Unexpected synthesis of novel O -ethyl- P -aryl- N -(thiophen-2-yl) phosphonamidothioates from ethyl 2-aminothiophene- 3-carboxylates and Lawesson's reagent

Article abstract of DOI:10.1080/17415993.2013.815750

The reaction of ethyl 2-aminothiophene-3-carboxylates with a stoichiometric amount of Lawesson's reagent (LR) gave novel O-ethyl-P-aryl-N-(thiophen-2-yl) phosphonamidothioate derivatives rather than the expected thienothiazaphosphorines. A possible reaction mechanism, involving a carbonyl sulfide extrusion, is proposed.

Full text of DOI:10.1080/17415993.2013.815750

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Unexpected synthesis of novel
O-ethyl-P-aryl-N-(thiophen-2-yl)
phosphonamidothioates from ethyl 2-
aminothiophene- 3-carboxylates and
Lawesson's reagent
Khaoula Khalladi a & Soufiane Touil a
a Laboratory of Heteroatom Organic Chemistry, Department of
Chemistry, Faculty of Sciences of Bizerta , University of Carthage ,
7021-Jarzouna , Tunisia
Published online: 26 Jul 2013.
To cite this article: Khaoula Khalladi & Soufiane Touil , Journal of Sulfur Chemistry (2013):
Unexpected synthesis of novel O-ethyl-P-aryl-N-(thiophen-2-yl) phosphonamidothioates from
ethyl 2-aminothiophene- 3-carboxylates and Lawesson's reagent, Journal of Sulfur Chemistry, DOI:
10.1080/17415993.2013.815750
To link to this article: http://dx.doi.org/10.1080/17415993.2013.815750
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Journal of Sulfur Chemistry, 2013
http://dx.doi.org/10.1080/17415993.2013.815750
Unexpected synthesis of novel O-ethyl-P-aryl-N-(thiophen-2-yl)
phosphonamidothioates from ethyl 2-aminothiophene-
3-carboxylates and Lawesson’s reagent
Khaoula Khalladi and Soufiane Touil*
Laboratory of Heteroatom Organic Chemistry, Department of Chemistry, Faculty of Sciences of Bizerta,
University of Carthage, 7021-Jarzouna, Tunisia
(Received 25 April 2013; final version received 12 June 2013)
The reaction of ethyl 2-aminothiophene-3-carboxylates with a stoichiometric amount of Lawesson’s
reagent (LR) gave novel O-ethyl-P-aryl-N-(thiophen-2-yl) phosphonamidothioate derivatives rather than
the expected thienothiazaphosphorines. A possible reaction mechanism, involving a carbonyl sulfide
extrusion, is proposed.
O
R1
LR (0.5 mol-equiv.)
S
S
P
toluene, reflux
N
R2
Ar
O
S
H
R1
OEt
R2
NH2
S
R1
LR (0.5 mol-equiv.)
toluene, reflux
S
P
Ar
OEt
N
R2
S
H
S
Ar
S
S
,
Ar:
P
P
LR:
OMe
Ar
S
Keywords: thiophenes; Lawesson’s reagent; thiophosphonamides; phosphonamidothioates; carbonyl
sulfide extrusion
1. Introduction
2,4-Bis(p-methoxyphenyl)-1,3,2,4-dithiaphosphetane-2,4-disulfide [Lawesson’s reagent (LR)]
is widely used in heterocyclic synthesis, particularly for the construction of six-membered
heterocyclic rings by reaction with 1,4-dipolar reagents.[1–4] In this area, we have previously
*Corresponding author. Email: soufiane.touil@fsb.rnu.tn
© 2013 Taylor & Francis

2
K. Khalladi and S. Touil
shown that 2-amino-3-cyanothiophenes react with LR, in stoichiometric ratio to give novel fused
thienodiazaphosphorine derivatives.[5] We report, in the present investigation, the extension of
this reaction to ethyl 2-aminothiophene-3-carboxylates. Our initial objective was to access new
thienothiazaphosphorine derivatives. Contrary to our expectation, the reaction did not stop at
this stage but gave the novel O-ethyl-P-aryl-N-(thiophen-2-yl) phosphonamidothioates 2, via a
carbonyl sulfide extrusion.
