Synthesis of new heterocyclic compounds using Lawesson reagent

Article abstract of DOI:10.1080/104265090970197

Lawesson reagent 1 reacts with Mannich bases of β-naphthol 2 and 8-hydroxyquinoline 4 to give oxthiaphosphinine-3-sulfide derivatives 3 and 5, respectively. Reaction of 1 with benzaldehyde in the presence of trialkyl phosphite yields 1,3,5,2-trithiaphosph

Full text of DOI:10.1080/104265090970197

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Phosphorus, Sulfur, and Silicon
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Synthesis of New Heterocyclic
Compounds Using Lawesson
Reagent
Ahmed A. El-Kateb a & Naglaa M. Abd El-Rahman a
a Department of Pesticide Chemistry , National
Research Centre , Dokki, Cairo, Egypt
Published online: 16 Aug 2006.
To cite this article: Ahmed A. El-Kateb & Naglaa M. Abd El-Rahman (2006) Synthesis
of New Heterocyclic Compounds Using Lawesson Reagent, Phosphorus, Sulfur, and
Silicon and the Related Elements, 181:2, 249-254, DOI: 10.1080/104265090970197
To link to this article: http://dx.doi.org/10.1080/104265090970197
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Phosphorus, Sulfur, and Silicon, 181:249–254, 2006
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/104265090970197
Synthesis of New Heterocyclic Compounds Using
Lawesson Reagent
Ahmed A. El-Kateb
Naglaa M. Abd El-Rahman
Department of Pesticide Chemistry, National Research Centre,
Dokki, Cairo, Egypt
Lawesson reagent
1 reacts with Mannich bases of β-naphthol 2 and 8-
hydroxyquinoline 4 to give oxthiaphosphinine-3-sulfide derivatives 3 and 5, respec-
tively. Reaction of 1 with benzaldehyde in the presence of trialkyl phosphite yields
1,3,5,2-trithiaphosphinane-2-sulfide derivative 8 and, in the presence of ethyl acry-
late, affords 2,4,6-triphenyl-1,3,5-trithiane 9. A mechanism is proposed to explain
the formation of adduct 3.
Keywords Mannich bases; Lawesson reagent; benzaldehyde; trialkyl phosphite; ethyl
acrylate
INTRODUCTION
In previous articles1−3 we reported on the reactions of 2,4-bis-(4-
methoxy-phenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulphide (Lawes-
son reagent) 1 with certain active centers. Extending this work, we
have now investigated the reactions of reagent 1 with some Mannich
bases and benzaldehyde.
RESULTS AND DISCUSSION
We have found that compound 1 reacts with 1-dimethylaminomethyl-
2-naphthol 2 in refluxing dry toluene to give 3-(4-methoxyphenyl)-1H-
naphtho [1,2-e]-1,3,2-oxathiaphosphinine-2-sulfide 3. Structure 3 is de-
duced from correct microanalyses, MS, IR, 1H-NMR, and 31P-NMR.
(a) Elemental analyses and the molecular weight determination of
adduct 3 correspond to C18H15O2PS2.
Received October 16, 2004; accepted February 7, 2005.
Address correspondence to Naglaa M. Abd El-Rahman, National Research Centre, De-
partment of Pesticide Chemistry, Dokki, Cairo, 12622 Egypt. E-mail: naglaa r@yahoo.com
249

