Fused phosphono substituted O-, and N-heterocycles via condensative cyclisation reactions of α-phosphonyl carbanions with 4-thiazolidinones

Article abstract of DOI:10.1080/10426500490468119

Phosphono substituted-thiazolones 5a,b together with fused phosphono-pyran-5-ones 9a,b and the diolefins 8a-d were regioselectively prepared in reasonable yields from the reactions of 5-arylidene-4- thiazolidinones 1a,b with phosphonoacetates 2a,b. Conversely, Michael addition products 11a,b (～30%) along with the phosphono substituted-thiazole derivatives 12a,b (～33%) were obtained from treating 1a,b with cyanomethylenephosphonates (2c). The reactions of 1a,b with vinylphosphonate 2d proceeded with phase-transfer catalysis, yielding the corresponding 2-thioalkyl-derivatives 14a,b and phosphonates 13a,b.

Full text of DOI:10.1080/10426500490468119

Phosphorus, Sulfur, and Silicon, 179:1307–1322, 2004
ꢀC
Copyright Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500490468119
FUSED PHOSPHONO SUBSTITUTED O-, AND
N-HETEROCYCLES VIA CONDENSATIVE
CYCLISATION REACTIONS OF α-PHOSPHONYL
CARBANIONS WITH 4-THIAZOLIDINONES
Wafaa M. Abdou and Maha D. Khidre
National Research Centre, Dokki, Cairo, Egypt
(Received July 3, 2003; accepted November 7, 2003)
Phosphono substituted-thiazolones 5a,b together with fused
phosphono-pyran-5-ones 9a,b and the diolefins 8a–d were re-
gioselectively prepared in reasonable yields from the reactions of
5-arylidene-4-thiazolidinones 1a,b with phosphonoacetates 2a,b.
Conversely, Michael addition products 11a,b (∼30%) along with
the phosphono substituted-thiazole derivatives 12a,b (∼33%) were
obtained from treating 1a,b with cyanomethylenephosphonates (2c).
The reactions of 1a,b with vinylphosphonate 2d proceeded with phase-
transfer catalysis, yielding the corresponding 2-thioalkyl-derivatives
14a,b and phosphonates 13a,b.
Keywords: 4-Thiazolidinones; condensative cyclization reaction; phos-
phonyl carbanions
Thiazolidinones have been recently exploited as herbicides, acaricides,
and insecticides, in which many compounds have commercially been
produced.1 The biological activity, to a large degree, is attributed to the
nature of the substituent in the thiazolidine ring. In fact, it has been
shown that the phosphonyl group could regulate important biological
functions of the substrate.2 Thus, it is conceivable that molecular modi-
fication of thiazole rings by introducing organophosphorus functionality
is likely to reveal potential pesticide activity. Although some synthetic
approaches to phosphonyl thiazolidinones have been reported,3 there
is still much active research in this area.
In a series of articles from this laboratory, we reported4 on the
synthesis and reactions of new phosphono substituted-heterocycles
starting from the inexpensive and easily accessible α-phosphonyl
carbanions. This article describes the results of our studies on the
Address correspondence to Wafaa M. Abdou, Department of Pesticide Chemistry,
National Research Centre, Dokki, Cairo, Egypt. E-mail: wabdou@intouch.com
1307

1308
W. M. Abdou and M. D. Khidre
preparation and reactions of novel phosphono substituted-heterocycles
derived from the reactions of thioxothiazolidinones 1a,b with different
types of α-phosphonyl carbanion 2a–d. Similarities and differences in
the reactivity of phosphonates 2 and phosphorane counterparts 3 to-
ward 4-thiazolidinones 1 are also discussed.
RESULTS AND DISCUSSION
When 5-arylmethylene-2-thioxo-4-thiazolidinone 1a (also known as 5-
arylidine-rhodanines1) was treated with an excess of diethyl phos-
phonoacetates 2a,b in alcoholic sodium methoxide solution at room
temperature, the reaction was not complete even after 3 days. The
product mixture was then subjected to column chromatography to
give in each case, a colored solid (∼52%) together with an un-
changed substrate 1a (∼20%). This product, for which the structure
of diethyl [5-arylmethylene-3,4-dioxo-3, 4H-2,7-dihydrothiazolo[8,7-
c]thiazol-2-yl] phosphonate 5a was proposed, was the only one produced
regardless of the ratio of the reactants employed. Similar treatment of
1b with the phosphonates 2a,b afforded the phosphonate analog 5b
(58%) and an unchanged 1b (18%). However, in all cases, 2a,b were uti-
lized in three-fold molar excess, compared to the corresponding 1a,b,
in order to obtain reasonable yields. Similar fused-thiazole derivatives
to 5 are, however, known in the literature.1b,5
Mass spectra and elemental analyses of 5a,b indicated that the reac-
tion results in a 1:1 condensative cyclisation accompanied by extrusion
of the appropriate alcohol molecule (Scheme 1). Structure 5 (δp = ∼ 19.3
ppm) was, however, established on the basis of IR and NMR spectra.
Thus, each of the products exhibited a carbonyl group, similar to that of
the starting substrate 1 (ν ∼ 1698 cm−1). The 1H NMR spectra showed
a common one-proton singlet near δ 7.8 ppm assignable to the vinylic
proton resonance. The starting thiazolidinones 1 exhibited such a sig-
nal at δH = ∼ 7.83 ppm. On the other hand, the 13C NMR6 spectra of
5 (in CDCl3) showed the absence of a thiocarbonyl carbon atom (C S)
at ∼195 ppm. Instead, the two carbonyl-carbon atoms in 5 gave two

Phosphono Substituted O-, and N-Heterocycles
1309
SCHEME 1
signals around ∼160 ppm. The phosphonate-carbon atom (C P) sig-
nal was observed at ∼48 ppm (d, 1 J = ∼187 Hz) in the 13C NMR
c-p
of 5. These values coincide with the chemical shift expected for a ring
sp3-carbon atom bearing a phosphonyl moiety as indicated by the large
coupling constant.
The foregoing results confirm the assigned structure 5 and rule out
the alternative structure 9 (Scheme 2). Consequently, the studied reac-
tion is site selective leading, under the prevailing experimental condi-
tions, to the exclusive formation of 5a,b. Similar thiophilic addition by
carbanions at the =S are known.7,8 Furthermore, considering the inter-
esting parallel between the chemistry of phosphonyl and phosphonium
ylides, similar observation were previously reported for the reaction of
alkylidenephosphoranes with thiocarbonyl compounds,7,8 as well as for
the reactions of alkyl phosphites with thiobenzophenones and others.9
When the above reaction (1a,b + 2a,b) was carried out at reflux
temperatures, we observed that the diolefins 8a–d and the phospho-
nates 9a,b were isolated in almost equal yields (∼30%) together with a
low yield of 5 (∼12%). The oxidation of 9a,b with N-bromosuccinimide
(NBS), in carbon tetrachloride containing a catalytic amount of diben-
zoyl peroxide, led to the formation of the dehydrogenated products
10a,b (∼62%) (Scheme 2). Elemental analyses, molecular weight mea-
surement (MS), IR and NMR spectroscopy (see Experimental section)
all have confirmed the structures of the new products.
The reaction mechanisms illustrated in Schemes 1 and 2 are pos-
tulated as follows: thiophilic addition of the phosphonyl carbanion 2
to thiazolidinone 1 yields the intermediate 4. At low temperature, the
latter undergoes intramolecular cyclisation giving the fused thiazolone
5 via elimination of the appropriate alcohol molecule and protonation
from the solvent (Scheme 1). However, at relatively high temperature,