It is interesting to note here that thiophene derivatives are an important class of compounds
in medicinal chemistry with a wide range of biological properties, including anticancer,[6, 7]
antimicrobial,[8–10] antiviral,[11] anti-inflammatory,[12, 13] and antifungal [14] activities. On
the other hand, compounds bearing the thiophosphonamide functionality are known to exhibit
antimalarial [15] and antitumor [16] activities. Some of these compounds are also known for their
applications in agrochemistry as pesticide agents.[17]
2. Results and discussion
The starting ethyl 2-aminothiophene-3-carboxylates 1 were easily prepared according to the
reported Gewald synthetic procedure.[18] Esters 1e and 1g are new compounds and their struc-
tures were established by examination of their IR, 1H, and 13C NMR data, whereas compounds
1a–d, 1f, and 1h have been identified by comparison of their spectroscopic data with those of the
literature.[18]
It was found that reaction of compounds 1 with a stoichiometric amount of LR (0.5 mol-equiv.),
performed in refluxing toluene, for 72 h, led to O-ethyl-P-aryl-N-(thiophen-2-yl) phosphonami-
dothioates 2 rather than the expected thienothiazaphosphorine derivatives A (Scheme 1).
O
R1
LR (0.5 mol-equiv.)
S
S
P
toluene, reflux
N
R2
Ar
O
S
H
R1
OEt
A
R2
NH2
S
R1
1
LR (0.5 mol-equiv.)
toluene, reflux
S
P
Ar
OEt
N
R2
S
H
2
S
Ar
S
S
,
Ar:
P
P
LR:
OMe
Ar
S
Scheme 1. Synthesis of 2-thiophosphoramidothiophenes 2.
A plausible mechanism for the formation of compounds 2 is depicted in Scheme 2. It is believed
that the reaction begins with a nucleophilic attack of the NH2 group on LR giving rise to the inter-
mediate I. A subsequent intramolecular cyclization, through the nucleophilic attack of the sulfur
atom on the ester function, generates the thiazaphosphorine intermediate A. The later recombines
with ethanol to yield, after extrusion of carbonyl sulfide, the 2-thiophosphonamidothiophene 2 as
final product.

Journal of Sulfur Chemistry
3
S
S
S
S
S
Ar
S
2
Ar
P
P
P
LR:
Ar
O
O
O
S
Et
Et
_
SH
R1
R1
R1
R2
C
Ar
P
O
S
O
S
Ar
+
EtOH
P
_
NH2
R2
R2
N
N
P
S
Ar
S
S
S
S
H
H
1
I
A
O
O
H
R1
R1
R1
H
S Ar
P
S
S
O
Et
Ar
Ar
- COS
R2
N
H
P
R2
N
R2
N
P
S
S
S
S
OEt
S
H
OEt
H
H
2
Scheme 2. Proposed mechanism for the formation of compounds 2.
Table 1. Substrate scope studies.
Entry
R1
R2
Product
Yield (%)a
1
2
3
4
5
6
7
8
(CH2)4
(CH2)3
2a
2b
2c
2d
2e
2f
74
66
48
54
62
70
68
63
Ph
CH3
Ph-CH2
CH3
CH3
CH3
H
CH3
Ph
H
Ph-CH2
Ph
2g
2h
aIsolated yield.
To the best of our knowledge, very little has appeared in the literature concerning the carbonyl
sulfide extrusion.[19, 20] Thus, by developing new synthetic pathways involving such transfor-
mations, we would be able to obtain a better perspective on the mechanistic insights of these rare
extrusions.
It is important to note that our attempts to stop the reaction at the stage of the thienothiaza-
phosphorine derivative A, by reducing the reaction time and lowering the temperature, failed. In
all cases, the reaction furnished compounds 2 but in lower yields.
The scope of the reaction was assessed with a range of ethyl 2-aminothiophene-3-carboxylates
with various substituents and different ring sizes. All substrates reacted to give O-ethyl-P-aryl-
N-(thiophen-2-yl) phosphonamidothioates 2, in moderate to good yields (Table 1).