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A. A. El-Kateb and N. M. Abd El-Rahman
(b) The MS of 3 showed a prominent peak at m/e 358 (M+, 50%); the
loss of the S atom from the M+ affords the positive ion radical at m/e
326 (49%); the further loss of the S atom from the latter gives rise to the
positive radical ion at m/e 294 (30%); the ejection of the CH3O-C6H4-PO
radical from the latter gives a radical at 140 (75%). Also there is a peak
at 156 (25%), which originates from the expulsion of the CH3O-C6H4-
PS2 radical from the parent ion.
(c) The IR spectrum of adduct 3 (in KBr) reveals the absence of the
OH group of the Mannich base; it gives an absorption band at 1445 (P-
1
C-aryl),4 and 1595 (C=C aromatic). (d) The H-NMR showed a singlet
at δ = 3.9(3H, OCH3), two triplets at δ = 4.7 and 4.11 with a coupling
constant J = 16.50 Hz (for the two unequivalent hydrogen atoms of
HH
the CH2 group), and a multiplet at δ = 7.25 − 8.10 (10 H, aromatic pro-
tons). (e) The 31P-NMR gave a positive chemical shift (vs. 85% H3PO4)
at δ = 90.95 ppm.5
Adduct 3 can be hydrolyzed by the action of alcoholic hydrochlo-
ric acid on refluxing to give 1ꢀ,2,2ꢀ,3-tetrahydro-4-hydroxyphenalene-
1-spiro-1ꢀ-naph-thalene-2ꢀ-one 7 through the dimerization of A to give
6 and the rearrangement of 6. Compound 7 was identified from m.p.,
mixed m.p. 239◦C, IR, and MS with an authentic sample (cf. Scheme 1).6
A mechanism accounting for the formation of structure 3 is de-
picted in Scheme 2. The Mannich base 2 loses a molecule of dimethy-
lamine to give the o-quinonemethide A; a nucleophilic attack on the
methine group of A by the sulfur anion of the monomeric species B
existing probably in equilibrium with reagent7−9 1 can produce the
dipolar form C. The latter undergoes ring closure to give the end
product 3.
In a similar manner, reagent 1 reacts with 7-dimethylaminomethyl-
8-hydroxyquinoline 4 in refluxing toluene to yield 2-(4-methoxyphenyl)-
4H-[1,3,2]-oxathiaphosphinino[5,6-H]quinoline-2-sulfide 5, which is
verified by spectral data and correct combustion values, which corre-
spond to C17H14NO2PS2 (cf. Experimental).
Next, when reagent 1 is allowed to react with benzaldehyde in
refluxing toluene, a polymerized product is formed, which could not
be isolated, but when the same reaction is repeated in the presence
of trimethyl or triethyl phosphite, 2-(4-methoxyphenyl)-4,6-diphenyl-
1,3,5,2-trithiaphosphinane-2-sulfide 8 is produced. Structure 8 is based
on the correct microanalyses, which correspond to C21H19OPS4 and
on 1H-NMR, MS, and 31P-NMR. The 1H-NMR gave a singlet at
δ = 3.95 (3H, OCH3), a doublet at δ = 6.82 with coupling constant
J
= 12.50 Hz(2H, 2 C6 H5 CH), and a multiplet at δ = 7.40 − 8.20
HP
(14 aromatic protons). The 31P-NMR gave a chemical shift at around
δ = 89.05.10 The same adduct 8 is obtained when we used triethylamine

251

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A. A. El-Kateb and N. M. Abd El-Rahman
SCHEME 2
instead of trialkyl phosphite. This may explain that trialkyl phosphite
acts as a base in this reaction.
When we use ethyl acrylate in the reaction of 1 with benzaldehyde
in refluxing toluene, 2, 4, 6-triphenyl-1,3,5-trithiane 9 is isolated. The
formation of the adduct 9 arises from the thiation of benzaldehyde by
reagent 1 to give thiobenzaldehyde which polymerized under the ex-
perimental condition to give the trimer 9. Structure 9 is based on the
correct analytical and spectroscopic evidence (cf. Experimental).
This finding gives us the idea that using L.R. represents a novel
route for the synthesis of heterocyclic systems containing a phosphorus
and/or sulfur moiety; these heterocyclic systems are interesting in the
field of pesticidal chemistry.
EXPERIMENTAL
All melting points are uncorrected. The IR spectra were measured in
KBr on a Perkin-Elmer Infracord spectrometer Model 157G (Grating).
The 1H-NMR spectra were done on a JEOL JNM-EX 270 FTNMR sys-
tem. The 31P-NMR spectra were run on a Varian FT-80 spectrome-
ter (vs. 85% H3PO4). The MS spectra were performed at 70 eV on a

