Synthesis of sulfur-containing aryliminophosphoranes

Article abstract of DOI:10.1080/10426500490463556

Stabilized phosphoranes, obtained from the three-component reaction between dialkyl acetylenedicarboxylates and arylsulfonamides in the presence of triphenylphosphine, undergo a smooth intramolecular reaction, in boiling toluene to produce sulfur-containing iminophosphoranes in excellent yields.

Full text of DOI:10.1080/10426500490463556

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Phosphorus, Sulfur, and Silicon and the Related
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SYNTHESIS OF SULFUR-CONTAINING
ARYLIMINOPHOSPHORANES
a
b
a
Issa Yavari , Nader Zabarjad-Shiraz & Hamid R. Bijanzadeh
a
University of Tarbiat Modarres , Tehran, Iran
b
Islamic Azad University, Central Tehran Branch , Tehran, Iran
Published online: 16 Aug 2010.
To cite this article: Issa Yavari , Nader Zabarjad-Shiraz & Hamid R. Bijanzadeh (2004) SYNTHESIS OF SULFUR-
CONTAINING ARYLIMINOPHOSPHORANES, Phosphorus, Sulfur, and Silicon and the Related Elements, 179:7, 1381-1386, DOI:
10.1080/10426500490463556
To link to this article: http://dx.doi.org/10.1080/10426500490463556
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Phosphorus, Sulfur, and Silicon, 179:1381–1386, 2004
Copyright ꢀC Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500490463556
SYNTHESIS OF SULFUR-CONTAINING
ARYLIMINOPHOSPHORANES
a
b
Issa Yavari, Nader Zabarjad-Shiraz,
a
and Hamid R. Bijanzadeh
University of Tarbiat Modarres, Tehran, Iran; and Islamic
Azad University, Central Tehran Branch, Tehran, Iranb
a
(
Received October 14, 2003; accepted November 11, 2003)
Stabilized phosphoranes, obtained from the three-component reaction
between dialkyl acetylenedicarboxylates and arylsulfonamides in the
presence of triphenylphosphine, undergo a smooth intramolecular reac-
tion in boiling toluene to produce sulfur-containing iminophosphoranes
in excellent yields.
Keywords: Acetylenic esters; iminophosphoranes; stable phosphorus
ylides; three-component reaction; triphenylphosphine
Iminophosphoranes, compounds of general structure R3P NR’ with
four-coordinate phosphorus and incorporating a formal phosphorus-
nitrogen double bond, are reactive species, which take part in many
1
−5
valuable reactions in organic synthesis.
Iminophosphoranes were
6
first reported by Staudinger and Meyer in 1919 but virtually no addi-
tional chemistry was reported until the early 1960s. Much chemistry
has been discovered in the last decades with numerous applications
to organic synthesis.1 Several methods have been developed for the
preparation of iminophosphoranes, although the general procedure is
the reaction of triphenylphosphine with azide compounds.1−10 Reaction
of triarylphosphines with dialkyl acetylenedicarboxylates, and on occa-
−5
1
1,12
sion, other acetylenic systems have been discussed.
We recently
described the synthesis of sulfur-containing phosphorus ylides 3 using
the three-component reaction of dialkyl acetylenedicarboxylates 1 and
1
3
arylsulfonamides 2 in the presence of triphenylphosphine. Herein we
report that these stable phosphoranes undergo a smooth transforma-
tion in boiling toluene to produce sulfur-containing iminophosphoranes
4
in excellent yields (see Scheme 1).
Address correspondence to Issa Yavari, Department of Chemistry, University of Tar-
biat Modarres, P.O. Box 14115-175, Tehran, Iran. E-mail: isayavar@yahoo.com
1
381

