Small organophosphorus-selenium heterocycles from the selenation of conjugated ketones and enals

Article abstract of DOI:10.1055/s-0031-1290349

Reaction of 2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide [Woollins' reagent, WR] with equimolar amount of ,-unsaturated ketones [R ¹C(O)C=CR² (R¹ = aryl or alkyl; R² = -aryl)] leads to a series of novel five-membered C₃P(Se)Se hetero-cycles 1-8 in 48-95% isolated yields. Furthermore, WR reacts with one equivalent of aromatic conjugated enals [RC=CC=O, R = Ph and 2-MeOC ₆H₄] to give five-membered C₃P(Se)Se heterocycles 9 and 10 via the cleavage/cyclic extension of WR molecular ring. All new compounds have been characterised spectroscopically (³¹P NMR, ⁷⁷Se NMR, ¹H NMR, ¹³C NMR, IR and mass spectroscopy) and one representative X-ray structure is reported. Georg Thieme Verlag Stuttgart · New York.

Full text of DOI:10.1055/s-0031-1290349

1170
LETTER
Small Organophosphorus–Selenium Heterocycles from the Selenation of
Conjugated Ketones and Enals
S
mall Organophos
u
phorus–Sele
o
niumHeteroc
x
ycles iong Hua, Alexandra M. Z. Slawin, J. Derek Woollins*
EastChem School of Chemistry, University of St Andrews, Fife, KY16 9ST, UK
Fax +44(1334)463384; E-mail: jdw3@st-and.ac.uk
Received 28 November 2011
a,b-unsaturated ketones according to Scheme 1. No obvi-
Abstract: Reaction of 2,4-bis(phenyl)-1,3-diselenadiphosphetane-
2,4-diselenide [Woollins’ reagent, WR] with equimolar amount of
a,b-unsaturated ketones [R1C(O)C=CR2 (R1 = aryl or alkyl; R2 =
aryl)] leads to a series of novel five-membered C3P(Se)Se hetero-
ous differences of yield were found when the reaction of
WR with two or more equivalents of a,b-unsaturated ke-
tones was carried out. That means the reaction straightfor-
cycles 1–8 in 48–95% isolated yields. Furthermore, WR reacts with wardly generates unique five-membered ring systems.
one equivalent of aromatic conjugated enals [RC=CC=O, R = Ph
and 2-MeOC6H4] to give five-membered C3P(Se)Se heterocycles 9
Cleavage of the four-membered P2Se2 ring in WR affords
1–8 in good to excellent yields as pastes or solids
and 10 via the cleavage/cyclic extension of WR molecular ring. All
(Table 1). All compounds are soluble in chlorinated sol-
new compounds have been characterised spectroscopically (31P
vents and stable in air for months without any signals of
degradation.
NMR, 77Se NMR, 1H NMR, 13C NMR, IR and mass spectroscopy)
and one representative X-ray structure is reported.
Key words: selenium, phosphorus, heterocycles, Woollins’ re-
agent, X-Ray structure
Se
Ph
Ph
Se
Se
Ph
Se
P
P
H
Se
O
R1
P
Se
R1
Se
WR
toluene, reflux, 7 h
Se
P
Ph
R2
R1
R2
+
R2
The synthesis of selenium-containing heterocyclic com-
pounds has gained considerable attention in recent years,
because of their interesting reactivities and potential phar-
maceutical properties,1,2 new materials3 as well as re-
agents and catalysts.4 However, synthesis of selenium-
containing organic heterocycles is not always easy due to
the inconvenience of typical selenium reagents such as
H2Se, NaHSe, (Me3Si)2Se, potassium selenocyanate and
tetraethylammonium tetraselenotungstate [Et4N]2WSe4,
each exhibiting its own problems including toxicity, solu-
bility, difficulty in handling and poor reactivity. 2,4-
Bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide
[PhP(Se)(m-Se)]2, known as Woollins’ reagent, WR, has
become an efficient selenation reagent in synthetic chem-
istry in recent years5 due to its less unpleasant chemical
properties and ready preparation in air.6 WR has been ap-
plied as a selenation agent for the synthesis of a wide se-
lenium-containing compounds ranging from simple
oxygen–selenium exchange to the formation of complex
phosphorus–selenium heterocycles5–14as well as the sur-
prising phosphorus–selenium-free products.15,16
H
A
B
Scheme 1 Synthesis of five-membered heterocycles 1–8 from the
selenation of a,b-unsaturated ketones
Table 1 Yields of Se-Alkyl-O-alkylphenylphosphono Diselenoates
1–8
Product
R1
R2
Yield (%)
1
2
3
4
5
6
7
8
Ph
Ph
92
95
81
84
83
67
50
48
Ph
4-MeOC6H4
Ph
Me
4-MeC6H4
PhCH=CH
thiophen-2-yl
Me2N
4-FC6H4
Ph
4-O2NC6H4
3-BrC6H4
thiophen-2-yl
thiophen-2-yl
In continuation of our studies designed to explore the re-
activity of WR towards a variety of organic substituents
as building blocks for heterocyclic compounds, herein, we
report the synthesis and characterisation of a series of
novel organophosphorus–selenium heterocycles from re-
action of WR with a,b-unsaturated ketones and enals.
