1,2-Alkatrienephosphonates in the reactions with sulfenyl- and selenenylbromides

Article abstract of DOI:10.1080/10426500701340857

The interaction of 1,2-alkatrienephosphonic dichlorides and dialkyl esters with sulfenyl- and selenenylbromides is investigated and a possible mechanism of the reactions is discussed. The possibility to control the structure of the products by variation o

Full text of DOI:10.1080/10426500701340857

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Phosphorus, Sulfur, and Silicon
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1,2-Alkatrienephosphonates
in the Reactions with Sulfenyl-
and Selenenylbromides
Dobromir D. Enchev a & Stanimir P. Stankolov a
a Department of Organic Chemistry and Technology,
Faculty of Natural Sciences , K. Preslavsky
University , Shumen, Bulgaria
Published online: 15 Jun 2007.
To cite this article: Dobromir D. Enchev & Stanimir P. Stankolov (2007) 1,2-
Alkatrienephosphonates in the Reactions with Sulfenyl- and Selenenylbromides,
Phosphorus, Sulfur, and Silicon and the Related Elements, 182:8, 1857-1869, DOI:
10.1080/10426500701340857
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Phosphorus, Sulfur, and Silicon, 182:1857–1869, 2007
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500701340857
1,2-Alkatrienephosphonates in the Reactions with
Sulfenyl- and Selenenylbromides
Dobromir D. Enchev
Stanimir P. Stankolov
Department of Organic Chemistry and Technology, Faculty of Natural
Sciences, K. Preslavsky University, Shumen, Bulgaria
The interaction of 1,2-alkatrienephosphonic dichlorides and dialkyl esters with
sulfenyl- and selenenylbromides is investigated and a possible mechanism of the
reactions is discussed. The possibility to control the structure of the products by
variation of the type of the electrophile and of the substrate is also shown.
Keywords 1,2-Alkatrienephosphonates; selenenylbromides; sulfenylbromides
INTRODUCTION
1,2-Alkatrienephosphonates, i.e., 3- and 1-vinylsubstituted 1,2-
alkadienephosphonic dichlorides and esters, are interesting substrates,
containing both 1,2- and 1,3-dienic fragments in the alkatrienephos-
phonate system.1−9 These compounds react with different kinds
of electrophilic reagents to a variety of products: 2,5-dihydro-1,2-
oxaphosphole derivatives, phosphorus containing thiophenes and se-
lenophenes, as well as adducts.1−4,6−8,10−15 On the other hand, the in-
teraction of the dialkyl esters of alkatrienephosphonic acids with sulfur
dioxide affords cyclic sulphonephosphonates.11−13
Here, we report our results on the reactivity of the dichlorides and of
the dialkyl esters of 3-methyl-1,2,4-pentatrienyl-1- and 5-methyl-1,3,4-
hexatrienyl-3-phosphonic acids with sulfenyl- and selenenylbromides.
RESULTS AND DISCUSSION
The reaction of the dichlorides and of the dialkyl esters of 3-methyl-
1,2,4-pentatrienyl-1- and 5-methyl-1,3,4-hexatrienyl-3-phosphonic
Received June 20, 2006; accepted February 22, 2007.
Address correspondence to Dobromir Enchev, Department of Organic Chemistry and
Technology, Faculty of Natural Sciences, K. Preslavsky University, Shumen BG-9712,
Bulgaria. E-mail: rector@shu-bg.net
1857

1858
D. D. Enchev and S. P. Stankolov
acids with sulfenyl- and selenenylbromides is carried out in methy-
lene chloride at low temperature. As expected, the reactions lead
to phosphorylated thiophenes, phosphorylated selenophenes, and to
additional products (Scheme 1).
SCHEME 1
The structures of the products confirmed our expectation, that
3-methyl-1,2,4-pentatriene-1-phosphonic dichloride
1 reacts with
sulfenyl- and selenenylbromides with formation of a thiophene and
selenophene ring to afford the dichloride of (3-methylthiophen-
2-yl)methylphosphonic acid
2
and of (3-methylselenophen-2-
yl)methylphosphonic acid 3, respectively. The reaction of the dichloride
of 5-methyl-1,3,4-hexatriene-3-phosphonic acid 4 with phenylsulfenyl-
bromide leads to 1-bromo-5-methyl-4-phenylthio-2,4-pentadienyl-
3-phosphonic dichloride 5, while with phenylselenenylbromide
2-isopropyl-3-selenophenephosphonic dichloride the selenophene 6
was isolated.
The reaction of the 3-methyl-1,2,4-pentatriene-1-phosphonic acid di-
alkyl esters 7a–e with phenylsulphenyl- and phenylselenenylbromides
leads to the corresponding dialkyl esters of (3-methylthiophen-
2-yl)methylphosphonic acid 8a–e and (3-methylselenophen-2-
yl)methylphosphonic acid 9a–e, respectively (Scheme 2).
On the other hand, the reaction of dialkyl esters of 5-methyl-1,3,4-
hexatriene-3-phosphonic acid 10a–e with phenylsulphenylbromide

1,2-Alkatrienephosphonates
1859
SCHEME 2
leads to the corresponding oxaphospholes 11a–e and thiophenes 12a–e,
respectively. When the same dialkyl esters are reacted with phenylse-
lenenyl bromide cyclization to the vinyl-substituted 2,5-dihydro-1,2-
oxaphosphole derivatives 13a–e takes place (Scheme 3).
Compounds 3, 6, 9a–e, and 13a–e contain the isotope 77Se, which
is magnetically active and interacts with other nuclei. This interaction
becomes evident with the protons of the neighboring groups which ex-
hibit symmetric 77Se satellite signals on both sides of the main signal
in the 1H NMR spectra.22
SCHEME 3

