One-pot synthesis and fungicidal activity of pyrimidinylidenamido- and thiazolinylidenamidomonothiophosphoric esters

Article abstract of DOI:10.1080/10426500307803

A novel one-pot synthesis of four new classes of amidothiophosphoric esters and trisamidothiophosphoric esters is developed. (1-Alkyl-2-pyrimidinylidenamido)bis(diethylamido)thiophosphates, (1-alkyl-2-pyrimidinylidenamido)bis(O-214-methylphenyl)thiophosphates, (3-alkyl-2-thiazolinylidenamido)bis (diethylamido)thiophosphate and (3-alkyl-2-thiazolinylidenamido)bis(O-214-methylphenyl)thiophosphates are obtained from the nucleophilic substitution and oxidation of N-alkyl-2-cycloiminylidenaminodichlorophosphines generated in situ from the reaction of the corresponding N-alkyl-2-amino-cycloiminium halide with phosphorus trichloride and triethylamine. The synthesized thiophosphoric esters have been investigated for fungicidal properties.

Full text of DOI:10.1080/10426500307803

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Phosphorus, Sulfur, and Silicon and the Related
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One-Pot Synthesis and Fungicidal
Activity of Pyrimidinylidenamido- and
Thiazolinylidenamidomonothiophosphoric Esters
Neelima Gupta a , Vijaya Kabra a , Varsha Saxena a , Sama Jain a & Kalpana Bhatnager b
a University of Rajasthan , Jaipur, India
b A.R.S. , Jaipur, India
Published online: 27 Oct 2010.
To cite this article: Neelima Gupta , Vijaya Kabra , Varsha Saxena , Sama Jain & Kalpana Bhatnager (2003) One-Pot Synthesis
and Fungicidal Activity of Pyrimidinylidenamido- and Thiazolinylidenamidomonothiophosphoric Esters, Phosphorus, Sulfur, and
Silicon and the Related Elements, 178:4, 851-861, DOI: 10.1080/10426500307803
To link to this article: http://dx.doi.org/10.1080/10426500307803
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Phosphorus, Sulfur and Silicon, 2003, Vol. 178:851–861
C
Copyright 2003 Taylor & Francis
1042-6507/03 $12.00 + .00
DOI: 10.1080/10426500390198011
ONE-POT SYNTHESIS AND FUNGICIDAL ACTIVITY
OF PYRIMIDINYLIDENAMIDO- AND
THIAZOLINYLIDENAMIDOMONOTHIOPHOSPHORIC
ESTERS
Neelima Gupta,a Vijaya Kabra,a Varsha Saxena,a Sama Jain,a
and Kalpana Bhatnagerb
University of Rajasthan, Jaipur, Indiaa and
A.R.S., Jaipur, Indiab
(Received August 12, 2002; accepted September 29, 2002)
A novel one-pot synthesis of four new classes of amidothiophosphoric
esters and trisamidothiophosphoric esters is developed. (1-Alkyl-2-
pyrimidinylidenamido)bis(diethylamido)thiophosphates, (1-alkyl-2-
pyrimidinylidenamido)bis
(3-alkyl-2-thiazolinylidenamido)bis
and (3-alkyl-2-thiazolinylidenamido)bis(O-2/4-methylphenyl)thio-
(O-2/4-methylphenyl)thiophosphates,
(diethylamido)thiophosphate
phosphates are obtained from the nucleophilic substitution and
oxidation of N-alkyl-2-cycloiminylidenaminodichlorophosphines gen-
erated in situ from the reaction of the corresponding N-alkyl-2-amino-
cycloiminium halide with phosphorus trichloride and triethylamine.
The synthesized thiophosphoric esters have been investigated for
fungicidal properties.
Keywords: Alkylidenamidothiophosphates; amidothiophosphoric
esters; trisamidothiophosphoric esters; fungicidal activity
Functionalized halophosphines have been used widely as precursors
for the synthesis of a variety of organophosphorus compounds hav-
ing phosphorus in different oxidation states;1,2 including phosphoric
esters, thiophosphoric esters, and amidophosphoric esters; a number
of representatives of which are known for their insecticidal and fungici-
dal properties.3–6 Synthesis of amidophosphoric, amidothiophosphoric,
We acknowledge CSIR, New Delhi for financial support and ARS, Jaipur for providing
facilities for determination of fungicidal activity. Thanks also are due to RSIC, Lucknow
for providing C, H, N analysis data and NMR spectra.
Address correspondence to Vijaya Kabra, University of Rajasthan, Department of
Chemistry, Jaipur 302 004, India. E-mail: sgkabra@sancharnet.in
851