The characterisation of 1–8 is based on their 1H NMR, 13C
NMR, 31P NMR and 77Se NMR, IR spectroscopy, mass
spectrometry and elemental microanalysis. All of com-
pounds showed the anticipated molecular ion peaks [M +
Na]+, [M + H]+ or [M]+, and satisfactory accurate mass
measurements or satisfactory elemental analysis. The
phosphorus atom and the tetrahedral carbon atom in com-
pounds 1–8 are potentially stereogenic centres. Thus,
compounds 1–8 are stereotopic with (R,R), (S,S), (S,R)
and (R,S) stereoisomers possible. In the 31P NMR spectra
of 1, 2, 4, 5 and 7 two phosphorus signals with different
intensity ratio (see experiment section) were observed at
The synthesis of five-membered heterocycles 1–8 was
performed via the reaction of WR with one equivalent of
SYNLETT 2012, 23, 1170–1174
x
x
.
x
x
.
2
0
1
1
Advanced online publication: 10.02.2012
DOI: 10.1055/s-0031-1290349; Art ID: B72411ST
© Georg Thieme Verlag Stuttgart · New York

LETTER
Small Organophosphorus–Selenium Heterocycles
1171
dP = 56.1–73.0 ppm, flanked by two sets of satellites for five-membered ring in compound 1A, build up a nearly
the endocyclic and exocyclic selenium atoms [J(P,Seindo planar conformation. Meanwhile, the deviation of the P(1)
)
coupling constants being in the range of 333–369 Hz and atom from the plane of Se(1)–C(1)–C(2)–C(3) is 0.644 Å.
J(P,Seexo) coupling constants in the range of 782–806 Hz] The dihedral angles between the Se(1)–C(1)–C(2)–C(3)
though we are not able to assign them specifically to and three phenyl rings [C(4)–C(9), C(10)–C(15) and
(R,R), (S,S), (S,R) and (R,S) stereoisomers. Meanwhile, in C(16)–C(21)] are 56.9°, 32.8° and 88.6°, respectively.
the 31P NMR spectra of compound 3, 6 and 8 four phos- The relative short P(1)–C(4) bond length of 1.830(5) Å,
phorus signals with different intensity ratios (see experi- compared to the P(1)–C(3) bond distance [1.862(5) Å],
ment section) were found at dP = 54.1–75.6 ppm, flanked indicates partial double bond character. The distances
by two sets of satellites for the endocyclic and exocyclic of P(1)–Se(1) and P(1)–Se(2) of 2.2540(13) Å and
selenium atoms [J(P,Seindo) coupling constants being in 2.0954(13) Å are similar to P–Se and P=Se bond lengths
the range of 331–390 Hz and J(P,Seexo) coupling constants previously observed for other related compounds contain-
in the range of 765–832 Hz], and suggesting the presence ing the P(Se)(m-Se) unit.19–21
of somewhat less steric effects, compared with com-
pounds 1, 2, 4, 5 and 7. The 77Se NMR spectra showed
two doublet signals in the ranges of d = 354.9–487.1 ppm
and d = –83.2 to –203.3 ppm for each stereoisomer
(Table 2). Attempts to further purify 1–8 by recrystallisa-
tion proved unsuccessful.