1860
D. D. Enchev and S. P. Stankolov
SCHEME 4
Our previous investigations11−15 and the isolation of 2,3, 6, 8a–
e, 9a–e and 12a–e encourage us to propose a mechanism for the
reactions of 1,2-alkatrienephosphonates with sulphenyl- and selenenyl-
halogenides (Scheme 4).
The isolation of bromobenzene from the reaction mixtures of the syn-
thesis of compounds 2,3, 6, 8a–e, 9a–e and 12a–e supports the previ-
ously suggested reaction mechanism. We believe that the results re-
ported here are in accordance with the assumption 7−21 for the key role
of the formation of thiiranium or seleniranium ions A and C as inter-
mediates resolting from the 3,4 attack of the reagent. They undergo
ring expansion due to the anhimeric assistance of the neighboring dou-
ble bond, forming the more stable cyclic ions A1 and C1. Both A1 and
C1 undergo [1,5]-prototropic shift and elimination of bromobenzene to
give the phosphorylated thiophene and selenophene derivatives. The
formation of the products 11a–e and 13a–e is due to the 4,5 attack

1,2-Alkatrienephosphonates
1861
of the reagent. In these cases, both methyl groups stabilize the inter-
mediate B and facilitate its interaction with the internal nucleophilic
phosphoryl group, leading to the formation of the quasi-phosphonium
intermediate B1. The Arbuzov rearrangement of B1 (second step) leads
to the formation of 4-phenylthio(seleno)-5H-1,2-oxaphosphole-2-oxides
11a–e and 13a–e.
Having in mind the results reported here, our previous results and
literature data, we conclude that:
1. the synthetic potential of the phosphorylated alkatrienes makes
them very useful in organic synthesis;
2. by the reactions of these compounds with a number of electrophilic
reagents, different kinds of heterocyclic compounds were prepared
with good yields;
3. there is a possibility to control the structure of the products by vari-
ation of the type of the electrophile and of the substrate; and
4. as far as starting 1-alkynoles are easily available from the corre-
sponding carbonyl compounds and alkynes, the reactions discussed
here have to be taken into consideration as useful synthetic protocol
for the transformation of carbonyl compounds into the correspond-
ing cyclic products, bearing a phosphonate group.
EXPERIMENTAL
Analytical Methods
The 1H NMR spectra were measured at normal probe temperature on
a Jeol JNM-PS-10 spectrometer at 100 MHz using TMS as internal
reference in CDCl3 solution. Chemical shifts are given in ppm and are
positive downfield from the internal standard. The IR spectra were run
on an IR-72 spectrophotometer (Carl Zeiss Jena). Elemental analyses
were carried out by the University of Shumen Microanalytical Service
Laboratory. The solvents were purified by standard methods. All reac-
tions were carried out in oven-dried glassware under an argon atmo-
sphere and exclusion of moisture. All compounds were checked for their
purity on TLC plates.
Starting Materials
The dichlorides 1,4 and the dialkyl esters 7a–e and 10a–e were pre-
pared according to the procedure described.22 Phenylselenenylbromide
is commercially available. Phenylsulfenylbromide was synthesized ac-
cording to the procedure described.22