Synthesis of New Heterocyclic Compounds
253
Finnigan MAT SSQ 7000 spectrometer. The microanalyses were car-
ried out at the Microanalytical Centre, Cairo University, Cairo, Egypt.
Reaction of Mannich Base 2 or 4 With Lawesson Reagent 1
A mixture of the Mannich base 2 or 4 (0.001 mole) and reagent 1
(0.001 mole) in 40 mL of dry toluene was refluxed for 12 h. After cooling
to r.t., the reaction mixture was evaporated on silica gel under reduced
pressure and applied to a silica-gel column using the suitable solvent
stated in the following section.
3-(4-Methoxyphenyl)-1H-naphtho-[1,2-e][1,3,2]-
oxathiaphosphinine-2-sulfide (3)
Eluent, methylene chloride/petroleum ether 40/60 (2:3), yield 62%,
pale yellow crystals m.p. 220◦C; C18H15O2PS2(358), Calcd: C, 60.32; H,
4.22; P, 8.64; S, 17.98. Found: C, 60.30; H, 4.30; P, 8.69; S = 18.00.
2-(4-Methoxyphenyl)-4H-[1,3,2]oxathiaphosphinino[5,6-h]-
quinoline-2-sulfide (5)
Eluent, acetone/petroleum ether (1:3), yield 51%, straw yellow crys-
1
tals m.p. 198◦C. IR, 1445 (P-C-aryl), 1570–1580 (C=C aromatic). H-
NMR, δ = 3.8(3H, OCH3), δ = 7.15 − 7.85 (9 aromatic protons, m), δ =
4.8 (2H, CH2, d, J = 13.00 Hz). C17H14NO2PS2 (359.4), Calcd: C,
HP
56.81; H, 3.93; N, 3.90; P, 8.62; S, 17.84. Found: C, 56.79; H, 3.90; N,
3.92; P, 8.68; S, 17.92. MS, 359 (M+), 327 (M+-S), 295 (327-S), 141 (295-
CH3O-C6H4PO).
Action of Alcoholic Hydrochloric Acid on 3
Adduct 3 (0.001 mole) in 7 mL of HCl (20%) and 3 mL of ethanol were
refluxed on a water bath for 2 h; the mixture was concentrated on a
water bath and neutralized with 5% NaOH. The precipitate formed
was collected and extracted with ethyl acetate to give 7; m.p. and mixed
m.p. 239◦C, MS, 312 (100%); IR and NMR are identical with that of the
authentic sample.6
Reaction of Reagent 1 With Benzaldehyde in the Presence
of Trialkyl Phosphite
A mixture of 1 (0.005 mole), benzaldehyde (0.005 mole), and trimethyl
or triethyl phosphite (0.005 mole) was refluxed in dry toluene (40 mL)
for 15 h, the volatile materials were removed under reduced pressure,
then the residue was placed on a column of silica gel and eluted with

254
A. A. El-Kateb and N. M. Abd El-Rahman
a mixture of chloroform/petroleum ether (3:1) to give 8 in a 55% yield;
m.p. 188◦C, MS, 446 (M+ 30%), 324 (M+-C6H5CHS, 202 (324-C6H5S),
138 (202-2S).
Reaction of 1 with Benzaldehyde in the Presence
of Ethyl Acrylate
In a similar manner, 1 reacted with benzaldehyde in the presence of
ethyl acrylate (0.005 mole) eluted with acetone/petroleum ether (1:2),
and gave 9 as pale yellow crystals, m.p. 150◦C in a 45% yield. The 1H-
NMR of 9 showed a singlet at δ = 5.85 (3H, 3 C6H5CH), δ = 7.30 − 7.50
(15 aromatic protons multiplet). C21H18S3 (363.5), Calcd: C, 68.81; H,
4.95; S, 26.24. Found: C, 68.83; H, 4.93; S, 26.22. MS, 366 (M+ 100%),
244 (M+-C6H5CHS 80%), 122 (244-C6H5CHS 70%) and 90 (122-S, 20%).
REFERENCES AND NOTES
[1] A. A. El-Kateb, I. T. Hennawy, R. Shabana, and H. A. Abdel-Maleck, Phosphorus,
Sulfur, and Silicon, 63, 13 (1991).
[2] A. A. El-Kateb, R. Shabana, and F. H. Osman, Z. Naturforsch, 39, 1614 (1984).
[3] A. A. El-Kateb, I. T. Hennawy, R. Shabana, and F. H. Osman, Phosphorus and Sulfur,
20, 329 (1984).
[4] M. Hesse, H. Meier, and B. Zech, Spectroskopische Methoden in der Organischen
Chemie (G. Thiem Verlag, Stuttgart), 1979.
[5] A. A. El-Barbary and S. O. Lawesson, Tetrahedron, 37, 2641 (1981).
[6] G. Catterall, J. Chem. Soc. Chem. Comm., 41 (1974).
[7] M. Yoshifuji, K. Toyta, K. Ando and N. Inamoto, Chem. Lett., 317 (1984).
[8] R. Appel, F. Knoch, and H. Kunze, Angew. Chem., 95, 1008 (1983).
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(1983).
[10] S. Scheiby, R. Shabana, S. O. Lawesson, and C. Roemming, Tetrahedron, 38, 993
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