852
N. Gupta et al.
and trisamidophosphoric ester derivatives has been reported from
the reaction of 2-aminopyridine with dimethylphosphoric chloride, di-
ethylthiophosphoric chloride, and bis(phenylamido)phosphoric chlo-
ride respectively.7 Alternatively, trisamidophosphoric esters have been
prepared from the reaction of amidophosphoric dichloride with
amines8,9 or oxidation of tris-amidophosphorus.8 Dehydrosulfuration
of (OR)2P(S)NHCSNHPh yielded (OR)2P(S)N:C:NPh; the latter on
further reaction with 2-bromoethylamine hydrobromide gave imida-
zolidinylidenamidothiophosphoric esters.10 Alkylidenamido-bis(amido)
phosphoric esters have been obtained from the reaction of
bis(dimethylamino)chlorophosphine with ketoximes11 or the substi-
tution of chlorines from alkylidenamidophosphoric dichloride with
amines.12,13
Recently, a novel class of halophosphines, namely N-alkyl-2-
cycloiminylidenaminodichlorophosphines has been reported as an
intermediate during the synthesis of anellated diazaphospholes.14–16
In view of the electrophilic as well as nucleophilic nature of the
phosphorus of the halophosphine moiety,17 the chlorine atoms of these
aminodichlorophosphines may undergo substitution accompanied by
the oxidation of phosphorus18 to form a novel class of alkylidenamidoth-
iophosphates incorporating a variety of nitrogen heterocycles. A novel
one-pot synthesis of four new classes of amidothiophosphoric esters
and trisamidothiophosphoric esters namely, (1-alkyl-2-pyrimidinyl-
idenamido)bis(diethylamido)thiophosphates, (1-alkyl-2-pyrimidinyli-
denamido)bis(O-2/4-methylphenyl)thiophosphates, (3-alkyl-2-thiazoli-
nylidenamido)bis(diethylamido)thiophosphate, and (3-alkyl-2-thiazol-
inylidenamido)bis(O-2/4-methylphenyl)thiophosphates from N-alkyl-
2-cycloiminylidenaminodichlorophosphines generated in situ from
the reaction of corresponding N-cycloiminium salt with phosphorus
trichloride is reported here. Fungicidal properties of these thiophos-
phates have been investigated against Fusarium oxysporium and
Alternaria cymopsidies.
RESULTS AND DISCUSSION
(1-Alkyl-2-pyrimidinylidenamino)dichlorophosphine 2a–c is generated
in situ ( 31P 191) from the reaction of 1-alkyl-2-aminopyrimidinium
halide 1a–c with phosphorus trichloride (1 equivalent) and triethy-
lamine (2 equivalents) in methylene chloride at 0–5 C. Further ad-
dition of a four-fold amount of diethylamine and equimolar amount
of sulfur results in the formation of (1-alkyl-2-pyrimidinylidenamido)
bis(diethylamido)thiophosphates 3a–c (Scheme 1).

Synthesis and Fungicidal Activity of Amidothiophosphoric
853
SCHEME 1
Analogously, from the reaction of 2-amino-3-methylthiazolinium
iodide 5a with phosphorus trichloride (1 equivalent) and tri-
ethylamine (2 equivalent) followed by reaction with diethylamine
(4 equivalents) and simultaneous oxidation with sulfur (3-methyl-2-
thiazolinylidenamido)bis(diethylamido)thiophosphate 7a is obtained
(Scheme 2).
SCHEME 2
The reaction of 1a or 1b with o-cresol (2 equivalents) and 1a or
5c with p-cresol (2 equivalents) and triethylamine (2 equivalents)