1862
D. D. Enchev and S. P. Stankolov
Synthesis of Compounds 2, 3, 5, 6: General Procedure
To a solution of 5 mmol of the appropriate dichloride (1 or 4) in methy-
lene chloride a solution of 5 mmol phenylsulfenyl- or phenylselenenyl-
bromide was added at low temperature (−12–10◦C). The solvent was
then removed in vacuo and the residue was purified by chromatography
(50 g silicagel, hexane/ethyl acetate 1:1).
(3-Methylthiophen-2-yl)methylphosphonic dichloride 2. C6H7Cl2-
OPS; Calcd.: P 13.52, Cl 30.65, S 14.03 %; Found: P 13.43, Cl 30.62,
1
3
S 14.00%; IR: ν(cm−1) 1262(P O); H NMR (CDCl3): δ 7.08 (dd, J
=
HH
5.0 Hz, 5 J = 0.8 Hz, 1H, thiophene-H); 6.99 (dd, 3 J = 5.0 Hz, 5 J
=
PH
HH
PH
1.0 Hz, 1H, thiophene-H); 3.69 (d, 2 J = 15.0 Hz, 2H, CH2-P); 2.15 (d
PH
5 J = 3.4 Hz, 3H, Me-C); 31P NMR (CDCl3): δ 15.5. Oil; yield 53%, b.p.
PH
141–143◦C (1.0 Torr).
(3-Methylselenophen-2-yl)methylphosphonic dichloride 3. C6H7-
Cl2OPSe; Calcd.: P 11.22, Cl 25.69 %; Found: P 11.13, Cl 25.62%; IR:
ν(cm−1) 1270(P O); 1H NMR (CDCl3): δ 7.76 (dd,3 J = 5.2 Hz, 5 J
=
HH
PH
0.8 Hz, 1H, selenophene-H); 6.99 (dd, 3 J = 5.2 Hz, 5 J = 1.2 Hz, 1H,
HH
PH
selenophene-H); 4.06 (d, 2 J = 16.3 Hz, 2H, CH2-P); 2.16 (d, 5 J = 3,5
PH
PH
Hz, 3H, Me-C); 31P NMR (CDCl3): δ 17.2. Oil, yield 58%, b.p. 145–146◦C
(1.0 Torr).
1-Bromo-5-methyl-4-(phenylthio)hexa-2,4-dien-3-ylphosphonic di-
chloride 5. C13H14Cl2BrOPS; Calcd.: P 7.74, Cl 17.72, Br 19.97, S
8.01%; Found: P 7.70, Cl 17.69, Br 19.94, S 7.98%; IR: ν(cm−1) 1262(P
,
O)
1
5
1595, 1620(C
C); H NMR (CDCl3): δ 1.74 (d, J = 5.3 Hz, 3H,
C
C
PH
CH3); 2.04 (d, 5 J = 7.0 Hz, 3H, CH3); 4.00 (dd, 4 J = 2.6 Hz, 3 J
=
PH
PH
HH
7.2 Hz, 2H, CH2 C); 6.91 (dt, 3 J = 25.6 Hz, 1H); 7.21 - 7.60 (m, 5H,
PH
Ph); 31P NMR (CDCl3): 17.5. Oil, yield 51%, b.p. 144–146◦C (1.0 Torr).
2-Isopropylselenophen-3-ylphosphonic dichloride 6. C7H9Cl2-
OPSe; Calcd.: P 10.68, Cl 24.45%; Found: P 10.59, Cl 24.42%; IR:
ν(cm−1) 1285(P O); 1H NMR (CDCl3): δ 7.60 (dd, 3 J = 4.8 Hz, 3 J
=
HH
PH
2.8 Hz, 1H, selenophene-H); 7.27 (dd, 4 J = 3.8 Hz, 3 JHH= 4.8 Hz,
PH
1H, selenophene-H); 3.92 (septett, 3 J = 5.8 Hz, 1H, CHMe2); 1.27
HH
(d, 3 J = 5.8 Hz, 6H, Me); 31P NMR (CDCl3): δ 16.9. Oil, yield 52%,
HH
b.p. 145–147◦C (1.0 Torr).
Synthesis of Compounds 8a–e and 9a–e: General Procedure
To a solution of 5 mmol of the appropriate dialkyl ester 7a–
e in methylene chloride a solution of 5 mmol of phenylsulphenyl-
or phenylselenenylbromide in methylene chloride was added at low
temperature (−12–10◦C). The solvent was then removed in vacuo

1,2-Alkatrienephosphonates
1863
and the residue was purified by chromatography (50 g silicagel, hex-
ane/ethyl acetate 1:1).
Dimethyl (3-Methylthiophen-2-yl)methylphosphonate 8a. C8H13-
O3PS, Calcd.: P 14.06, S 14.56%; Found: P 14.00, S 14.32%; IR: ν(cm−1
)
1
1279(P O), 1000(P
PH
C); H NMR (CDCl3): δ 7.06 (dd, 3 J = 5.0 Hz,
O
HH
5 J = 0.8 Hz, 1H, thiophene-H); 6.99 (dd, 3 J = 5.0 Hz, 5 J = 1.0
HH
PH
Hz, 1H, thiophene-H); 3.67 (d, 2 J = 15.1Hz, 2H, CH2 P); 2.16 (d,
PH
5 J = 3.4 Hz, 3H, Me-C); 3.76 (d, 3 J = 11.2 Hz, 6H, OMe); 31P NMR
PH
PH
(CDCl3): δ 16.7. Oil, yield 53%, b.p. 141–143◦C (1.0 Torr).
Diethyl (3-Methylthiophen-2-yl)methylphosphonate 8b. C10H17-
O3PS, Calcd.: P 12.47, S 12.91%; Found: P 12.35, S 12.88%; IR: ν(cm−1
)
1
1279(P O), 1000(P
PH
C); H NMR (CDCl3): δ 7.07 (dd, 3 J = 5.0 Hz,
O
HH
5 J = 0.9 Hz, 1H, thiophene-H); 6.99 (dd, 3 J = 5.0 Hz, 5 J
=
HH
PH
1.0 Hz, 1H, thiophene-H); 3.68 (d, 2 J = 15.0 Hz, 2H, CH2 P); 2.16
PH
(d, 5 J = 3.4 Hz, 3H, Me-C); 1.28 (m, 6H, OCH2CH3); 4.04 (m, 4H,
PH
OCH2CH3); 31P NMR (CDCl3): δ 17.7. Oil, yield 53%, b.p. 141–143◦C
(1.0 Torr).
Dipropyl (3-Methylthiophen-2-yl)methylphosphonate 8c. C12H21-
O3PS, Calcd.: P 11.20, S 11.60%; Found: P 11.15, S 11.55%; IR: ν(cm−1
)
1
1279(P O), 1000(P
PH
C); H NMR (CDCl3): δ 7.06 (dd, 3 J = 5.0 Hz,
O
HH
5 J = 0.8 Hz, 1H, thiophene-H); 6.98 (dd, 3 J = 5.0 Hz, 5 J = 1.0
HH
PH
Hz, 1H, thiophene-H); 3.67 (d, 2 J = 15.1 Hz, 2H, CH2 P); 2.14 (d,
PH
5 J = 3.4 Hz, 3H, Me-C); 0.85 (t, 6H, OCH2CH2CH3); 1.58 (m, 4H,
PH
OCH2CH2CH3); 3.96 (m, 4H, OCH2CH2CH3); 31P NMR (CDCl3): δ 16.2.
Oil, yield 53%, b.p. 141–143◦C (1.0 Torr).
Diisopropyl (3-Methylthiophen-2-yl)methylphosphonate 8d. C12-
H21O3PS, Calcd.: P 11.20, S 11.60%; Found: P 11.17, S 11.56%; IR:
1
ν(cm−1) 1279(P O), 1000(P
C); H NMR (CDCl3): δ 7.06 (dd, 3 J
=
O
HH
5.0 Hz, 5 J = 0.7 Hz, 1H, thiophene-H); 6.89 (dd, 3 J = 5.0 Hz, 5 J
=
PH
HH
PH
1.0 Hz, 1H, thiophene-H); 3.67 (d, 2 J = 15.1 Hz, 2H, CH2 P); 2.16
PH
5
(d, J = 3.4 Hz, 3H, Me-C); 1.26 (d, 12H, OCH(CH3)2); 4.26 (m, 2H,
PH
OCH(CH3)2); 31P NMR (CDCl3): δ 15.6. Oil, yield 53%, b.p. 141–143◦C
(1.0 Torr).
Di-sec-butyl (3-Methylthiophen-2-yl)methylphosphonate (8e). C14-
H25O3PS, Calcd.: P 10.17, S 10.53%; Found: P 10.12, S 10.48%; IR:
1
ν(cm−1) 1279(P O), 1000(P
C); H NMR (CDCl3): δ 7.06 (dd, 3 J
=
O
HH
5.0 Hz, 5 J = 0.8 Hz, 1H, thiophene-H); 6.99 (dd, 3 J = 5.0 Hz, 5 J
=
PH
HH
PH
1.0 Hz, 1H, thiophene-H); 3.67 (d, 2 J = 15.1 Hz, 2H, CH2 P); 2.16
PH
(d, 5 J = 3.4 Hz, 3H, Me-C); 0.88 (t, 6H, OCH(Me)CH2Me); 1.26 (d,
PH
6H, OCH(Me)CH2Me); 1.76 (m, 4H, OCH(Me)CH2Me); 4.26 (m, 2H,