The formation of compounds 2 was confirmed by IR, NMR (1H, 31P, 13C) and mass spectral
data. The IR spectra revealed the presence of absorption bands toward 700 and 3300 cm−1 corre-
1
=
−
sponding, respectively, to the P S and N H vibrators. The H NMR spectrum of each compound
−
2 showed, in particular, a doublet around 10 ppm, ascribable to the N H proton. Such a doublet is
characteristic for the coupling with phosphorus with a 2JPH coupling constant of about 9–12 Hz.
We also observed a singlet at 3.7 ppm assignable to the methoxy protons introduced by LR. The
ethoxy group on the phosphorus atom gives a triplet and quartet at 1 and 4 ppm, respectively.
The 31P NMR shift recorded for compounds 2 was δ = 69–76 ppm which is consistent with the
thiophosphoryl chemical shift values. The 13C NMR spectra display the characteristic signals of
all carbon atoms and particularly those corresponding to the thiophene ring. Of particular note

4
K. Khalladi and S. Touil
are the carbon atoms of the ethoxy group which resonate as two doublets at 16 and 60 ppm. The
structures of the compounds 2 were supported additionally by the mass spectra which showed
the correct molecular ion peaks. The different fragments in the EI-MS spectrum of compound
2a are described in Scheme 3. In addition to the molecular ion which is present at m/z 367, we
also observed a fragment at m/z 321 corresponding to the loss of EtOH. The α-cleavage with
respect to the oxygen atom gave the fragment at m/z 215 which lost ethylene to give the base ion
at m/z 187.
.
+
.
+
S
P
S
Ar
N
H
N
P
- EtOH
S
S
OEt
Ar
m/z (%) = 367 (58)
m/z (%) = 321 (16)
S
P
S
P
S
H
Ar
N
H
P
- CH2=CH2
S
CH2
.
Ar
H
Ar
O
+
C
H
O
+
H
+
-
O-CH2-CH3
.
m/z (%) = 187 (100)
NH
S
m/z (%) = 215 (39)
Scheme 3. Main fragments in the EI-MS spectrum of compound 2a.
In conclusion, we have shown in the present investigation that the reaction of ethyl
2-aminothiophene-3-carboxylates with a stoichiometric amount of LR did not stop at the stage
of the thienothiazaphosphorine derivatives but gave the novel O-ethyl-P-aryl-N-(thiophen-2-yl)
phosphonamidothioates, via a carbonyl sulfide extrusion.
3. Experimental
1H, 31P, and 13C NMR spectra were recorded with CDCl3 as the solvent, on a Bruker-300 spec-
trometer. The chemical shifts are reported in ppm relative to TMS (internal reference) for 1H and
13C NMR and relative to 85% H3PO4 (external reference) for 31P NMR. The coupling constants
are reported in Hz. For the 1H NMR, the multiplicities of signals are indicated by the following
abbreviations: s: singlet, d: doublet, t: triplet, q: quartet, quint: quintet, and m: multiplet. Mass
spectra were determined on an Agilent 5975B spectrometer, under electronic impact (EI) condi-
tions. IR spectra were recorded on a Nicolet IR200 spectrometer. The progress of the reactions
was monitored by TLC. Purification of products was performed by column chromatography using
silica gel 60 (Fluka).
3.1. Synthesis of ethyl 2-aminothiophene-3-carboxylates (1)
The starting esters 1 were prepared according to the reported Gewald synthetic procedure.[18]
Ethyl 2-amino-4-benzyl-5-phenylthiophene-3-carboxylate (1e). Yellow oil; Yield (%) = 78;
3
1H NMR (300 MHz, CDCl3): δ = 1.32 (t, 3H, JHH = 6.0 Hz, CH3 CH2 O); 4.11 (q, 2H,
−
−
3
−
−
−
JHH = 6.0 Hz, CH3 CH2 O); 4.31 (s, 2H, CH2 Ph); 6.55 (broad s, 2H, NH2); 7.22–7.44 (m,
10H, arom-H); 13C NMR (75.5 MHz, CDCl3): δ = 14.2 (s, CH3 CH2 O); 34.8 (s, Ph CH2);
−
−
−
−
−
−
− = −
−
− = −
59.6 (s, CH3 CH2 O); 106.6 (s, Ph CH2 C C S); 133.8 (s, Ph CH2 C C S); 144.2
= − = −
− −
= − −
−
(s, O C C C S); 161.1 (s, S C NH2); 166.0 (s, O C O CH2 CH3); phenyl carbons:

Journal of Sulfur Chemistry
5
δ = 125.5, 127.3, 128.4, 128.7, 129.1, 129.4, 132.2, 134.2; IR (neat): νC
= 1674 cm−1
;
=
O
−1
−
νNH2 = 3257 3414 cm
.