1
382
I. Yavari et al.
SCHEME 1
RESULTS AND DISCUSSION
The reaction of arylsulfonamides with dialkyl acetylenedicarboxylates
in the presence of triphenylphosphine proceeded spontaneously at room
temperature in ethyl acetate, and was finished within 3 hours. The
1
13
H and C NMR spectra of the crude product clearly indicated the
formation of phosphoranes 3. Any other product could not be detected
by NMR spectroscopy.
1
13
31
The H, C, and P NMR spectra of ylides 3 are consistent with the
1
3
31
presence of two rotational isomers (Scheme 2). During dynamic
NMR study of these rotational isomers, a sharp single peak at about
4.6 ppm started to grow as the temperature was increased. In or-
P
1
der to identify this new product, phosphorus ylides 3 were refluxed
in toluene. The reaction proceeded cleanly and produced iminophos-
phoranes 4 together with dialkyl fumarates and/or dialkyl maleates 5
(
Scheme 1). Structure 4 was assigned to the isolated products on the
1
13
31
basis of their elemental analyses, IR, H, C, and P NMR and mass
spectral data. The mass spectra of iminophosphoranes 4 confirm their
molecular weights.

Aryliminophosphoranes
1383
SCHEME 2
Although we have not established the mechanism of the formation of
iminophosphoranes 4 from ylides 3 in an experimental manner, a possi-
ble mechanism is indicated in Scheme 3. It is reasonable to assume that
in boiling toluene, the NH-proton shifts to the ylenic carbon and forms
the phosphorus betaine 6. This betaine can be in equilibrium with the
azaphosphetane 7. Iminophosphorane 4 is formed from fragmentation
of the azaphosphetane 7. Formation of dialkyl fumarates and/or dialkyl
maleates 5 confirms the proposed mechanism (Scheme 3).
SCHEME 3
In summary, the present synthesis of iminophosphoranes comple-
ments older methods and offers significant advantages for the synthesis
of iminophosphoranes from sulphonamides. The present method carries
the advantage that, not only is the reaction performed under neutral
conditions, but also that the substances can be mixed without any mod-
ification. The procedure described here may be an acceptable alterna-
tive method for the preparation of iminophosphoranes with variable
functionalities.
EXPERIMENTAL
Melting points were measured on an Electrothermal 9100 apparatus.
Elemental analyses for C, H, and N were performed using a Heraeus
CHN-O-Rapid analyzer. These data were in good agreement with the

1
384
I. Yavari et al.
calculated ones. IR spectra were measured on a Shimadzu IR 460 spec-
1
13
31
trometer. H, C, and P NMR spectra were measured with BRUKER
DRX-500 AVANCE spectrometer at 500.1, 125.8, and 202.4 MHz, re-
spectively. The mass spectra were recorded on a Finnigan-Matt 8430
mass spectrometer operating at an ionization potential of 70 eV. Triph-
enylphosphine and dialkyl acetylenedicarboxylates were obtained from
1
3
Fluka (Buchs, Switzerland). Phosphoranes 3a–3f have been reported.
Dimethyl 2-(4-ethylbenzenesulfonylamino)-3-(triphenylphos-
phanylidene)-succinate 3g was prepared according to the previous
1
3
◦
report. White powder, 0.92 g, yield 80%, m.p.: 172–174 C. IR (KBr)
(
−1
νmax, cm ): 3350 (N H), 1738 (C O), 1609 (C C). Anal. Calcd. for
C32H32NO6PS (589.6): C, 65.18; H, 5.47; N, 2.38%. Found: C, 65.3; H,
5
.3; N, 2.2%.
1
Major isomer 3g-(Z) (65%), H NMR (500.1 MHz, CDCl3): δ 1.20 (3H,t,
3
3
JHH = 7.6 Hz, CH3), 2.65 (2H, q, JHH = 7.6 Hz, CH2), 3.11 and 3.49
3
3
(
6 H, 2 s, 2 OCH3), 3.98 (1H, dd, JHH = 9.3 Hz, JPH = 15.6 Hz, CH),
3
13
6
.67 (1H, br d, JHH = 9 Hz, NH),7.3–7.7 (19H, m, 3 C6H5 and C6H4). C
1
NMR (125.7 MHz, CDCl3): δ 15.2 (CH2CH3) 28.8 (CH2), 43.6 (d, JPC =
2
1
27.1 Hz, P C C), 49.5 and 52.6 (2 OCH3), 56.0 (d, JPC = 17.3 Hz,
1
N CH), 126.4 (d, JPC = 92.6 Hz, P Cipso), 129.0–134.0 (CH arom),
2
1
38.88 (C CH3), 142.88 (C S), 170.4 (d, JPC = 12.2 Hz, P C C O),
3
31
1
73.1 (d, JPC = 7.2 Hz, C O). P NMR (202.4 MHz,CDCl3): δ 21.78
+
(
Ph3P C).
1
Minor isomer 3g-(E) (35%), H NMR (500.1 MHz, CDCl3): δ 1.28 (3H,t,
3
3
JHH = 7.6 Hz, CH3), 2.65 (2H,q, JHH = 7.6 Hz, CH2), 3.49 and 3.54
3
3
(
(
6H, 2 s, 2 OCH3), 3.94 (1H, dd, JHH = 9.3 Hz, JPH = 13.3 Hz, CH), 6.02
3
13
1H, br d, JHH = 9 Hz, NH),7.3–7.7 (19H, m, 3 C6H5 and C6H4).
C
1
NMR (125.7 MHz, CDCl3): δ 14.8 (CH2CH3) 25.3 (CH2), 44.2 (d, JPC =
2
1
35.9 Hz, P C C), 50.5 and 52.7 (2 OCH3), 55.2 (d, JPC = 17.2 Hz,
1
N CH), 125.8 (d, JPC = 92.4 Hz, P Cipso), 129.0–134.0 (CH arom),
2
1
38.52 (C CH3), 143.05 (C S),170.3 (d, JPC = 16.7 Hz, P C C O),
3
31
1
73.1 (d, JPC = 7.2 Hz, C O). P NMR (202.4 MHz,CDCl3): δ 22.73
+
(
Ph3P C).
Preparation of P,P,P-Triphenyl-N-phenylsulfonylphos-
phine Imide 4a
General Procedure
The process for preparation of 4a is described as an example. A mag-
netically stirred mixture of 0.56 g phosphorane 3a (1 mmol) in 30 mL
toluene was refluxed for 12 h. The solvent was removed under reduced
pressure and the solid residue was washed with 2 × 5 mL cold diethyl
ether and the product was obtained as a white powder, 0.40 g, yield 98%,