1864
D. D. Enchev and S. P. Stankolov
OCH(Me)CH2Me); 31P NMR (CDCl3): δ 16.7. Oil, yield 53%, b.p. 141–
143◦C (1.0 Torr).
Dimethyl (3-Methylselenophen-2-yl)methylphosphonate (9a). C8-
H13O3PSe, Calcd.: P 11.59%; Found: P 11.55%; IR: ν(cm−1) 1285(P
,
O)
1
1016(P
C); H NMR (CDCl3): δ 7.06 (dd, 3 J = 5.0 Hz, 5 J = 0.9
O
HH
PH
Hz, 1H, selenophene-H); 6.89 (dd, 3 J = 5.0 Hz, 5 J = 1.0 Hz, 1H,
HH
PH
2
5
selenophene-H); 3.67 (d, J = 15.1 Hz, 2H, CH2 P); 2.16 (d, J
=
PH
PH
3.4 Hz, 3H, Me-C); 3.76 (d, 3 J = 11.2 Hz, 6H, OMe); 31P NMR (CDCl3):
PH
δ 16.6. Oil, yield 52%, b.p. 145–147◦C (1.0 Torr).
Diethyl (3-Methylselenophen-2-yl)methylphosphonate (9b). C10-
H17O3PSe, Calcd.: P 10.49%; Found: P 10.43%; IR: ν(cm−1) 1285(P
,
O)
1
1016(P
C); H NMR (CDCl3): δ 7.06 (dd, 3 J = 5.0 Hz, 5 J = 0.8
O
HH
PH
Hz, 1H, selenophene-H); 6.99 (dd, 3 J = 5.0 Hz, 5 J = 1.0 Hz, 1H,
HH
PH
2
5
selenophene-H); 3.67 (d, J = 15.1 Hz, 2H, CH2 P); 2.16 (d, J
=
PH
PH
3.4 Hz, 3H, Me-C); 1.28 (t, 6H, OCH2Me); 4.04 (m, 4H, OCH2Me); 31P
NMR (CDCl3): δ 16.7. Oil, yield 52%, b.p. 145–147◦C (1.0 Torr).
Dipropyl (3-Methylselenophen-2-yl)methylphosphonate (9c). C12-
H21O3PSe, Calcd.: P 9.58%; Found: P 9.51%; IR: ν(cm−1) 1285(P
,
O)
1
1016(P
C); H NMR (CDCl3): δ 7.06 (dd, 3 J = 5.0 Hz, 5 J = 0.8
O
HH
PH
Hz, 1H, selenophene-H); 6.99 (dd, 3 J = 5.0 Hz, 5 J = 1.0 Hz, 1H,
HH
PH
selenophene-H); 3.67 (d, 2 J = 15.1 Hz, 2H, CH2 P); 2.16 (d, 5 J = 3.4
PH
PH
Hz, 3H, Me-C); 0.85 (t, 6H, OCH2CH2Me); 1.58 (m, 4H, OCH2CH2Me);
3.96 (m, 4H, OCH2CH2Me); 31P NMR (CDCl3): δ 17.7. Oil, yield 52%,
b.p. 145–147◦C (1.0 Torr).
Diisopropyl (3-Methylselenophen-2-yl)methylphosphonate (9d).
C12H21O3PSe, Calcd.: P 9.58%; Found: P 9.53%; IR: ν(cm−1) 1285(P
,
O)
1
1016(P
C); H NMR (CDCl3): δ 7.06 (dd, 3 J = 5.0 Hz, 5 J = 0.8
O
HH
PH
Hz, 1H, selenophene-H); 6.99 (dd, 3 J = 5.0 Hz, 5 J = 1.0 Hz, 1H,
HH
PH
2
5
selenophene-H); 3.67 (d, J = 15.1 Hz, 2H, CH2 P); 2.16 (d, J
=
PH
PH
3.4 Hz, 3H, Me-C); 1.26 (d, 12H, OCHMe2); 4.26 (m, 2H, OCHMe2); 31
P
NMR (CDCl3): δ 16.5. Oil, yield 52%, b.p. 145–147◦C (1.0 Torr).
Di-sec-butyl (3-Methylselenophen-2-yl)methylphosphonate (9e).
C14H25O3PSe, Calcd.: P 8.82%; Found: P 8.80%; IR: ν(cm−1) 1285(P
,
O)
1016(P
;
1H NMR (CDCl3): δ 7.06 (dd, 3 J = 5.0 Hz, 5 J
=
O
C)
HH
PH
0.8 Hz, 1H, selenophene-H); 6.99 (dd, 3 J = 5.0 Hz, 5 J = 1.0 Hz,
HH
PH
1H, selenophene-H); 3.67 (d, 2 J = 15.1 Hz, 2H, CH2 P); 2.16 (d,
PH
5 J = 3.4 Hz, 3H, Me-C); 0.88 (t, 6H, OCH(Me)CH2Me); 1.26 (d,
PH
6H, OCH(Me)CH2Me); 1.76 (m, 4H, OCH(Me)CH2Me); 4.26 (m, 2H,
OCH(Me)CH2Me); 31P NMR (CDCl3): δ 14.7. Oil, yield 52%, b.p. 145–
147◦C (1.0 Torr).