854

855

856
N. Gupta et al.
in place of diethylamine under similar conditions affords (1-benzyl-
2-pyrimidinylidenamido)bis(O-2-methylphenyl) thiophosphate 4a,
{1-(4-methylbenzyl)-2-pyrimidinylidenamido}bis(O-2-methylphenyl)
thiophosphate 4b, (1-benzyl-2-pyrimidinylidenamido)bis(O-4-methyl-
phenyl) thiophosphate 4c, and {3-(4-methylbenzyl)-2-thiazolinylidena-
mido}bis(O-4-methylphenyl)thiophosphate 8a respectively (Schemes 1
and 2).
The products thus obtained are stable cream to yellow crystalline
solids characterized by elemental analysis and NMR spectroscopy
(Table I). The 31P NMR signal of 3 and 5 appears at
66, which is in
the range of trisamidothiophosphates.19 The 31P NMR signals of 4a–c
and 8a in the range 58–61 is again characteristic for tetracoordinated
pentavalent phosphorus compounds.19,20 However, the reaction of 2c
generated from 1c with o-cresol and sulfur is not complete and a mono-
substituted product 4d0 also is obtained in addition to 4d, as revealed
by the appearance of two signals at 61.5 and 58.6 in the 31P NMR spec-
1
trum of the isolated product. In H NMR spectrum a singlet at 2.37
is assigned to the six protons of the two methyl groups of cresol corre-
sponding to 4d and the singlet at 2.42 to three protons of one 2-methyl
substituent of 4d0. Similarly, the products isolated from the reactions of
6a with p-cresol and 6a,b with o-cresol also are found to be mixtures of
mono-(8b0–d0) and disubstituted (8b–d) compounds (Scheme 2), separa-
tion of which could not be accomplished by recrystallization. In the case
of the 4-methyl substituent, disubstituted product (8b) is obtained in
larger amount (85%); while in the case of the 2-methyl substituent, the
major component (71–63%) of the product mixture is monosubstituted
(8c0 and 8d0), indicating that the steric crowding plays an important
role on the completion of reaction.
FUNGICIDAL PROPERTIES
The products 3, 4, 7, and 8 have been screened for fungicidal properties
against two fungi, namely Fusarium oxysporium and Alternaria cy-
mopsidies at two concentrations of 100 and 500 ppm, and the results in
terms of the radial growth and statistical analysis are given in Table II.
All the compounds tested for both test fungi have been found to show
significant fungicidal properties in terms of the reduced radial growth
wth reference to the control average growths of 84–85% at two con-
centrations of 5% and 1%. More significant results have been obtained
at 5% concentration. Among the trisamodothiophosphate derivatives,
those (3a,b) with bulkier benzyl or p-methylbenzyl substituent at en-
docyclic nitrogen show stronger fungitoxic activity against both fungi.

Synthesis and Fungicidal Activity of Amidothiophosphoric
857
TABLE II Fungicidal Activity of the Compounds 3, 4, 7, 8
Average Radial Growth in mm (range)
Fusarium oxysporium
100 ppm 500 ppm
Alternaria cymopsidies
100 ppm 500 ppm
Cpd.
3a
3b
3c
4a
4c
7a
8a
60.72 (47.5–82.5) 25.83 (25.0–27.0) 60.83 (47.5–82.5) 16.67 (15.0–19.0)
59.17 (57.5–60.0) 24.50 (23.5–25.0) 78.67 (70.0–87.5) 17.50 (15.0–20.0)
49.17 (45.0–52.5) 42.33 (35.0–55.0) 72.50 (60.0–82.5) 69.17 (60.0–77.5)
64.17 (60.0–67.5) 45.00 (37.5–50.0) 75.00 (75.0–75.0) 51.67 (50.0–55.0)
25.00 (25.0–25.0) 22.67 (21.0–25.0) 86.50 (82.5–90.0) 66.67 (62.5–72.5)
49.17 (40.0–57.5) 39.17 (35.0–45.0) 71.67 (70.0–72.5) 70.83 (67.5–75.0)
28.00 (25.0–30.0) 16.40 (15.0–17.5) 60.00 (47.5–70.0) 34.67 (29.0–45.0)
63.33 (60.0–65.0) 26.67 (22.5–30.0) 44.17 (35.0–50.0) 12.50 (10.0–15.0)
80.00 (75.0–85.0) 80.00 (75.0–85.0) 84.17 (77.5–90.0) 84.17 (77.5–90.0)
8b
Acetone
(Solvent)
Control
84.17 (80.0–87.5) 84.17 (80.0–87.5) 85.00 (80.0–90.0) 85.00 (80.0–90.0)
GM 56.29, 40.67, 69.90, 43.57.
F cal (9.20) 21.35, 66.28, 6.42, 83.96.
SEM 2.29, 1.59, 2.90, 1.70.
CD 5% 6.76, 4.70, 8.56, 5.01.
CV% 12.87, 12.39, 13.13, 12.33.
However, in the case of amidothiophosphates 4 and 8, the fungitoxic ac-
tivity is more significant against Fusarium oxysporum than Alternaria
cymopsidies.
EXPERIMENTAL
All reactions were carried out under nitrogen atmosphere using Schlenk
techniques. Solvents were distilled and dried using standard proce-
dures and commercial reagents were freshly distilled under nitrogen
atmosphere before use. Melting points were determined by capillary
method and are uncorrected. NMR data were recorded on FT NMR spec-
trometer Jeol FX-90Q at 89.5 MHz (1H NMR) and 36.23 MHz (31P NMR)
or Bruker WM-400 at 399.65 MHz (1H NMR), 161.7 MHz (31P NMR) or
Bruker DRX-300 at 300.13 MHz (1H NMR) and 121.5 MHz (31P NMR)
with reference to TMS (internal) or 85% H3PO4 (external). Elemental
analyses were carried out on Heraeus Carlo Erba 1108 analyzer.
N-Alkyl-2-aminopyrimidinium Halides (1a–c) and N-Alkyl-
2-amino/thiazolinium Halides 5a–c. General Procedure
To a solution of 2-aminopyrimidine (2.853 g, 30 mmol) or 2-amino-
thiazoline (3.064 g, 30 mmol) in tetrahydrofuran (60 mL) was added