Ethyl 2-amino-5-benzyl-4-methylthiophene-3-carboxylate (1g).Yellow oil;Yield (%) = 57; 1H
NMR (300 MHz, CDCl3): δ = 1.15 (t, 3H, 3JHH = 6, 0 Hz, CH3 CH2 O); 2.09 (s, 3H, CH3);
−
−
3.68 (s, 2H, CH2); 4.10 (q, 2H, 3JHH = 6.0 Hz, CH3 CH2 O); 6.05 (broad s, 2H, NH2); 6.68–
−
−
7.08 (m; 5H; arom-H); 13C NMR (75.5 MHz, CDCl3): δ = 14.5 (s, CH3 CH2 O); 15.3 (s,
−
−
− = −
−
− −
−
−
− = −
CH3 C C S); 33.0 (s, Ph CH2 C S); 59.8 (s, CH3 CH2 O); 106.1 (s, CH3 C C S);
− − = −
−
− −
− −
128.6 (s, CH3 C C C S); 131.1 (s, Ph CH2 C S); 162.7 (s, S C NH2); 166.1
= − −
−
(s, O C O CH2 CH3); phenyl carbons: δ = 125.8, 126.2, 140.4, 141.0; IR (neat): νC
=
=
O
−1
1673 cm−1; νNH2 = 3271 3452 cm
.
−
3.2. General procedure for the synthesis of O-ethyl-P-aryl-N-(thiophen-2-yl)
phosphonamidothioates (2)
A mixture of ethyl 2-aminothiophene-3-carboxylate 1 (0.01 mol), LR (0.005 mol) and dry toluene
(30 ml), was heated under reflux with magnetic stirring for 72 h. The reaction mixture was then
concentrated under vacuum. The residue obtained was chromatographed on a silica gel column
using a mixture of ether and hexane (1:1) as eluent.
O-ethyl-P-(4-methoxyphenyl)-N-(4,5,6,7-tetrahydro-1-benzothiophen-2-yl)phosphonami-
dothioate (2a). Brown oil; 31P NMR (121.5 MHz, CDCl3): δ = 69.9 ppm; 1H NMR
3
−
−
(300 MHz, CDCl3): δ = 1.26 (t, 3H, JH-H = 6.0 Hz, CH3 CH2 O); 1.69–2.79 (m, 8H,
3
3
−
−
−
cyclic H); 3.72 (s, 3H, CH3 O); 4.23 (quint, 2H, JHH = JPH = 6.0 Hz, CH3 CH2 O);
6.81–7.82 (m, 5H, arom-H); 9.96 (d, 1H, JPH = 9.0 Hz, NH); 13C NMR (75.5 MHz,
2
3
−
− −
−
−
− = −
CDCl3): δ = 16.1 (d, JCP = 7.5 Hz, CH3 CH2 O P); 21.4 (s, CH2 CH2 CH2 C C S);
−
− = −
− = −
−
− = −
22.7 (s, CH2 CH2 C C S); 24.3 (s, CH2 C C S); 26.3 (s, CH2 (CH2)3 C C S);
2
−
−
− −
− = −
55.3 (s, CH3 O); 61.7 (d, JCP = 9.1 Hz, CH3 CH2 O P); 112.2 (s, CH2 C C S); 114.0
4
= −
− = −
= −
(s, CH C S); 147.0 (s, CH2 C C S); 152.6 (s, C C NH); 162.7 (d, JCP = 3.0 Hz,
= − −
C C O CH3); phenyl carbons: δ = 123.6, 124.8, 128.7, 128.9, 137.5, 137.6; IR (neat):
νP
= 738 cm−1; νNH = 3289 cm−1; EI-HRMS: calculated for C17H22NO2PS2: 367.0830 (M+),
=
S
found: 367.0826.