1,2-Alkatrienephosphonates
1865
Synthesis of Compounds 11a–e and 12a–e: General Procedure
The syntheses of the compounds 11a–e and 12a–e were performed
by the procedure described.3
4-Phenylthio-5,5-dimethyl-3-ethenyl-2,5-dihydro-2-methoxy-1,2-
oxaphosphole-2-oxide (11a). C14H17O3PS, Calcd.: P 10.45, S 10.82%;
Found: P 10.40, S 10.79%; IR: ν(cm−1) 1268(P O), 1625(CH
,
CH2)
1585(C C), 1000(P
;
1H NMR (CDCl3): δ 5.37 (ddd, 3 JHH(cis) =
O
C)
10.6 Hz, 2 J = 1.3 Hz, 4 J = 2.0 Hz, 1H, CH CHH); 5.62 (ddd,
HH
PH
3 JHH(trans) = 16.5 Hz, J = 1.3 Hz, J = 1.0 Hz, 1H, CH CHH);
2
4
HH
PH
6.39 (ddd, 3 JHH(cis) = 10.6 Hz, 3 JHH(trans) = 16.7 Hz, 3 J = 27.8 Hz,
PH
1H, CH=CHH); 1.44 (s, 3H, Me), 1.49 (s, 3H, Me), 7.29-7.44 (m, 5H,
3
Ph); 3.76 (d, J = 11.2 Hz, 3H, OMe) 31P NMR (CDCl3): δ 24.4. Oil,
HH
yield 44%, b.p. 145–147◦C (1.0 Torr).
4-Phenylthio-5,5-dimethyl-3-ethenyl-2,5-dihydro-2-ethoxy-1,2-oxa-
phosphole-2-oxide (11b). C15H19O3PS, Calcd.: P 9.98, S 10.33%;
Found: P 9.93, S 10.29%; IR: ν(cm−1) 1268(P O), 1625(CH
,
CH2)
1585(C C), 1000(P
;
1H NMR (CDCl3): δ 5.37 (ddd, 3 JHH(cis) =
O
C)
10.6 Hz, 2 J = 1.3 Hz, 4 J = 2.0 Hz, 1H, CH CHH); 5.62 (ddd,
HH
PH
3 JHH(trans) = 16.5 Hz, J = 1.3 Hz, J = 1.0 Hz, 1H, CH CHH);
2
4
HH
PH
6.39 (ddd, 3 JHH(cis) = 10.6 Hz, 3 JHH(trans) = 16.7 Hz, 3 J = 27.8 Hz,
PH
1H, CH=CHH); 1.44 (s, 3H, Me), 1.49 (s, 3H, Me), 7.29-7.44 (m, 5H,
Ph); 1.28 (t, 3H, OCH2Me); 4.04 (m, 2H, OCH2Me); 31P NMR (CDCl3):
δ 24.2. Oil, yield 44%, b.p. 145–147◦C (1.0 Torr).
4-Phenylthio-5,5-dimethyl-3-ethenyl-2,5-dihydro-2-n-propoxy-1,2-
oxaphosphole-2-oxide (11c). C16H21O3PS, Calcd.: P 9.55, S 9.88%;
Found: P 9.49, S 9.81%; IR: ν(cm−1) 1268(P O), 1625(CH CH2), 1585(C
,
=
C)
1000(P
C); 1H NMR (CDCl3): δ 5.37 (ddd, 3 JHH(cis) = 10.6 Hz, 2 J
O
1.3 Hz, 4 J = 2.0 Hz, 1H, CH CHH); 5.62 (ddd, 3 JHH(trans) =H1H6.5
PH
Hz, 2 J = 1.3 Hz, 4 J = 1.0 Hz, 1H, CH CHH); 6.39 (ddd, 3 JHH(cis)
HH
PH
= 10.6 Hz, 3 JHH(trans) = 16.7 Hz, 3 J = 27.8 Hz, 1H, CH=CHH);
PH
1.44 (s, 3H, Me), 1.49 (s, 3H, Me), 7.29–7.44 (m, 5H, Ph); 0.85 (t, 3H,
OCH2CH2Me); 1.58 (m, 2H, OCH2CH2Me); 3.96 (m, 2H, OCH2CH2Me);
31P NMR (CDCl3): δ 24.8. Oil, yield 44%, b.p. 145–147◦C (1.0 Torr).
4-Phenylthio-5,5-dimethyl-3-ethenyl-2,5-dihydro-2-i-propoxy-1,2-
oxaphosphole-2-oxide (11d). C16H21O3PS, Calcd.: P 9.55, S 9.88%;
Found: P 9.53, S 9.82%; IR: ν(cm−1) 1268(P O), 1625(CH CH2), 1585(C
,
=
C)
1000(P
C); 1H NMR (CDCl3): δ 5.37 (ddd, 3 JHH(cis) = 10.6 Hz, 2 J
O
1.3 Hz, 4 J = 2.0 Hz, 1H, CH CHH); 5.62 (ddd, 3 JHH(trans) =H1H6.5
PH
Hz, 2 J = 1.3 Hz, 4 J = 1.0 Hz, 1H, CH CHH); 6.39 (ddd, 3 JHH(cis)
HH
PH
= 10.6 Hz, 3 JHH(trans) = 16.7 Hz, 3 J = 27.8 Hz, 1H, CH=CHH);
PH