1310
W. M. Abdou and M. D. Khidre
SCHEME 2
thiocarbonyl olefination of 1a,b has occurred by one mole of Wittig-
Horner reagents 2a,b to give the olefin 6. Michael addition of a second
carbanion species 2a or 2b followed by rearrangement affords the prod-
uct 8 via 8A with concomitant Hofmann type elimination of phosphorus
group [(RO)2PO] as dialkyl phosphonate. A similar result was reported
for the reaction of 2-thiono-1,2,4-oxodiazole with 2a,b.10 Furthermore,
the high temperature allows the formation of the Michael addition

Phosphono Substituted O-, and N-Heterocycles
1311
SCHEME 3
intermediate 7, which can readily lactonizes to give 9 upon alkylation
and displacement of an ROH molecule (Scheme 2). N-Alkylation pro-
cess meets a well documented analogy in the reaction of Horner reagent
with quinonimines,11 pyrroles,12a nitrosonaphthols,12b and oximes.4b
It was reported3a that phosphite esters attack 4-thiazolidinones 1,
preferably, at the exocyclic ethylene bond by 1:2 addition to give the
corresponding phosphorylated compounds. On the other hand, the for-
mation of a fused pyrone as described in Scheme 2 parallel the reac-
tions of 5-alkylidene thiazolidine-2,4-thiones with alkenes.13a Further-
more, we have reported13b an analogous mechanism for the reaction of
5-arylidinerhodanines 1b,c with alkylidenephosphorane counterparts
3a,b (Scheme 3).
Thus, by applying alkoxycarbonylmethylenetriphenylphosphoranes
3a,b on 1b,c in refluxing ethyl acetate, and in the presence of tri-
ethylamine (TEA), conjugated dihydrofuro[2,3-d]-thiazole-2H-thiones
A (∼46%) together with the diolefins B (∼18%) were isolated.
Carrying out the reaction in refluxing toluene, and also in the presence
of TEA, led to the formation of the fused pyrone derivative C (∼52%)
and B (∼11%).
Obviously, the mechanisms outlined in Schemes 2 and 3 show a sim-
ilar initial attack for the phosphonyl and phosphorane ylides 2 and
3. However, the transformations are quite different. The main differ-
ence between the present reaction and the corresponding one of the
Wittig reagents with the same substrate 1b13c is that, in the latter
case, the formation of the products is accompanied by elimination of
the phosphorus moiety. The contrasting behavior of the initial inter-
mediate through elimination “of the phosphorus moiety” is because
Ph3P is a much better leaving group than [(EtO)2PO−]. There is much
precedence for this difference.7 The results also showed the activated

1312
W. M. Abdou and M. D. Khidre
carbon-carbon double bond is a preferable site of attack by the phos-
phorane ylides, whereas the thiocarbonyl group is the preferable one
with phosphonyl carbanions.
Next, we investigated the reaction of 1a,b with diethyl
cyanomethylenephosphonate (2c). In contrast to the transformations
described above, when 1a,b and 2c (three-fold molar excess compared
to 1) reacted in boiling dimethylformamide (DMF) containing LiH
(2 equiv., compared to 2c), conjugated products 11a,b (∼27% yield)
and the fused-thiazole derivatives 12a,b (∼40% yield) were obtained.
Elemental analyses and spectral data substantiated the chemical
structures of 11 and 12. The 1H NMR spectra of the compounds 11a,b
showed a sharp singlet of the NH proton at ∼9.44. There were still
three types of CH protons [δ (Ha) ∼ 2.8 ppm (dd (m), 1H), δ(Hb) ∼3.5
ppm (dd (m), 1H) and δ(Hc) ∼ 4.5 (dd, (m), 1H)]. The C(O) carbon signal
in the 13C NMR spectra was observed at δc 161–163 ppm, while the
carbon atom of the CN group was shown at about 117 ppm. The 1-C
atom gave a doublet at about 44 ppm (1 J ∼ 136 Hz). The C(S)-carbon
C.P
signal in the 13C NMR spectra was observed by 192–194 ppm. In the
IR spectra of 11, the CN-group was located at 2220, 2218 as a weak
band and the thione-function was given at ∼1190 cm−1 as a strong
sharp band.
The 1H NMR spectrum of 12a (δp = 24.16 ppm) showed two types of
the NH2-protons [δ(Ha) = 6.55 (sbr, 1H) and δ(Hb) = 9.71 (s br., 1H)].
The different chemical shifts of the NH2-protons are the spectroscopic
evidence for the presence of intramolecular hydrogen bonds between
one of the hydrogens of the NH2-protons and the oxygen atom of the
P O bonding in the phosphonate group. The 2-C atom in the 13C NMR
appeared as a doublet at 97.2 (1 J = 196.3 Hz). Compounds 12 were
C,P
presumably formed through the attack of sulfur on 2c to generate the
intermediate B via the intermediate A. Subsequent cyclisation and
transformation of the cyano group led directly to the formation of fused
thiazole derivative 12 (Scheme 4). Obviously, the driving force for the
latter step can be attributed to the substitution on the methine carbon
atom with electron withdrawing thiol-, cyano- and phosphonato-groups,
which results in an increased acidity of the corresponding methine pro-
ton. Similar observation has been previously reported.14
Treatment of 1 with diethyl vinylphosphonate (2d) in DMF, in the
presence of LiH, yielded the phosphonates 13 (∼43% yield) and the
S-alkylated products 14a,b (∼26 yield) (Scheme 5). The product 14b
is, however, identical, in all aspects, to the known15 5-benzylidine-2-
(ethylthio)thiazolidin-4-one. Obviously, compound 13 is the product of
addition of the electron rich thioxo S-atom of either 1a,b or its conjugate
base on the electrophilic beta position of O,O-diethyl vinylphosphonate

Phosphono Substituted O-, and N-Heterocycles
1313
SCHEME 4
2d (which behaves like an unsaturated carboxylic ester), as has been
previously discussed.1b,16 On the other hand, 14a,b resulted from direct
alkylation (using the ethyl phosphonate as the alkylating agent) on the
sulfide anion intermediate −S−1A that resulted from treatment of 1a,b
with LiH. This type of alkylation is well known in organophosphorus
chemistry.8,9
SCHEME 5

1314
W. M. Abdou and M. D. Khidre
CONCLUSION
The results of the present and the previous work13b point out the variety
of reaction pathways, which can follow an initial attack of phosphorus
ylides 2 and 3 to C S and the exocyclic-C C groups in 5-arylidine-2-
thioxothiazolidin-4-ones 1a–b. Desulfuration process is also observed
in some products (see 8, Scheme 2 and B, Scheme 3). Finally, the present
work describes an efficient and simple approach to the synthesis of a va-
riety of condensed phosphono substituted O-, N-, and S-heterocycles in
reasonable yields. This general method consists of suitable applications
of the appropriate phosphonyl carbanion to thiazolidinones. Data on the
pharmaceutical potency of the new compounds 5, 8–10, and 11–13 will
be published elsewhere.
EXPERIMENTAL
Melting points are uncorrected. Infrared spectra were measured with
1
a Perkin-Elmer IR-spectrometer Model 597 using KBr discs. The H
and 13C NMR spectra were recorded with a Bruker Model WH-270
MHz spectrometer. The 31P NMR spectra were run on a Varian CFT-20
relative to external H3PO4. Mass spectra were performed at 70 eV on
a Schimadzu GCS-QPEX spectrometer provided with a data system.
All reactions were carried out under strictly moisture and oxygen free
conditions. Light petroleum refers to the fraction 40–60◦C.
I. Treatment of 5-Arylmethylene-2-thioxothiazolidinones
1a,b with Diethyl Phosphonoacetates (2a,b)
(A) Preparation of 5a
A 6 molar solution of sodium ethoxide (NaOEt) in absolute ethyl
alcohol solution (25 mL) was treated with a 3 molar solution of
methyl diethyl phosphonoacetate (2a) and then 4-thiazolidinone 1a18
(0.8 g, 3 mmol, 1 molar amount) was added. The resulting reac-
tion mixture was kept stirring for 3 days at room temperature.
The product mixture was concentrated and diluted with a small
amount of distilled water followed by solvent extraction (CHCl3) and
drying. Then the solvent was evaporated in the presence of 7 g
(Kieselgel 60, particle size 0.2–0.5 mm; E. Merck, Darmstadt) and
packed with n-hexane. Elution with hexane/CHCl3 (8:2, v/v) afforded
red crystals of diethyl [5-(4ꢁ-dimethylaminophenylmethylene)-3,4-dioxo-
3,4H-6,8-thiazolo-[8,7-c]-2,7-dihydro-1,8-thiazol]-2-yl-phosphonate (5a)
(0.7 g, 52%), m.p. 168–170◦C (from MeCN). (Found: C, 48.74; H, 5.18;

Phosphono Substituted O-, and N-Heterocycles
1315
N, 6.25; P, 7.12; S 14.41. C18H23N2O5PS2 requires C, 48.85; H, 5.24; N,
6.33; P, 7.00; S, 14.49%); νmax(KBr)cm−1 1698, 1690 (3-C O & 4-C O),
1622 (C C, exocyclic), 1245 (P O), 1100 (P O C); δH(270 MHz; CDCl3):
1.08, 1.32 (6H, 2dt, JH−H 6.6, 4 JH−P 3.8, H C C O), 3.06, 3.08 [6H, 2s,
3
3
(H C)2N], 4.16, 4.24 (4H, 2dq, JH−H 6.6, JH−P 4.6, 2 × H CO), 4.48
3
2
(1H, dd, JH−P 17.5, 2-CHP), 5.13 (1H, dd, JH−H 2.7, JH−P 4.4, 7-C H),
7.36 (2H, m, H−C6H4), 7.61 (2H, m, H−C6H4), 7.79 (1H, s, 5-C CH);
δC(270 MHz; CDCl3): 14.6, 15.2 (2CH3-C O), 31.2, 35.4 [(CH3)2N], 48.8
(d, J
187.8, 2-C P), 55.7 (7-C), 61.2, 62.5 (2 × CH2O), 120.9, 122.4,
C−P
126.4, 131.7 (6C, C6H4), 158.2, 161.5 (2 × C O); δP(CDCl3) 19.4 ppm;
m/z (EI) (%): 442 (M+ (36), requires 442.5), 427 (13), 414 (10), 398 (22),
386 (30), 305 (55), 252 (100). The second fraction (1:1, v/v) afforded
red leaflets of unchanged substrate 1a (180 mg, 22%), m.p. 285–288◦C
(EtOH) (Lit.,17 m.p. 285◦C); m/z (%) found 264 (100) C12H12N2OS2 re-
quires 264.36. Similarly, the reaction of triethyl phosphonoacetate (2b)
with thiazolidinone 1a was performed at r.t. for 3 days in ethanol con-
taining NaOEt, whereby the procedure was the same with 2a using the
same amounts. After the usual workup, phosphonate 5a (660 mg, 50%),
m.p. 168–170◦C (MeCN) was isolated and was shown to be identical to
material prepared above on using 2a.
(B) Preparation of 5b
A mixture of 1b18 (0.8 g, 3.62 mmol) and the appropriate Wittig-
Horner synthon 2a or 2b (∼10 mmol) in absolute EtOH (25 mL) con-
taining NaOEt (∼20 mmol) was stirred for 3 days at r.t. After the
usual workup, the product residue was column chromatographed (silica
gel/hexane with increasing amounts of CHCl3 to give, in each case, only
5b along with unchanged 1b (∼20%). Diethyl (5-benzylidene-3,4-dioxo-
3,4H-6,8-thiazolo[8,7-c]-2,7-dihydro-1,3-thiazol-2-yl-phosphonate (5b)
was obtained (8:2, v/v) as yellow crystals (830 mg, 58%), m.p. 146–
148◦C (from benzene). (Found: C, 48.18; H, 4.46; N, 3.43; P, 7.87; S,
16.12. C16H18NO5PS2 requires C, 48.11; H, 4.54; N, 3.51; P, 7.75; S,
16.05%); νmax(KBr)/cm−11700, 1687 (3-C O & 4-C O), 1628 (C C, ex-
ocyclic), 1240 (P O), 1105 (P O C); δH(270 MHz; CDCl3): 1.09, 1.32
(6H, 2dt, JH−H 6.6, JH−P 3.6, 2 × H C C O), 4.17, 4.24 (4H, 2dq, JH−H
3
6.6, JH−P 4.4, 2 × H CO), 4.58 (1H, dd, JH−H 2.4, JH−P 15.8, 2-CH P),
2
5.16 (1H, dd, JH−H 2.4, JH−P 4.4, 7-C H), 7.36 (3H, m, H−C6H5), 7.61
(2H, m, H−C6H5), 7.78 (1H, s, 5-C CH); δC(270 MHz; CDCl3): 14.3,
15.7 (2CH3-C O), 48.4 (d, J
187.8, 2-C P), 56.5 (7-C), 61.3, 62.4 (2
C−P
× CH2O), 120.3, 121.8, 124.6, 131.8 (6C, C6H5), 159.1, 160. (2 × C O);
δP (CDCl3) 20.1 ppm; m/z (EI) (%): 399 (M+(36), requires 399.43), 397
(44), 371 (18), 343 (32), 262 (100).

1316
W. M. Abdou and M. D. Khidre
(C) Preparation of 8a,b, 9a, and 5a
A mixture of 1a (0.8 g, 3 mmol) and 2a or 2b (9 mmol) in absolute
EtOH containing NaOEt (∼20 mmol) was refluxed for 24 h. After the
usual workup, the residue was chromatographed with hexane/CHCl3
to give 8a, 5a, and 9a or 8b, 5a, and 9a respectively.
i. With 2a. Dimethyl 2-[(5-(4-dimethylaminophenylmethylene)-4-
oxo-4H-1,3-thiazole]-1,2-ethylenedicarboxylate (8a) was obtained (9:1,
v/v) as red crystals (400 mg, 30%), m.p. 110–112◦C (from diethyl ether).
(Found: C 57.82, H 4.07, N 7.43, S 8.67. C18H18N2O5S requires C 57.74,
H 4.85, N 7.48, S 8.56%); νmax(KBr)/cm−11705–1692w (3 × C O), 1618,
1634 (2 × C C, exocyclic); δH(270 MHz; CDCl3): 2.99, 3.01 [6H, 2s,
(H C)2N], 3.84, 3.92 (2 × 3H, 2s, 2 × H CO2C), 6.97 (s, 1H, HC CO2Me),
3
3
7.39 (2 × 2H, 2m, H−C6H4), 7.56 (2H, m, H Ar), 7.78 (1H, s, HC Ar);
δC(270 MHz; CDCl3): 30.8, 35.8 [(CH3)2N], 53.4, 55.1 (2 × CH3O, es-
ters), 98.7 ( CHCO2Me), 120.6, 122.8, 126.8, 131.7 (6C, C6H4), 135.3
(2-C),141.2 ( CHAr), 159.3, 160.1, 162.6 (3 × C O); m/z (EI) (%): 374
(M+,(22), requires 374.42), 359 (11), 344 (18), 331 (50), 330 (68), 316
(9), 288 (33), 232 (100), 77 (10). The next fraction (8:2, v/v) afforded red
crystals of 5a (170 mg, 13%), m.p. 168–170◦C (from MeCN), identical
with the material prepared as described above.
The third fraction (7:3, v/v) yielded orange needles of 2-thioxo-2,
H-N-ethyl-1,3-thiazolo-[8,9-b]-7-(4ꢁ-dimethylaminophenyl)-5-oxo-5H-6,
7-dihydropyran-6-yl)phosphonic acid diethyl ester (9a) (410 mg, 29%),
m.p. 144–146◦C (from cyclohexane). (Found: C 51.13, H 5.72, N 5.83,
P 6.64, S 13.57. C20H27N2O5PS2 C, 51.05; H, 5.78; N, 5.95; P, 6.58;
S, 13.62 %); νmax(KBr)/cm−1 1738 (C O, pyrone), 1180 (C S), 1066
(P O C); δH(270 MHz; CDCl3): 1.48 (3H, t, JH−H 6.9, H C C N),
3
1.12,1.27 (6H, 2t, JH−H 6.5, JH−P 4.82, H C C O P), 2.98, 3.01
3
[6H, 2s, (H C)2N], 4.13, 4.24 (4H, 2dq, JH−H 6.6, JH−P 5.2 Hz, 2 ×
3
H CO), 4.56 (2H, q, JH−H 6.9, H CN), 5.15 (1H, d, JH−P 4.6, JH−P 16.6,
2
2
6-CH−P), 5.36 (1H, dd, JH−H 4.6, JH−P 4.8, 7-CH Ar), 7.24, 7.67 (2
× 2H, 2m, H C6H4); δC(270 MHz; CDCl3): 11.6, 15.5, 16.2 (CH3-C.N,
CH3-C O P), 30.2, 34.8 [(CH3)2N], 46.8 (7 C), 51.2 (CH2.N), 62.5
(CH2O), 73.1 (d, JC−P196.3, 6-CH-P), 112.9, 118.6,126.4, 131.7 (6C,
C6H4), 128.5 (8-C), 155.2 (9-C), 175.4 (C O, pyrone), 193.2 (C S);
δP(CDCl3) 21.3 ppm; m/z (EI) (%): 470 (M+(16), requires 470.55) 468
(38), 440 (8), 439 (21), 436 (15), 424 (66), 331 (100), 287 (73).
ii. With 2b. Diethyl 2-[(5-(4ꢁ-dimethylaminophenylmethylene)-4-oxo-
4H-1,3-thiazole]-1,2-ethylenedicarboxylate (8b) was obtained (9:1, v/v)
as red crystals (460 mg, 28%), m.p. 102–104◦C (from pentane). (Found:
C 59.77, H 5.57, N 6.88, S 7.98. C20H22N2O5S requires C 59.69, H 5.51,
N 6.96, S 7.96%]; νmax(KBr)/cm−1 1700–1696 (3 × C O), 1628, 1632

Phosphono Substituted O-, and N-Heterocycles
1317
(2 × C CHAr); δH (270 MHz; CDCl3): 0.85, 0.88 (2t, 6H, JH−H = 6.5 Hz,
H C C O, esters), 2.97, 3.02 [6H, 2s, (H C)2N], 3.82, 3.96 (2 × 2H,
3
3
2q, JH−H 7.2, H CO, esters), 7.0 (s, 1H, HC CO2Et), 7.29 (2H, m,
3
H−C6H4), 7.56 (2H, m, H−C6H4), δC(270 MHz; CDCl3): 13.8, 15.2 (CH3-
C O, esters), 31.3, 36.2 [(CH3)2N], 55.3, 57.6, (2 × CH2O, esters), 103.7
( CHCO2Et), 121.3, 124.2, 126.4, 131.4 (6C, C6H4), 136.3 (2 C), 138.7
( CHAr), 158.7, 160.4, 162.3 (3 × C O); m/z (EI) (%): 402 (M+ (45),
requires 402.47), 383 (13), 359 (42), 354 (20), 292 (60), 232 (100), 77
(17).
The second fraction (8:2, v/v) yielded red crystals of 5a (180 mg,
14%), m.p. 168–170◦C (MeCN), and shown to be identical with the ma-
terial that obtained before. The third fraction (7:3, v/v) gave orange
needles, which shown to be 9a (425 mg, 30%), m.p. 144–146◦C (from
cyclohexane).
(D) Preparation of 8c,d, 9b, and 5b
In the same manner, the reaction mixture of the appropriate carban-
ion 2a or 2b and 1b (0.8 g, 3.6 mmol) was heated at reflux temperature
for 24 h; the procedure and the workup were the same (with 1a) using
the same amounts. The residue was purified by chromatography on sil-
ica gel using hexane-CHCl3 to give compounds 8c, 5b, and 9b or 8d,
5b, and 9b respectively.
i. With 2a. Dimethyl 2-[(5-(phenylmethylene)-4-oxo-4H-1,3-thiazole]-
1,2-ethylene-dicarboxylate (8c) was obtained (9:1, v/v) as yellow crystals
(560 mg, 33%), m.p. 103–105◦C (from light petroleum). (Found: C 58.16,
H 3.89, N 4.11, S 9.69. C16H13NO5S requires C 58.00, H 3.95, N 4.23,
S 9.67%]; νmax(KBr)/cm−1 1715, 1705, 1695 (3 × C O), 1616, 1630 (2 ×
C C, exocyclic); δH(270 MHz; CDCl3): 3.61, 3.64 (2 × 3H, 2s, 2 × H CO,
3
esters), 7.07 (s, 1H, HC CO2Me), 7.32 (3H, m, H−C6H5), 7.64 (2H,
m, H−C6H5), 7.79 (1H, s, HC Ph); δC(270 MHz; CDCl3): 53.4, 55.1
(2 × CH3O,esters), 112.3 ( CHCO2Et), 120.6, 122.8, 126.8, 131.7 (6C,
C6H5), 136.8 (2-C), 141.5 ( CHAr), 159.3, 160.1, 162.2 (3 × C O); m/z
(EI) (%): 331 (M+(28), requires 331.35), 316 (12), 301 (25), 273 (19), 254
(48), 245 (16), 189 (100). The second fraction (8:2, v/v) yielded yellow
crystals of 5b (145 mg, 10%), m.p. 146–148◦C (from benzene).
The third fraction (7:3, v/v) gave yellow crystals of 2-thioxo-2,H-
N-ethyl-1,3-thiazolo-[8,9-b]-7-phenyl)-5-oxo-5H-6,7-dihydropyran-6-yl)
phosphonic acid diethyl ester (9b) (420 mg, 27%), m.p. 118–120◦C
(from cyclohexane). (Found: C, 50.63; H, 5.11; N, 3.16; P, 7.29; S, 15.07.
C18H22NO5PS2 requires C, 50.57; H, 5.19; N, 3.27; P, 7.25; S, 15.0%];
νmax(KBr)/cm−1 1735 (C O, pyrone), 1245 (P O), 1190 (C S), 1080
(P O C); δH(270 MHz; CDCl3): 0.89 (3H, t, JH−H 6.9, H C C N),
3

1318
W. M. Abdou and M. D. Khidre
4
1.12, 1.26 (6H, 2t, JH−H 6.5, JH−P 4.1, H C C O P), 4.12, 4.23 (4H,
3
2q, JH−P 10.2, H C O P), 4.75 (q, 2H, JH−H 6.9, H C N), 5.23 (1H,
2
2
d, JH−P 4.6, JH−P 16.6, 6-CH−P), 5.39 (1H, dd, JH−H 4.6, JH−P 4.8,
7-CH Ar), 7.38 (3H, m, H−C6H5), 7.64 (2H, m, H−C6H5); δP (CDCl3)
16.8 ppm; m/z (EI) (%): 427 (M+(15), requires 427.48), 425 (41), 397
(8), 496 (23), 393 (13), 288 (100), 259 (61).
ii. With 2b. Diethyl 2-[(5ꢁ-(phenylmethylene)-4-oxo-4H-1,3-thiazole]-
1,2-ethylene-diacetate (8d) was obtained (9:1, v/v) as yellow crystals
(540 mg, 30%), m.p. 98–100◦C (from pentane). (Found: C 60.21, H
3.95, N 3.81, S 6.44. C18H17NO5S requires C 60.15, H 4.76, N 3.90,
S 8.92%); νmax(KBr)/cm−1 1717, 1710, 1700 (3 × C O), 1616, 1624
(2 × C C, exocyclic); δH(270 MHz; CDCl3): 0.86, 0.92 (6H, 2t, JH−H
6.9,H C C O, esters), 3.85, 3.87 (4H, 2q, JH−H 6.9, H CO, esters), 7.12
3
2
(s, 1H, HC CO2Et), 7.36 (3H, m, H−C6H5), 7.6 (2H, m, H−C6H5), 7.78
(1H, s, HCPh); δC (270 MHz; CDCl3): 14.3, 15.2 (CH3-CO, esters), 54.6,
56.2 (2 × CH2O, esters), 112.3 ( CHCO2Et), 121.3, 124.4. 126.4, 131.7
(6C, C6H5), 137.1 (2-C), 139.3 ( CHAr), 158.6, 159.4, 162.5 (3 × C O);
m/z (EI) (%): 359 [M+ (20), requires 359.4), 330 (27), 301 (14), 272 (21),
254 (18), 245 (41), 189 (100), 77 (14).
The second fraction (8:2, v/v) afforded yellow crystals of 5b (216 mg,
15%), m.p. 146–148◦C (MeCN), identical with the material prepared as
described above, on using 2a.
The third fraction (7:3, v/v) gave yellow leaflets, which shown to be
9b (430 mg, 28%), m.p. 118–120◦C (from cyclohexane).
Conversion of 9a,b to 10a,b
N-Bromosuccinimide (NBS) (54 mg, 0.3 mmol) and benzoyl per-
oxide (7 mg, 0.04 mmol) were added to a solution of 9a (100 mg,
0.21 mmol) or 9b (100 mg, 0.23 mmol) in 20 mL of dry CCl4. The
mixture was refluxed for ∼3h (TLC) and filtered while hot. Evapora-
tion of the solvent left a residue, which was triturated with a small
amount of light petroleum to give the corresponding dehydrogenated
derivative, 10a or 10b. 2-thioxo-2,H-N-ethyl-1,3-thiazolo-[9,8-b]-7-(4ꢁ-
dimethylaminophenyl)-5-oxo-5H-pyran-6-yl) phosphonic acid diethyl
ester (10a) (62 mg, 62%), m.p. 128–130◦C (from cyclohexane). (Found:
C, 51.36; H, 5.31; N, 5.88; P, 6.69; S, 13.73. C20H25N2O5PS2 C, 51.27; H,
5.38; N, 5.98; P, 6.61; S, 13.69%); νmax(KBr)/cm−1 1742 (C O, pyrone),
1265 (P O), 1185 (C S), 1068 (P O C); δH(270 MHz; CDCl3): 0.86
(3H, t, JH−H 6.9, H C C N), 1.13, 1.27 (6H, 2t.br, JH−H6.9, JH−P 4.5,
3
H C C O P), 2.97, 3.02 [6H, 2s, (H C)2N], 4.13, 4.24 (4H, 2dq, JH−P
3
3
11.5, H C O P), 4.66 (2H, q, JH−H 6.9, H C N), 7.26, 7.65 (2 × 2H,
2
2
2m, H C6H4); δP(CDCl3) 22.5 ppm; m/z (EI) (%): 468 (M+ (34), requires
468.54), 440 (9), 439 (23), 436 (14), 424 (61), 331 (100), 287 (76).

Phosphono Substituted O-, and N-Heterocycles
1319
2-Thioxo-2,H-N-ethyl-1,3-thiazolo-[8,9-b]-7-phenyl-5-oxo-5H-pyran-
6-yl) phosphonic acid diethyl ester (10b) (60 mg, 60%), m.p. 112–114◦C
(light petroleum). (Found: C, 50.72; H, 4.66; N, 3.14; P, 7.34; S, 15.13.
C18H20NO5PS2 requires C, 50.81; H, 4.74; N, 3.29; P, 7.28; S, 15.07%];
νmax(KBr)/cm−1 1748 (C O, pyrone), 1247 (P O), 1185 (C S), 1090
(P O C); δH(270 MHz; CDCl3): 0.87 (3H, t, JH−H 6.9, H C C N),
3
1.12, 1.27 (6H, 2t, JH−H 6.5, JH−P 4.5, H C C O P), 4.12, 4.23 (4H,
3
2q, JH−P 11.5, H COP), 4.74 (2H, q, JH−H 6.9, H C N), 7.38 (3H, m,
2
2
H−C6H5), 7.64 (2H, m, H−C6H5); δP(CDCl3) 17.3 ppm; m/z (EI) (%):
425 (M+(44), requires 425.47), 397 (10), 396 (30), 393 (18), 288 (100),
259 (58).
II. Reaction of 4-Thiazolidinones 1a,b with Diethyl
α-cyanomethylphosphonate (2c)
General Procedure
To a slurry of ∼1 g of LiH (60% in mineral oil, washed with pentane)
in a stirred solution of DMF (20 mL) was added dropwise a solution
of the phosphonate 2c (1.8 g, ∼10 mmol) in 10 mL of DMF. After the
evolution of H2 had ceased, the suspension was stirred at r.t. for further
20 min and then refluxed for 1 h. The reaction mixture was cooled to
r.t., and the substrate 1a (0.8 g, 3 mmol) or 1b (0.8 g, 3.62 mmol) was
introduced all at once and the reaction mixture was refluxed for 24–
36 h. The product mixture was then concentrated and the excess of LiH
was quenched carefully with ice water (30 mL) followed by acidification
with conc. HCl, solvent extraction (CHCl3), drying and evaporation.
Column chromatography (silica gel/hexane with increasing amounts of
CHCl3 and then recrystallization of the crude product mixture gave the
pure products 11a and 12a or 11b and 12b respectively.
2-[5-(4-oxo-2-thioxo-2,4H-1,3-thiazolo)]-1-cyano-2-(dimethylamino-
phenyl)-ethylen-1-yl-phosphonic acid diethyl ester (11a) was obtained
(7:3, v/v) as yellow crystals (400 mg, 30%), m.p. 170–172◦C (CH2Cl2).
(Found: C, 48.86; H, 5.42; N, 9.47; P, 7.08; S, 14.47. C18H24N3O4PS2
requires C, 48.97; H, 5.48; N, 9.52; P, 7.02; S, 14.52%]; νmax(KBr)/cm−1
3200 (NH), 2222 (CN), 1700 (C O), 1255 (P O), 1192 (C S), 1085
(P O C); δH(270 MHz; CDCl3): 1.11, 1.24 (6H, 2dt, JH−P 10.2,
H C C O), 2.82 (1H, dd(m), J 7, 12, HaC P), 2.96, 2.99 [6H, 2s,
3
(H C)2N], 3.42 (1H, dd(m), J 7, 4, HbC Ar), 4.08, 4.13 (4H, 2q,
3
JH−P11.8, H COP), 4.63 (1H, m, CHc), 7.36 (2H, m, H−C6H4),
2
7.61 (2H, m, H−C6H4), 9.48 (1H, sw, HN); δC(270 MHz; CDCl3):
15.3, 16.5 (CH3-C O P), 31.2, 36.3 [(CH3)2N], 44.6 (d, J
136.5,
C−P
CHa(CN) P), 46.2 (CHb Ar), 48.9 (CHc), 108.2 [C(CN)], 117.6 [(CN)C],
120.7, 122.2, 127.6, 131.9 (6C, C6H4),160.3 (4-C O), 190.8 (C S); δP

1320
W. M. Abdou and M. D. Khidre
(CDCl3) = 22.7 ppm; m/z (EI) (%): 441 (M+ (14), requires 441.51), 414
(51), 412 (33), 397 (53), 370 (62), 277 (51), 275 (100), 231 (67).
2-[(4ꢁꢁ-dimethylaminophenyl)methylene]-3-oxo-1,3-thiazolo-[5,4-b]-
3ꢁ-amino-1ꢁ, 3ꢁ-thiazol-2ꢁ-yl phosphonic acid diethyl ester (12a) was
obtained (6:4, v/v) as orange crystals (440 mg, 33%), m.p. 212–214◦C
(from cyclohexane). (Found: C, 48.99; H, 5.38; N, 9.47; P, 7.08; S, 14.58.
C18H24N3O4PS2 requires C, 48.97; H, 5.48; N, 9.52; P, 7.02; S, 14.52%];
νmax(KBr)/cm−1 3240w (NH2), 1700 (C O), 1628 ( CH, exocyclic),
1225 (P O), 1126 (P O C); δH(270 MHz; CDCl3): 1.14, 1.31 (6H, dt,
JH−H 6.2, JH−p 4.2, H C CC O), 2.97, 3.05 [6H, 2s, (H C)2N], 4.05,
3
3
4
4.27 (4H, 2q, JH−p 11.2, H CO), 4.88 (1H, d, JH−P 2.8, 7-CH), 6.55
2
(1H, brs, HaN, NH2), 7.39 (2H, m, H−C6H4), 7.56 (2H, m, H−C6H4),
7.82 (1H, s, CHAr), 9.71 (1H, brs, HbN,NH2); δC(270 MHz; CDCl3):
14.8 (CH3C O), 30.4, 34.6 [(CH3)2N], 52.6 (7-C), 63.5 (CH2O), 97.2
(d, 1 J
196.3, 2ꢁ-C P), 120.9, 122.1, 126.7, 133.2 (6C, C6H4), 156.4
C−P
(3ꢁ-C NH2), 162.9 (4-C O); δP(CDCl3) 24.16 ppm; m/z (EI) (%): 441
(M+ (42), requires 441.51), 435 (9), 413 (13), 397 (40), 304 (100), 260
(61).
2-[5-(4-oxo-2-thioxo-2,4H-1,3-thiazolo)]-1-cyano-2-phenylethylen-1-
yl-phosphonic acid diethyl ester (11b) was obtained (8:2, v/v) as pale
yellow crystals (360 mg, 25%), m.p. 152–154◦C (from light petroleum).
(Found: C, 48.31; H, 4.75; N, 6.97; P, 7.66; S, 16.13. C16H19N2O4PS2
requires C, 48.23; H, 4.81; N, 7.03; P, 7.77; S, 16.09%]; νmax(KBr)/cm−1
3230 (NH), 2218 (CN), 1696 (C O), 1256 (P O), 1100 (P O C); δH(270
MHz; CDCl3): 1.09, 1.2 (6H, 2dt, JH−P 10.5, H C C O P), 2.78 (1H,
3
dd, J 7, 12, HaC P), 3.64 (1H, dd, J 7, 4, HbC Ar), 4.12, 4.22 (4H, 2q,
JH−P 11.8, H C O P), 4.82 (1H, m, CHc), 7.36 (3H, m, H−C6H5),
2
7.61 (2H, m, H−C6H5), 9.44 (1H, sw, HN); δP(CDCl3) 22.1 ppm; m/z
(EI)(%): 398 (M+ (18), requires 398.44), 371 (48), 369 (40), 261 (100),
234 (64), 233 (68).
2-[(4ꢁꢁ-dimethylaminophenyl)methylene]-3-oxo-1,3-thiazolo-[5,4-b]-
3ꢁ-amino-1ꢁ, 3ꢁ-thiazol-2ꢁ-yl phosphonic acid diethyl ester (12b) was
obtained (7:3, v/v) as yellow needles (575 mg, 40%), m.p. 178–180◦C
(from cyclohexane). (Found: C, 48.14; H, 4.73; N, 7.12; P, 7.63; S, 16.02.
C16H19N2O4PS2 requires C, 48.23; H, 4.81; N, 7.03; P, 7.77; S, 16.09%];
νmax(KBr)/cm−1 3240w (NH2), 1698 (C O), 1620 (C C, exocyclic), 1235
(P O), 1050 (P O C); δH(270 MHz; CDCl3): 1.12, 1.25 (6H, dt, JH−H
6.5, JH−P 4.3, H C C O), 4.13, 4.24 (4H, 2q, JH−P 11.8, H CO), 4.79
3
2
(1H, d, JH−P 2.7, 7-CH), 6.64 (1H, brs, HaN, NH2), 7.36 (3H, m,
H−C6H5), 7.61 (2H, m, H−C6H5), 9.72 (1H, sw, HbN, NH2); δP(CDCl3)
23.7 ppm; m/z (EI) (%): 398 (M+ (28), requires 398.44), 382 (13), 370
(19), 261 (100), 244 (22).
4

Phosphono Substituted O-, and N-Heterocycles
1321
III. Reaction of 4-Thiazolidinones 1a,b with Diethyl
Vinylphosphonate (2d)
A solution of the Wittig-Horner reagent 2d (1.1 g, ∼7 mmol) and 1a
(0.6 g, 2.3 mmol) or 1b (0.5 g, 2.3 mmol) in DMF (30 mL) was treated with
LiH (500 mg) at r.t., and the system was further refluxed for 12 h. The
reaction mixture was worked up as described for the reaction with 2c
and separated by column chromatography using hexane/CHCl3 as the
eluents to give the products 13a and 14a or 13b and 14b respectively.
5-(4ꢁ-Dimethylamino-phenylmethylene)-2- (ethylthio)-1,3-thiazol-4-
one (14a) was obtained (9:1, v/v) as orange crystals (155 mg, 28%),
m.p. 98–100◦C (from cyclohexane) (Lit.14 m.p. 98◦C), m/z (EI) (%): 292
(M+ (68), requires 292.42), 264 (100), 221 (67).
The phosphonate 13a was obtained as yellow crystals (350 mg, 44%),
m.p. 198–200◦C (from acetone). (Found: C, 50.52; H, 5.82; N, 6.47; P,
7.35; S, 14.56. C18H25N2O4PS2 requires C, 50.45; H, 5.88; N, 6.54; P,
7.23; S, 14.96%]; νmax(KBr)/cm−1 1700 (C O), 1628 (C C), 1350 ( S C),
1255 (P O), 1100 (P O C); δH(270 MHz; CDCl3): 1.09, 1.22 (6H, 2dt,
JH−H 7.2, JH−P3.5, H C C OP), 2.26 (2H, dt, 1 JH−P 18.5, H CP), 3.05,
3
2
3
3.58 [6H, 2s, (H C)2N], 3.37 (2H, dt, JH−P12, H C.S), 4.15, 4.22 (4H,
3
2
2dq, JH−H 7.2, JH−P 4.8, H COP), 7.37 (2H, d, JH−H 7.2, H−C6H4),
2
7.41 (2H, d, JH−H 7.2, H−C6H4), 7.82 (1H, s, HCAr); δC(270 MHz;
CDCl3): 15.3, 16.1 (2 × CH3C O), 22.8 (d, J
142.5, CH2 P), 29.2
C−P
(CH2S), 31.4, 33.7 [(CH3)2N], 60.4, 61.2 (CH2O.P), 120.6, 124.9, 126.7,
128.7 (6C,C6H4), 139.7 ( CHAr), 143.8 (5-C, Het), 151.3 (2-C, Het),
159.7 (C O); δP(CDCl3) 15.8 ppm; m/z(EI) (%): 428 (M+ (27), requires
428.51), 291 (55), 247 (32), 264 (100), 220 (60).
5-Benzylidene-2-(ethylthio)-1,3-thiazol-4-one (14b) was obtained
(9:1, v/v) as pale yellow needles (130 mg, 23%), m.p. 55–57◦C (from
pentane) (lit.15 m.p. 55◦C), m/z (EI) (%): 249 (M+ (56), requires 249.35),
221 (100), 199 (18).
The phosphonate 13b was obtained as pale yellow crystals (380 mg,
41%), m.p.155–157◦C (from benzene). (Found: C, 49.92; H, 5.29; N, 3.57;
P, 8.14; S, 16.34. C16H20NO4PS2 requires C, 49.86; H, 5.23; N, 3.63; P,
8.04; S 16.63%); νmax(KBr)/cm−1 1705 (C O), 1622 (C C), 1342 (S C),
1256 (P O), 1105 (P O C); δH(270 MHz; CDCl3): 1.11, 1.32 (6H, 2dt,
JH−P 10.5, H C C O), 2.31 (2H, dt, 3 JH−P 18.5, H C P), 3.34 (2H, dt,
3
2
JH−P 12, H C S), 4.17, 4.23 (4H, 2dq, JH−P = 11.7, H C O P), 7.35 (3H,
2
2
m, H−C6H5), 7.64 (2H, m, H−C6H5), 7.80 (1H, s, CHAr); δC(270 MHz;
1
CDCl3): 15.5, 16.1 (2 × CH3-C O), 24.3 (d, J
143.4, CH2-P), 28.8
C−P
(CH2-S), 60.4, 61.2 (CH2OP), 125.6, 129.2, 130.0, 137.7 (C C6H5), 141.7
( CHPh), 152.2 (2ꢁ-C,Het), 160.3 (C O, Het.); δP(CDCl3) 15.7 ppm; m/z
(EI) (%): 385 (M+ (30), requires 385.44), 248 (50), 221 (100).

1322
W. M. Abdou and M. D. Khidre
REFERENCES
[1] a) G. Tomlin, ed., in the Pesticide Manual (British Crop Protection Pub. Survey,
1991) 10th ed.; b) S. P. Singh, S. S. Parmar, K. Raman, and V. I. Stenberg, Chem.
Rev., 81, 175 (1981); c) G. Danila, Rev. Chem., (Bucharest), 29(12), 1152 (1978);
Chem. Abstr., 90, 152037 (1979).
[2] a) R. Y. Chen and L. Z. Liu, Chemistry of Organophosphorus Pesticides (Shanghai
Scientific and Technical Press, Shanghai, 1965); b) K. Issleib, Nachr. Chem. Tech.,
35, 1037 (1987).
[3] a) B. P. Lugovkin, Zh. Obshch. Khim., 48, 1529 (1978); Chem. Abstr., 89, 163673
(1978); b) B. E. Zhitar and S. N. Baranov, Tezisy Dokl-Simp. Khim. Tekhnol.,
(Geterotsikl Soedin. Goryuch. Iskop., 1973), 2nd ed., p. 202; Chem. Abstr., 85, 192820
(1979).
[4] b) W. M. Abdou, M. A. I. Salem, and R. F. Barghash, Synth. Commun., 33(8), 1341
(2003); b) W. H. Abdou, M. A. I. Salem, and R. F. Barghash, Synlett, 1417 (2002);
c) W. M. Abdou and A. A. Shaddy, Synth. Commun., 31, 13 (2001); d) W. M. Abdou
and N. A. Ganoub, Synth.,Commun., 28(19), 3579 (1998).
[5] P. D. Woodgate, Ho. H. Lee, P. S. Rutledge, and R. C. Camble, Synthesis, 322 (1977).
[6] a) P. M. Silverstein, G. C. Bassler, and T. C. Morril, Spectroscopic Identification of
Organic Compounds (Wiley and Sons, New York, 1981); b) G. C. Levy, R. L. Lichter,
and G. L. Nilson, Carbon-13 Nuclear Magnetic Resonance Spectroscopy (Wiley and
Sons, New York, 1981).
[7] a) E. Zbiral, Tetrahedron Lett., 5107 (1970); b) C. G. Krespan, J. Am. Soc., 83, 33434
(1961).
[8] a) E. Zbiral, in Organophosphorus Reagents in Organic Synthesis, edited by J. I.
G. Cadogen (Academic Press, London, 1979), 2nd ed., chap. 5, pp. 223–268; b)
W. M. Abdou and I. T. Hennawy, Phosphorus, Sulfur and Silicon, 89, 105 (1994);
c) W. M. Abdou and N. A. Ganoub, Phosphorus, Sulfur and Silicon, 105, 63 (1995).
[9] H. S. Masson, Main Group Chemistry News, 2, 18 (1994).
[10] L. S. Boulos and E. S. M. A. Yakout, Phosphorus, Sulfur and Silicon, 84, 35 (1993).
[11] M. Mercey and P. Toube, J. Chem. Res. Synop., 13 (1987).
[12] a) L. S. Boulos and M. H. N. Arsanious, Phosphorus, Sulfur and Silicon, 89, 185
(1994); b) L. S. Boulos, M. H. N. Arsanious, and N. K. Eldin, Phosphorus, Sulfur
and Silicon, 122, 49 (1997).
[13] a) A. A. Ead, S. O. Abdallah, N. A. Kassab, N. H. Metwalli, and Y. E. Saleh, Arch.
Pharm., 320, 1227 (1987); b) W. M. Abdou, E. S. M. A. Yakout, and N. A. F. Ganoub,
Tetrahedron, 51, 11411 (1995).
[14] a) R. Neidlein, M. Jochheim, C. Krieger, and W. Kramer, 39, 185 (1994); b) M. S.
Abbady and Sh. M. Radwan, Phosphorus, Sulfur and Silicon, 86, 203 (1994).
[15] S. M. Ramsh, G. S. Antonova, A. I. Ginak, and E. G. Sochilin, Zh. Org. Khim., 11(8),
1755 (1975); Chem. Abstr., 83, 193156 (1975).
[16] a) E. E. Schweizer and C. M. Kopay, J. Org. Chem., 37, 1561 (1972); b) R. Galli, J.
Org. Chem., 52, 5349 (1987).
[17] C. Lapiere, J. Pharm. Belg., 11, 3 (1956); Chem. Abstr., 51, 1940 (1957).
[18] I. T. Kashkaval, Farm. Zh. (Kiev), 21, 9 (1966); Chem. Abstr., 67, 64281 (1967).

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