858
N. Gupta et al.
an equimolar amount of benzyl bromide (3.6 mL), p-methylbenzyl
chloride (4.0 mL)/p-methylbenzyl bromide (5.552 g) or methyl io-
dide (1.9 mL) and the resulting mixture was stirred at room tem-
perature for 5–10 days. White or cream colored solid thus separated
was filtered, washed with diethyl ether, and used without further
purification.
(1-Alkyl-2-pyrimidinylidenamido)bis(diethylamido)-
thiophosphate (3a–c). General Procedure
To a suspension of 1-alkyl-2-aminopyrimidinium bromide (10 mmol) in
methylene chloride (30 mL) was added phosphorus trichloride (1.0 mL,
10 mmol) at 0–5 C. A solution of triethylamine (2.8 mL, 20 mmol) in
methylene chloride (10 mL) was added dropwise with stirring. The re-
action mixture was brought to room temperature and the stirring was
continued for 4–5 h. To this was added sulfur powder (320 mg, 10 mmol)
followed by dropwise addition of a solution of diethylamine (4.2 mL,
40 mmol) in methylene chloride (10 mL) while maintaining the tem-
perature at 0–5 C and the resulting mixture was stirred overnight
at room temperature. Solvent was removed under reduced pressure
and the residue extracted with diethyl ether (3 50 mL). On leaving
the combined and concentrated extract in refrigerator, 3a–c separated
as creamish white solid, which was filtered washed with hexane and
dried.
3a Yield 55%; %Calc C 58.28 H 7.22 N 17.88
%Found 58.08
3b Yield 46%; %Calc C 59.18 H 7.89 N 17.26
%Found 59.03 7.92 17.45
3c Yield 50%; %Calc C 49.49 H 8.30 N 22.20
%Found 49.37 8.33 22.17
7.18
17.95
(1-Alkyl-2-pyrimidinylidenamido)bis(O-2/4-
methylphenyl)thiophosphates (4a–d). General Procedure
Phosphorus trichloride (1.8 mL, 20 mmol) was added to a well-stirred
suspension of 1-alkyl-2-aminopyrimidinium halide (20 mmol) in methy-
lene chloride (50 mL) at 0–5 C. A solution of triethylamine (5.6 mL,
40 mmol) in methylene chloride (10 mL) was added dropwise slowly
with constant stirring. The reaction mixture was brought to room
temperature and the stirring was continued for 5 h. To this was
added sulfur powder (640 mg, 20 mmol) and triethylamine (5.6 mL,

Synthesis and Fungicidal Activity of Amidothiophosphoric
859
40 mmol) followed by dropwise addition of a solution of o- or p-cresol
(4.2 mL, 40 mmol) in methylene chloride (10 mL) over 15–20 min
while maintaining the temperature at 0–5 C. The resulting reaction
mixture stirred overnight at room temperature. Solvent was removed
under reduced pressure and the residue extracted with diethyl ether
(2
50 mL). On leaving the combined and concentrated extract in
refrigerator, 4a–c deposited as light yellow crystalline solid, which
was filtered washed with hexane and dried. However, the product
obtained from the reaction of 1c with o-cresol was found to be a
mixture of (1-methyl-2-pyrimidinylidenamido)bis(O-2-methylphenyl)-
thiophosphate (4d, 25%) and (1-methyl-2-pyrimidinylidenamido)-(O-2-
methylphenyl)thiophosphoric chloride (4d0, 75%).
4a Yield 45%; %Calc C 65.06 H 5.24 N 9.10
%Found 65.27
4b Yield 44%; %Calc C 65.66 H 5.51 N 8.83
%Found 65.79 5.47 8.77
4c Yield 40%; %Calc C 65.06 H 5.24 N 9.10
5.21
9.06
%Found 65.19
5.28
9.17
Bis(diethylamido)(3-methyl-2-
thiazolinylidenamido)thiophosphate (7a)
To a suspension of 2-amino-3-methylthiazolinium iodide (3.904 g,
16 mmol) in methylene chloride (30 mL) was added phosphorus trichlo-
ride (1.4 mL, 16 mmol) at 0–5 C. A solution of triethylamine (4.4 mL,
32 mmol) in methylene chloride (10 mL) was added dropwise with stir-
ring. The reaction mixture was brought to room temperature and the
stirring was continued for 4 h. To this was added sulfur powder (512 mg,
16 mmol) followed by dropwise addition of a solution of diethylamine
(6.6 mL, 64 mmol) in methylene chloride (10 mL) while maintaining the
temperature at 0–5 C and the resulting mixture was stirred overnight
at room temperature. Solvent was removed under reduced pressure
and the residue extracted with diethyl ether (3 50 mL). On leaving
the combined and concentrated extract in refrigerator, 7a separated
as creamish white solid, which was filtered washed with hexane and
dried.
7a Yield 56%; %Calc C 44.69 H 8.37 N 17.36
%Found 44.75
8.28
17.11

860
N. Gupta et al.
(3-Alkyl-2-thiazolinylidenamido)bis(O-2/
4-methylphenyl)thiophosphate (8a–d) and
(3-Alkyl-2-thiazolinylidenamido)(O-2/4-methylphenyl)-
thiophosphoric Chloride(8b’–d’). General Procedure
Phosphorus trichloride (0.9 mL, 10 mmol) was added to a well-stirred
suspension of 3-alkyl-2-aminothiazolinium halide (10 mmol) in methy-
lene chloride (40 mL) at 0–5 C. A solution of triethylamine (2.8 mL,
20 mmol) in methylene chloride (10 mL) was added dropwise with con-
stant stirring. The reaction mixture was brought to room temperature
and the stirring was continued for 6 h. To this was added sulfur pow-
der (320 mg, 10 mmol) and triethylamine (2.8 mL, 20 mmol) followed
by dropwise addition of a solution of o- or p-cresol (2.1 mL, 20 mmol)
in methylene chloride (10 mL) over 15–20 min while maintaining the
temperature again at 0–5 C. The resulting reaction mixture was stirred
overnight at room temperature. Solvent was removed under reduced
pressure and the residue extracted with diethyl ether (2 50 mL). On
leaving the combined and concentrated extract in refrigerator, white to
pale crystalline solid deposited, which was filtered washed with hexane
and dried. Except 8a, the product was found to be a mixture of 8 and 80.
8a Yield 40%; %Calc C 62.21 H 5.60 N 5.80
%Found 62.34
5.54
5.71
Fungicidal Activity
A standard method to evaluate the fungitoxic properties of the com-
pounds was adopted here. Using the poison food technique, the two
pathogens, Fusarium oxysporium and Alternaria cymopsidies, were iso-
lated from the Cumin (Cuminum cyminum) and cluster bean (Cymopsis
tetragonal) crops, respectively on 2% sterile potato-dextrose agar (PDA)
medium. Test compounds were added to this in two concentrations (100
ppm and 500 ppm). This poisoned medium was poured into petriplates
(90 mm diameter) and was inoculated by inoculum disk of 3 mm diam-
eter cut from the margin of a 6-day old culture of the test pathogen and
incubated at 26 C. Each experiment was replicated three times and a
suitable control without the test compound was also maintained. The
radial growth of the mycelium was measured in mm after 6 days.
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Synthesis and Fungicidal Activity of Amidothiophosphoric
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