1866
D. D. Enchev and S. P. Stankolov
1.44 (s, 3H, Me), 1.49 (s, 3H, Me), 7.29–7.44 (m, 5H, Ph); 1.26 (d, 6H,
OCHMe2); 4.62 (m, 1H, OCHMe2); 31P NMR (CDCl3): δ 24.8. Oil, yield
44%, b.p. 145–147◦C (1.0 Torr).
4-Phenylthio-5,5-dimethyl-3-ethenyl-2,5-dihydro-2-sec-butoxy-1,2-
oxaphosphole-2-oxide (11e). C17H23O3PS, Calcd.: P 9.15, S 9.47%;
Found P 9.10, S 9.41%; IR: ν(cm−1) 1268(P O), 1625(CH CH2), 1585(C
,
=
C)
1000(P
C); 1H NMR (CDCl3): δ 5.37 (ddd, 3 JHH(cis) = 10.6 Hz, 2 J
O
1.3 Hz, 4 J = 2.0 Hz, 1H, CH CHH); 5.62 (ddd, 3 JHH(trans) =H1H6.5
PH
Hz, 2 J = 1.3 Hz, 4 J = 1.0 Hz, 1H, CH CHH); 6.39 (ddd, 3 JHH(cis)
HH
PH
= 10.6 Hz, 3 JHH(trans) = 16.7 Hz, 3 J = 27.8 Hz, 1H, CH=CHH);
PH
1.44 (s, 3H, Me), 1.49 (s, 3H, Me), 7.29–7.44 (m, 5H, Ph), 0.88 (t,
3H, OCH(Me)CH2Me); 1.26 (d, 3H, OCH(Me)CH2Me); 1.76 (m, 2H,
OCH(Me)CH2Me); 4.62 (m, 1H, OCH(Me)CH2Me); 31P NMR (CDCl3):
δ 24.6. Oil, yield 44%, b.p. 145–147◦C (1.0 Torr).
Dimethyl 2-Isopropylthiophen-3-ylphosphonate (12a). C9H15O3PS,
Calcd.: P 13.22, S 13.69%; Found: P 13.12, S 13.63%; IR: ν(cm−1
)
1
1279(P O), 1010(P
PH
C); H NMR (CDCl3): δ 7.14 (dd, 3 J = 4.9 Hz,
O
HH
3 J = 4.0 Hz, 1H, thiophene-H); 7.30 (dd, 3 J = 5.0 Hz, 4 J = 3.0
HH
PH
3
Hz, 1H, thiophene-H); 3.94 (septett, J = 6.5 Hz, 1H, CHMe2); 1.44
HH
(d, 3 J = 6.5 Hz, 6H, CHMe2); 3.77 (d, 3 J = 11.2 Hz, 6H, OMe); 31
P
HH
PH
NMR (CDCl3): δ 14.7. Oil, yield 35%, b.p. 145–147◦C (1.0 Torr).
Diethyl 2-Isopropylthiophen-3-ylphosphonate (12b). C11H19O3PS,
Calcd.: P 11.80, S 12.22%; Found: P 11.78, S 12.18%; IR: ν(cm−1
)
1
1279(P O), 1010(P
PH
C); H NMR (CDCl3): δ 7.14 (dd, 3 J = 4.9 Hz,
O
HH
3 J = 4.0 Hz, 1H, thiophene-H); 7.30 (dd, 4 J = 3.0 Hz, 3 J = 5.0
PH
HH
3
Hz, 1H, thiophene-H); 3.94 (septett, J = 6.5 Hz, 1H, CHMe2); 1.44
HH
(d, 3 J = 6.5 Hz, 6H, CHMe2); 1.28 (t, 6H, OCH2Me); 4.04 (m, 4H,
HH
OCH2Me); 31P NMR (CDCl3): δ 11.9. Oil, yield 35%, b.p. 145–147◦C (1.0
Torr).
Dipropyl 2-isopropylthiophen-3-ylphosphonate (12c). C13H23O3-
PS, Calcd.: P 10.67, S 11.04%; Found: P 10.62, S 11.00%; IR: ν(cm−1
)
1
1279(P O), 1010(P
PH
C); H NMR (CDCl3): δ 7.14 (dd, 3 J = 4.9 Hz,
O
HH
3 J = 4.0 Hz, 1H, thiophene-H); 7.30 (dd, 3 J = 5.0 Hz, 4 J = 3.0
HH
PH
3
Hz, 1H, thiophene-H); 3.94 (septett, J = 6.5 Hz, 1H, CHMe2); 1.44
HH
(d, 3 J = 6.5 Hz, 6H, CHMe2); 0.85 (t, 6H, OCH2CH2Me); 1.58 (m, 4H,
HH
OCH2CH2Me); 3.96 (m, 4H, OCH2CH2Me); 31P NMR (CDCl3): δ 12.3.
Oil, yield 35%, b.p. 145–147◦C (1.0 Torr).
Diisopropyl 2-isopropylthiophen-3-ylphosphonate (12d). C13H23-
O3PS, Calcd.: P 10.67, S 11.04%; Found: P 10.64, S 11.00%; IR: ν(cm−1
)
1
1279(P O), 1010(P
C); H NMR (CDCl3): δ 7.14 (dd, 3 J = 4.9 Hz,
O
HH

1,2-Alkatrienephosphonates
1867
3 J = 4.0 Hz, 1H, thiophene-H); 7.30 (dd, 3 J = 5.0 Hz, 4 J = 3.0
PH
HH
PH
3
Hz, 1H, thiophene-H); 3.94 (septett, J = 6.5 Hz, 1H, CHMe2); 1.44
HH
3
(d, J = 6.5 Hz, 6H, CHMe2); 1.26 (d, 12H, OCHMe2); 4.26 (m, 4H,
HH
OCHMe2); 31P NMR (CDCl3): δ 9.7. Oil, yield 35%, b.p. 145–147◦C (1.0
Torr).
Di-sec-butyl
2-isopropylthiophen-3-ylphosphonate
(12e).
C9H15O3PS, Calcd.: P 9.73, S 10.07%; Found: P 9.70, S 10.00%;
IR: ν(cm−1) 1279(P O), 1010(P
:
1H NMR (CDCl3): δ 7.14 (dd,
O
C)
3 J = 4.9 Hz, 3 J = 4.0 Hz, 1H, thiophene-H); 7.30 (dd, 3 J
=
HH
PH
HH
5.0 Hz, 4 J = 3.0 Hz, 1H, thiophene-H); 3.94 (septett, 3 J = 6.5
PH
HH
Hz, 1H, CHMe2); 1.44 (d, 3 J = 6.5 Hz, 6H, CHMe2); 0.88 (t,
HH
6H, OCH(Me)CH2Me); 1.26 (d, 6H, OCH(Me)CH2Me); 1.76 (m, 4H,
OCH(Me)CH2Me); 4.26 (m, 2H, OCH(Me)CH2Me); 31P NMR (CDCl3):
δ 10.9. Oil, yield 35%, b.p. 145–147◦C (1.0 Torr).
Synthesis of the Compounds 13a-e: General Procedure
To a solution of 5 mmol of the appropriate dialkyl ester 10a–e in
methylene chloride a solution of 5 mmol of phenylselenenylbromide in
methylene chloride was added at low temperature (−12–−10◦C). The
solvent was then removed in vacuo and the residue was purified by
chromatography (50 g silicagel, hexane / ethyl acetate 1:1).
4-Phenylseleno-5,5-dimethyl-3-ethenyl-2,5-dihydro-2-methoxy-
1,2-oxaphosphole-2-oxide (13a). C14H17O3PSe, Calcd.:
P 9.02%;
Found: P 9.00%; IR: ν(cm−1) 1270(P O), 1630(CH CH2), 1580(C
,
C)
1010(P
C);1H NMR (CDCl3): δ 5.37 (ddd, 3 JHH(cis) = 10.6 Hz, 2 J
=
O
1.3 Hz, 4 J = 2.0 Hz, 1H, CH CHH); 5.62 (ddd, 3 JHH(trans) =H1H6.5
PH
Hz, 2 J = 1.3 Hz, 4 J = 1.0 Hz, 1H, CH CHH); 6.39 (ddd, 3 JHH(cis)
HH
PH
= 10.6 Hz, 3 JHH(trans) = 16.7 Hz, 3 J = 27.8 Hz, 1H, CH=CHH); 1.44
PH
(s, 3H, Me), 1.49 (s, 3H, Me), 7.29–7.44 (m, 5H, Ph); 3.76 (d, 3 J = 11.2
PH
Hz, 6H, OMe); 31P NMR (CDCl3): δ 31.7. Oil, yield 56%, b.p. 145–147◦C
(1.0 Torr).
4-Phenylseleno-5,5-dimethyl-3-ethenyl-2,5-dihydro-2-ethoxy-1,2-
oxaphosphole-2-oxide (13b). C15H19O3PSe, Calcd.: P 8.67%; Found:
P 8.61%; IR: ν(cm−1) 1270(P O), 1630(CH CH2), 1580(C C), 1010(P
;
O
C)
1H NMR (CDCl3): δ 5.37 (ddd, 3 JHH(cis) = 10.6 Hz, 2 J = 1.3 Hz,
HH
4 J = 2.0 Hz, 1H, CH CHH); 5.62 (ddd, 3 JHH(trans) = 16.5 Hz,
PH
2 J = 1.3 Hz, 4 J = 1.0 Hz, 1H, CH CHH); 6.39 (ddd, 3 JHH(cis)
PH
= H1H0.6 Hz, 3 JHH(trans) = 16.7 Hz, 3 J = 27.8 Hz, 1H, CH=CHH);
PH
1.44 (s, 3H, Me), 1.49 (s, 3H, Me), 7.29–7.44 (m, 5H, Ph); 1.28 (t, 3H,
OCH2Me); 4.04 (m, 2H, OCH2Me); 31P NMR (CDCl3): δ 29.0. Oil, yield
52%, b.p. 143–145◦C (1.0 Torr).