Table 2 31P NMR and 77Se NMR Data for Compounds 1–8
Product dP
(ppm)
dSe-endo
(ppm)
JSe–P
(Hz)
dSe-exo
(ppm)
JSe=P
(Hz)
1
2
3
72.4
71.4
408.9
391.5
346
346
–187.5
–170.8
806
786
73.0
71.6
406.7
390.0
336
345
–188.2
–174.1
801
784
75.6
75.3
74.7
61.7
443.9
421.4
405.5
449.7
390
336
346
390
–125.9
–182.8
–156.7
–111.7
765
801
782
770
Figure 1 X-ray structure of 1A (hydrogen atoms omitted for clari-
ty). Selected bond lengths (Å) and angles (°): C(1)–C(2): 1.325(6),
C(1)–C(10): 1.486(6), C(1)–Se(1): 1.954(4), Se(1)–P(1): 2.2540(13),
Se(2)–P(1): 2.0954(13), P(1)–C(4): 1.830(5), P(1)–C(3): 1.862(5),
C(2)–C(3): 1.515(6); C(2)–C(1)–C(10): 127.6(4)°, C(2)–C(1)–Se(1):
4
5
6
72.0
70.7
400.7
386.5
340
357
–191.1
–177.8
803
789
116.7(3)°,
88.32(13)°,
C(10)–C(1)–Se(1):
C(4)–P(1)–C(3):
115.7(3)°,
109.2(3)°,
C(1)–Se(1)–P(1):
C(4)–P(1)–Se(2):
70.3
69.9
370.4
354.9
338
350
–188.0
–170.0
803
782
112.67(15)°, C(3)–P(1)–Se(2): 115.81(15)°, C(4)–P(1)–Se(1):
107.08(15)°, C(3)–P(1)–Se(1): 95.82(14)°, Se(2)–P(1)–Se(1):
115.50(6)°, C(1)–C(2)–C(3): 122.8(4)°.
73.7
71.8
61.0
54.1
414.8
405.6
473.1
487.1
329
341
365
381
–190.8
–166.7
–161.5
–83.2
832
796
793
782
Similarly to Scheme 1, WR reacts with one equivalent of
aromatic a,b-unsaturated enals in refluxing toluene result-
ing in the corresponding five-membered phosphorus–se-
lenium heterocycles 9 and 10 in respective 79% and 56%
isolated yields (Scheme 2). The compounds were isolated
as stable and reddish yellow paste (9) or greyish yellow
solid (10). The molecular ion peaks [M + H]+ and satisfac-
tory accurate mass measurement results, together with
NMR data are consistent with the anticipated formulas.
Once again, both phosphorus atom and tetrahedral carbon
atom in the newly formed five-membered ring in com-
pounds 9 and 10 are potentially chiral centres with (R,R),
(S,S), (S,R) and (R,S) stereoisomers possible. In fact, two
stereoisomers were observed in 9, and four in 10 (see ex-
perimental section). The introduction of the bigger bulky
group (2-MeOC6H4) or the smaller bulky group (Ph) is re-
flected in the distribution of stereoisomers in the product.
7
8
57.0
56.1
450.0
455.2
333
369
–131.6
–131.2
787
785
71.1
69.1
61.0
60.5
407.3
412.7
477.2
398.5
336
341
377
393
–203.3
–176.7
–166.4
–142.5
810
792
789
777
The structural features of the new five-membered ring in
compound 1A are analogous to those observed for com-
pound 5A, whose X-ray structure has been reported previ-
ously by our group.17 The spectroscopic and analytical
data are in agreement with the structure of 1A determined
by X-ray crystallography (Figure 1)18 and its geometry is
best described as a distorted ‘open envelope’ conforma-
tion, with one phenyl ring in the equatorial position and
two other phenyl rings in axial plane. The atoms Se(1),
C(1), C(2) and C(3) which constitute the newly formed
Mechanistically, we propose a possible pathway for the
formation of heterocycles 1–10 as shown in Scheme 3.
© Thieme Stuttgart · New York
Synlett 2012, 23, 1170–1174

1172
G. Hua et al.
LETTER
Similar to its sulfur analogue, Lawesson’s reagent22 WR isomers. Meanwhile, in the cases of products 3, 6, 8 and 9
can also undergo four-membered P2Se2 ring-opening two isomers A and B co-exist to give four stereoisomers.
mechanism with a propensity leading to several types of Unfortunately, we are not able to further separate or iden-
fragments which were confirmed by mass spectrometry.23 tify the different isomers.