O-ethyl-P-(4-methoxyphenyl)-N-(5,6-dihydro-4H-cyclopenta[b]thiophen-2-yl)phosphon-
amidothioate (2b). Brown oil; 31P NMR (121.5 MHz, CDCl3): δ = 69.4 ppm; 1H NMR (300 MHz,
3
−
−
CDCl3): δ = 1.22 (t, 3H, JH-H = 6.0 Hz, CH3 CH2 O); 2.29–3.33 (m, 6H, cyclic H); 3.71
3
3
−
−
−
(s, 3H, CH3 O); 4.16 (quint, 2H, JHH = JPH = 6.0 Hz, CH3 CH2 O); 6.73–7.93 (m,
5H, arom-H); 10.24 (d, 1H; JPH = 9.0 Hz, NH); 13C NMR (75.5 MHz, CDCl3): δ = 15.6
2
(d, 3JCP = 8.3 Hz, CH3 CH2 O P); 27.8 (s, CH2 CH2 C C S); 28.6 (s, CH2 C C S);
−
− −
−
− = −
− = −
2
−
− = −
−
−
− −
29.9 (s, CH2 (CH2)2 C C S); 55.2 (s, CH3 O); 61.9 (d, JCP = 9.0 Hz, CH3 CH2 O P);
− = −
= −
− = −
= −
113.3 (s, CH2 C C S); 114.1 (s, CH C S); 141.4 (s, CH2 C C S); 150.8 (s, C C NH);
4
= − −
162.9 (d, JCP = 3.1 Hz, C C O CH3); phenyl carbons: δ = 123.5, 125.2, 128.5, 128.8,
137.8, 138.0; IR (neat): νP
= 738 cm−1; νNH = 3281 cm−1; EI-HRMS: calculated for
=
S
C16H20NO2PS2: 353.0673 (M+); found: 353.0671.
O-ethyl-P-(4-methoxyphenyl)-N-(4-phenylthiophen-2-yl) phosphonamidothioate (2c). Brown
1
oil; 31P NMR (121.5 MHz, CDCl3): δ = 75.9 ppm; H NMR (300 MHz, CDCl3): δ = 1.29
3
3
(t, 3H, 3JH-H = 6.0 Hz, CH3 CH2 O); 3.71 (s, 3H, CH3 O); 4.23 (quint, 2H, JHH = JPH
=
−
−
−
6.0 Hz, CH3 CH2 O); 6.79–7.83 (m, 11H, arom-H); 10.12 (d, 1H, JPH = 9.0 Hz, NH); 13C
2
−
−
3
−
− −
−
NMR (75.5 MHz, CDCl3): δ = 14.6 (d, JCP = 3.0 Hz, CH3 CH2 O P); 55.3 (s, CH3 O);
62.9 (d, 2JCP = 6.8 Hz, CH3 CH2 O P); 113.4 (s, Ph C C S); 113.9 (s, CH C S); 143.1
−
− −
− = −
= −
4
− = −
= −
= − −
(s, Ph C C S); 145.1 (s, C C NH); 163.1 (d, JCP = 3.0 Hz, C C O CH3); phenyl car-
bons: δ = 122.3, 123.8, 125.8, 127.3, 128.9, 129.0, 133.4, 134.5, 137.7, 137.8; IR (neat):

6
K. Khalladi and S. Touil
νP
= 736 cm−1; νNH = 3328 cm−1; EI-HRMS: calculated for C19H20NO2PS2: 389.0673 (M+),
=
S
found: 389.0678.
O-ethyl-P-(4-methoxyphenyl)-N-(4,5-dimethylthiophen-2-yl)phosphonamidothioate
(2d).
Brown oil; 31P NMR (121.5 MHz, CDCl3): δ = 69.9 ppm; 1H NMR (300 MHz, CDCl3): δ = 1.19
3
−
−
− =
− −
(t, 3H, JH-H = 6.0 Hz, CH3 CH2 O); 2.06 (s, 3H, CH3 C C); 2.15 (s, 3H, CH3 C S);
3
3
−
−
−
3.60 (s, 3H, CH3 O); 4.10 (quint, 2H, JHH = JPH = 6.0 Hz, CH3 CH2 O); 6.62–7.77 (m,
5H, arom-H); 9.83 (d, 1H, JPH = 9.0 Hz, NH); 13C NMR (75.5 MHz, CDCl3): δ = 12.6
2
3
− = −
− −
−
− −
(s, CH3 C C S); 14.4 (s, CH3 C S); 16.1 (d, JCP = 7.5 Hz, CH3 CH2 O P); 55.4
2
−
−
− −
− = −
(s, CH3 O); 61.8 (d, JCP = 5.3 Hz, CH3 CH2 O P); 113.2 (s, CH3 C C S); 114.3
4
= −
− = −
= −
(s, CH C S); 146.3 (s, CH3 C C S); 151.0 (s, C C NH); 162.8 (d, JCP = 3.0 Hz,
= − −
C C O CH3); phenyl carbons: δ = 121.6, 123.2, 129.0, 129.1, 133.7, 137.8; IR (neat):
νP
= 733 cm−1; νNH = 3271 cm−1; EI-HRMS: calculated for C15H20NO2PS2: 341.0673 (M+),
=
S
found: 341.0672.
O-ethyl-P-(4-methoxyphenyl)-N-(4-benzyl-5-phenylthiophen-2-yl)phosphonamidothioate(2e).
Brown oil; 31P NMR (121.5 MHz, CDCl3): δ = 70.5 ppm; 1H NMR (300 MHz, CDCl3): δ = 1.15
3
3
(t, 3H, 3JH-H = 6.0 Hz, CH3 CH2 O); 3.62 (s, 3H, CH3 O); 4.12 (quint, 2H, JHH = JPH
=
=
−
−
−
2
−
−
−
−
6.0 Hz, CH3 CH2 O); 4.44 (s, 2H, CH2 Ph); 6.75 8.10 (m, 15H, arom-H); 9.65 (d, 1H, JPH
12.0 Hz, NH); 13C NMR (75.5 MHz, CDCl3): δ = 16.6 (d, JCP = 3.2 Hz, CH3 CH2 O P);
3
−
− −
2
−
−
−
− −
45.2 (s, Ph CH2); 55.1 (s, CH3 O); 62.5 (d, JCP = 9.0 Hz, CH3 CH2 O P); 112.1 (s,
− = −
= −
−
− = −
= −
CH2 C C S); 114.3 (s, CH C S); 141.7 (s, PH CH2 C C S); 157.7 (s, C C NH);
163.0 (d, 4JCP = 3.1 Hz, C C O CH3); phenyl carbons: δ = 123.6, 125.2, 127.4, 128.1, 128.7,
= − −
128.9, 129.2, 129.9, 131.7, 132.1, 133.6, 134.8, 137.4, 137.6; IR (neat): νP
= 738 cm−1
;
=
S
νNH = 3338 cm−1; EI-HRMS: calculated for C26H26NO2PS2: 479.1143 (M+); found: 479.1145.
O-ethyl-P-(4-methoxyphenyl)-N-(4-methylthiophen-2-yl) phosphonamidothioate (2f). Brown
oil; 31P NMR (121.5 MHz, CDCl3): δ = 69.6 ppm; 1H NMR (300 MHz, CDCl3): δ = 1.25 (t, 3H,
3
−
−
− =
−
JH-H = 6.0 Hz, CH3 CH2 O); 2.29 (s, 3H, CH3 C C); 3.73 (s, 3H, CH3 O); 4.28 (quint,
2H, 3JHH = JPH = 6.0 Hz, CH3 CH2 O); 6.80 8.08 (m, 6H, arom-H); 10.18 (d, 1H, JPH
=
=
3
2
−
−
−
12.0 Hz, NH); 13C NMR (75.5 MHz, CDCl3): δ = 14.0 (s, CH3 C C S); 16.0 (d, JCP
3
− = −
2
−
− −
−
−
− −
7.5 Hz, CH3 CH2 O P); 55.3 (s, CH3 O); 62.8 (d, JCP = 10.3 Hz, CH3 CH2 O P); 113.3
− = −
= −
− = −
= −
(s, CH3 C C S); 114.6 (s, CH C S); 149.7 (s, CH3 C C S); 155.5 (s, C C NH); 163.1
(d, 4JCP = 3.0 Hz, C C O CH3); phenyl carbons: δ = 123.4, 125.2, 128.4, 128.7, 137.6, 137.7;
= − −
IR (neat): νP
= 736 cm−1; νNH = 3273 cm−1; EI-HRMS: calculated for C14H18NO2PS2:
=
S
327.0517 (M+), found: 327.0509.