Aryliminophosphoranes
1385
◦
−1
m.p.: 156–158 C. IR (KBr) (νmax, cm ): 3050, 1575, 1469, 1429. Anal.
Calcd. for C24H20NO2PS (417.5): C, 69.05; H, 4.83; N, 3.36%. Found: C,
1
6
9.15; H, 4.71; N, 3.45%. H NMR (500.1 MHz, CDCl3): [7.23 (2H, dd,
3
3
3
JHH = 7.2 Hz, JHH = 7.9 Hz, 2 CHmeta), 7.32 (1H, t, JHH = 7.2 Hz,
3
CHpara), 7.65 (2H, d, JHH = 7.9 Hz, CHortho) (for S Ph)], 7.48 (6H, ddd,
3
3
3
4
JHH = 7.9 Hz, JHH = 7.2 Hz, JPH = 2.2 Hz, 6CHmeta), 7.60 (3H, t,
JHH = 7.2 Hz, 3CHpara), 7.78 (6H, dd, JHH = 7.9 Hz, JPH = 12.8 Hz,
CHortho). C NMR (125.7 MHz, CDCl3): 125.7, 128.1, 130.0, 146.1 (for
3
3
1
3
6
1
3
S Ph), 127.2 (d, JPH = 104 Hz, P C), 128.8 (d, JPH = 13 Hz, Cortho),
32.9 (d, JPH = 3 Hz, Cpara), 133.1 (d, JPH = 11 Hz, Cmeta). P NMR
202.4 MHz,CDCl3): δ 14.96 (Ph3P N).
5
4
31
1
(
P,P,P-Triphenyl-N-(toluene-4-sulfonyl)phosphine
Imide 4b
◦
White crystals, 0.42 g, yield 97%, m.p.: 165–167 C. IR (KBr) (νmax,
−1
cm ): 3025, 1471, 1422. Anal. Calcd. for C25H22NO2PS (431.5): C,
9.59; H, 5.14; N, 3.45%. Found: C, 69.40; H, 5.20; N, 3.09%. H NMR
500.1 MHz, CDCl3): δ 2.28 (3H, s, CH3), 6.99 (2H, d, JHH=7.8 Hz,
1
6
(
3
3
3
2
7
7
CHortho), 7.49 (2H, d, JHH = 7.8 Hz, 2CHmeta), 7.44 (6H, ddd, JHH =
4
3
3
.7 Hz, JPH = 3.0 Hz, JHH = 7.3 Hz, 6CHmeta), 7.56 (3H, d, JHH =
3
3
.3 Hz, 3CHpara), 7.72 (6H, dd, JPH = 12.9 Hz, JHH = 7.7 Hz, 6CHortho).
1
3
C NMR (125.7 MHz, CDCl3): δ 21.3 (CH3), 125.7, 128.8, 140.0
1
(
C CH3) and 143.5 (C-S) (for S-C6H4-), 127.7 (d, JPH = 104 Hz, P C),
3
5
1
28.8 (d, JPH = 12 Hz, Cortho), 133.1 (d, JPH = 3 Hz, P Cpara), 132.8 (d,
4
31
JPH = 11 Hz, Cmeta). P NMR (202.4 MHz,CDCl3): δ 14.62 (Ph3P N).
P,P,P-Triphenyl-N-(4-ethylbenzenesulfonyl)phosphine
Imide 4c
◦
Colorless crystals, 0.42 g, yield 98%, m.p.: 171–173 C. IR (KBr) (νmax,
−1
cm ): 3030, 1476, 1428. Anal. Calcd. for C26H24NO2PS (445.5): C,
0.09; H, 5.43; N, 3.14%. Found: C, 70.2; H, 5.3; N, 3.0%. H NMR
1
7
3
(
500.1 MHz, CDCl3): δ 1.18 (3H, t, JHH = 7.5 Hz, CH3), 2.58 (2H, q,
3
3
3
3
JHH = 7.5 Hz, CH2), 6.99 (2H, d, JHH = 7.8 Hz, 2CHortho), 7.49 (2H, d,
3
4
JHH = 7.8 Hz, 2CHmeta), 7.44 (6H, ddd, JHH = 7.7 Hz, JPH = 3.0 Hz,
3
JHH = 7.3 Hz, 6CHmeta), 7.56 (3H, d, JHH = 7.3 Hz, 3CHpara), 7.72 (6H,
3
3
13
dd, JPH = 12.9 Hz, JHH = 7.7 Hz, 6CHortho). C NMR (125.7 MHz,
CDCl3): δ 15.5 (CH3), 28.7 (CH2), 125.7, 128.8, 143.6 (C CH2) and
1
1
46.7 (C S) (for S C6H4 ), 127.7 (d, JPH = 104 Hz, P C), 128.8 (d,
3
5
4
JPH = 12 Hz, Cortho), 133.1 (d, JPH = 3 Hz, P Cpara), 132.8 (d, JPH =
1 Hz, Cmeta). P NMR (202.4 MHz,CDCl3): δ 14.72 (Ph3P N).
3
1
1

1
386
I. Yavari et al.
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[
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