At elevated temperature PhPSe2 (I) is known as the reac-
tive species in solution. The first step in the formation of
1–10 is a [2+2]-cycloaddition of a P=Se bond from
In conclusion, Woollins’ reagent reacts with equimolar
amount of a,b-unsaturated ketones in refluxing toluene
giving a series of novel five-membered C3P(Se)Se hetero-
PhPSe2 (I) across the C=O bond of ketones or enals giving
rise to an intermediate II, in which the four-membered P–
Se–C–O ring breaks to generate an unstable a,b-unsatur-
ated selenoketone or selenoenal III by loss of a molecule
of PhP(Se)(O). Then, a further [2+2]-cycloaddition of a
P=Se bond from PhPSe2 (I) with the C=Se bond of inter-
mediate III results in an intermediate IVa, existing in
equilibrium in solution with IVb. The latter can readily be
rearranged to intermediate V, followed by intramolecular
cyclisation to afford the six-membered ring VIa, which is
likely in equilibrium with its iso-structural VIb in solution
at elevated temperature. Finally, we propose that both VIa
and VIb can be undergo ring contraction by elimination of
a molecule of selenium to give the more stable five-mem-
bered heterocycles 1–10. Therefore, the form A is formed
in products 1, 2, 4, 5, 7 and 10 consisting of two stereo-
cycles in good to excellent isolated yields.24 Meanwhile,
treating WR with an equivalent of aromatic conjugated
enals under identical conditions resulted in the similar
five-membered C3P(Se)Se heterocycles.24 Two or four
stereoisomers were observed by 31P NMR and 77Se NMR
spectra.
Acknowledgment
The authors are grateful to the University of St Andrews for finan-
cial support.
References and Notes
(1) Wirth, T. Organoselenium Chemistry: Modern Development
in Organic Synthesis; Springer: Berlin, 2000.
(2) (a) Srivastava, P. C.; Robin, R. K. J. Med. Chem. 1983, 26,
445. (b) Kumar, Y.; Green, R.; Borysko, K. Z.; Wise, D. S.;
Wotring, L.; Townsend, L. B. J. Med. Chem. 1993, 36,
3843. (c) Koketsu, M.; Hishihara, H.; Wu, W.; Murakami,
K.; Saiki, I. Eur. J. Pharm. Sci. 1999, 9, 156. (d) Wu, W.;
Murakami, K.; Koketsu, M.; Yamada, Y.; Saiki, I.
Anticancer Res. 1999, 19, 5375.
Ph
Se
Se
Ph
Se
P
P
Ph
Se
Se
H
Se
WR
O
Se
P
Se
R
R
P
+
R
H
Ph
toluene, reflux, 7 h
A
B
H
(3) (a) Garin, J. Adv. Heterocycl. Chem. 1995, 62, 249.
(b) Uemoto, T. Adv. Heterocycl. Chem. 1995, 64, 323.
(4) (a) Back, T. G. Organoselenium Chemistry, A Practical
Approach; Oxford University Press: Oxford, 1999.
(b) Mlochowski, J. Phosphorus, Sulfur Silicon 1998, 191,
136. (c) Tiecco, M. Top. Curr. Chem. 2000, 208, 7.
(d) Wirth, T. Angew. Chem. Int. Ed. 2000, 208, 3742.
(e) Mlochowski, J.; Brzaszcz, M.; Giurg, M.; Palus, J.;
Wojtowicz, H. Eur. J. Org. Chem. 2003, 4329.
(5) Hua, G.; Woollins, J. D. Angew. Chem. Int. Ed. 2009, 48,
1368.
9 R = Ph
10 R = 2-MeOC6H4
Scheme 2 Synthesis of five-membered heterocycles 9 and 10 from
Ph
Se P Se
Se
Se
Se
R1CH=CHC(O)R2
[2+2]
Ph
Se
Se
Ph
P
P
P
Ph
R1
C C
H H
C
R2
II
O
Se
WR
I
(6) Gray, I. P.; Bhattacharyya, P.; Slawin, A. M. Z.; Woollins,
J. D. Chem. Eur. J. 2005, 11, 6221.
(7) Hua, G.; Henry, J. B.; Li, Y.; Mount, A. R.; Slawin, A. M.
Z.; Woollins, J. D. Org. Biomol. Chem. 2010, 8, 1655.
(8) Hua, G.; Li, Y.; Fuller, A. L.; Slawin, A. M. Z.; Woollins,
J. D. Eur. J. Org. Chem. 2009, 1612.
PhP(O)(Se)
Se
Ph
Se P Se
Ph
PhPSe2
[2+2]
Se
Se P
C
R2
C
Se
C
R2
IVa
Se
R1
R1
R1
R2
IVb
III
(9) Hua, G.; Fuller, A. L.; Li, Y.; Slawin, A. M. Z.; Woollins,
J. D. New J. Chem. 2010, 34, 1565.
(10) