirred for 20 h at room temperature. The organic solvent was evaporated
under reduced pressure. The resulting residue was purified by silica gel column
chromatography (6:1 hexane/EtOAc) and recrystallized from Et2O to afford a
27. Berdinskii, E. I.; Posyagina, Y. S.; Orlova, L. D.; Lyadova, A. A. Zh. Org. Khim.
1990, 26, 336.
28. Zhao, G. I.; Shi, M. Tetrahedron 2005, 61, 7277.
29. Single crystal X-ray structure data for 3a have been deposited at the Cambridge
Crystallographic Data Centre and allocated the deposition number CCDC
885079.
crystalline
(phenylmethylene)hydrazine}-2-propenoate (3a): White powder, yield: 0.26 g
(75%), m.p. 127 °C. IR (KBr) (
max/cmÀ1): 1702, 1621, 1342, 1148, 823, 570. 1H
product.
Methyl
(E)-3-{1-[(4-methylphenyl)sulfonyl]-2-
m
NMR (400.1 MHz, CDCl3): d = 2.43 (3H, s, Me), 3.88 (3H, s, MeO), 5.37 (1H, d,
3J = 13.6 Hz, CH), 7.32 (2H, d, 3J = 7.8 Hz, 2CH), 7.45 (2H, t, 3J = 7.5 Hz, 2CH),