1868
D. D. Enchev and S. P. Stankolov
4-Phenylseleno-5,5-dimethyl-3-ethenyl-2,5-dihydro-2-n-propoxy-
1,2-oxaphosphole-2-oxide (13c). C16H21O3PSe, Calcd.: 8.34%;
P
Found: P 8.29%; IR: ν(cm−1) 1270(P O), 1630(CH CH2), 1580(C
,
C)
1010(P
;
1H NMR (CDCl3): δ 5.37 (ddd, 3 JHH(cis) = 10.6 Hz,
O
C)
2 J = 1.3 Hz, 4 J = 2.0 Hz, 1H, CH CHH); 5.62 (ddd, 3 JHH(trans)
PH
= H1H6.5 Hz, 2 J = 1.3 Hz, 4 J = 1.0 Hz, 1H, CH CHH); 6.39 (ddd,
HH
PH
3 JHH(cis) = 10.6 Hz, 3 JHH(trans) = 16.7 Hz, 3 J = 27.8 Hz, 1H,
PH
CH=CHH); 1.44 (s, 3H, Me), 1.49 (s, 3H, Me), 7.29–7.44 (m, 5H, Ph);
0.85 (t, 3H, OCH2CH2Me); 1.58 (m, 2H, OCH2CH2Me); 3.96 (m 2H,
OCH2CH2Me); 31P NMR (CDCl3): δ 30.0. Oil, yield 68%, b.p. 145–147◦C
(1.0 Torr).
4-Phenylseleno-5,5-dimethyl-3-ethenyl-2,5-dihydro-2-i-propoxy-
1,2-oxaphosphole-2-oxide (13d). C16H21O3PSe, Calcd.:
P 8.34%;
Found: P 8.28%; IR: ν(cm−1) 1270(P O), 1630(CH CH2), 1580(C
,
C)
3
1010(P
;
1H NMR (CDCl3): δ 5.37 (ddd, JHH(cis) = 10.6 Hz,
O
C)
2 J = 1.3 Hz, 4 J = 2.0 Hz, 1H, CH CHH); 5.62 (ddd, 3 JHH(trans)
= H1H6.5 Hz, 2 J = 1.3 Hz, 4 J = 1.0 Hz, 1H, CH CHH); 6.39 (ddd,
PH
HH
PH
3 JHH(cis) = 10.6 Hz, 3 JHH(trans) = 16.7 Hz, 3 J = 27.8 Hz, 1H,
PH
CH=CHH); 1.44 (s, 3H, Me), 1.49 (s, 3H, Me), 7.29–7.44 (m, 5H, Ph);
1.26 (d, 6H, OCHMe2); 4.62 (m, 1H, OCHMe2); 31P NMR (CDCl3): δ
29.0. Oil, yield 67%, b.p. 145–147◦C (1.0 Torr).
4-Phenylseleno-5,5-dimethyl-3-ethenyl-2,5-dihydro-2-sec-butoxy-
1,2-oxaphosphole-2-oxide (13e). C17H23O3PSe, Calcd.:
P 8.04%;
Found: P 8.00%; IR: ν(cm−1) 1270(P O), 1630(CH CH2), 1580(C
,
C)
1010(P
;
1H NMR (CDCl3): δ 5.37 (ddd, 3 JHH(cis) = 10.6 Hz,
O
C)
2 J = 1.3 Hz, 4 J = 2.0 Hz, 1H, CH CHH); 5.62 (ddd, JHH(trans)
3
= H1H6.5 Hz, 2 J = 1.3 Hz, 4 J = 1.0 Hz, 1H, CH CHH); 6.39 (ddd,
PH
HH
PH
3 JHH(cis) = 10.6 Hz, 3 JHH(trans) = 16.7 Hz, 3 J = 27.8 Hz, 1H,
PH
CH=CHH); 1.44 (s, 3H, Me), 1.49 (s, 3H, Me), 7.29–7.44 (m, 5H, Ph);
0.88 (t, 3H, OCH(Me)CH2Me); 1.26 (d, 3H, OCH(Me)CH2Me); 1.76
(m, 2H, OCH(Me)CH2Me); 4.62 (m, 1H, OCH(Me)CH2Me); 31P NMR
(CDCl3): δ 29.0. Oil, yield 56%, b.p. 175–177◦C (1.0 Torr).
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1,2-Alkatrienephosphonates
1869
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