O-ethyl-P-(4-methoxyphenyl)-N-(5-benzyl-4-methylthiophen-2-yl)phosphonamidothioate(2g).
Brown oil; 31P NMR (121.5 MHz, CDCl3): δ = 70.1 ppm; 1H NMR (300 MHz, CDCl3):
3
−
−
− =
δ = 1.30 (t, 3H, JH-H = 6.0 Hz, CH3 CH2 O); 2.28 (s, 3H, CH3 C C); 3.62 (s, 3H,
3
3
−
−
−
−
CH3 O); 3.83 (s, 2H, CH2 Ph); 4.20 (quint, 2H, JHH = JPH = 6.0 Hz, CH3 CH2 O); 6.71–
7.86 (m, 10H, arom-H); 10.00 (d, 1H, JPH = 9.0 Hz, NH); 13C NMR (75.5 MHz, CDCl3):
2
3
− = −
−
− −
−
δ = 14.3 (s, CH3 C C S); 16.1 (d, JCP = 2.3 Hz, CH3 CH2 O P); 32.9 (s, Ph CH2);
2
−
−
− −
− = −
55.1 (s, CH3 O); 60.6 (d, JCP = 9.3 Hz, CH3 CH2 O P); 113.1 (s, CH3 C C S);
4
= −
− = −
= −
114.0 (s, CH C S); 140.8 (s, CH3 C C S); 147.3 (s, C C NH); 162.6 (d, JCP
=
= − −
3.0 Hz, C C O CH3); phenyl carbons: δ = 123.3, 124.7, 126.0, 127.0, 128.1, 128.3, 129.8,
133.5, 137.6, 137.7; IR (neat): νP
= 735 cm−1; νNH = 3277 cm−1; EI-HRMS: calculated for
=
S
C21H24NO2PS2: 417.0986 (M+), found: 417.0984.
O-ethyl-P-(4-methoxyphenyl)-N-(4-methyl-5-phenylthiophen-2-yl) phosphonamidothio-ate
1
(2h). Brown oil; 31P NMR (121.5 MHz, CDCl3): δ = 70.1 ppm; H NMR (300 MHz, CDCl3):
δ = 1.46 (t, 3H, 3JH-H = 6.0 Hz, CH3 CH2 O); 2.41 (s, 3H, CH3 C C); 3.79 (s, 3H, CH3 O);
−
−
− =
−
3
3
−
−
−
4.36 (quint, 2H, JHH = JPH = 6.0 Hz, CH3 CH2 O); 6.91 8.20 (m, 10H, arom-H); 10.34
2
(d, 1H, JPH = 9.0 Hz, NH); 13C NMR (75.5 MHz, CDCl3): δ = 14.4 (s, CH3 C C S);
− = −

Journal of Sulfur Chemistry
7
3
2
−
− −
−
16.2 (d, JCP = 7.5 Hz, CH3 CH2 O P); 55.3 (s, CH3 O); 61.9 (d, JCP = 13.6 Hz,
−
− −
− = −
= −
= − −
− = −
CH3 CH2 O P); 113.9 (s, CH3 C C S); 114.2 (s, CH C S); 148.6 (s, CH3 C C S);
4
= −
153.9 (s, C C NH); 163.0 (d, JCP = 3.1 Hz, C C O CH3); phenyl carbons: δ = 125.4,
126.7, 127.7, 128.6, 128.8, 129.8, 130.5, 133.5, 137.7, 137.8; IR (neat): νP
= 737 cm−1
;
=
S
νNH = 3286 cm−1; EI-HRMS: calculated for C20H22NO2PS2: 403.0830 (M+), found: 403.0826.
Acknowledgements
We thank the Tunisian Ministry of Higher Education and Scientific Research for financial support.
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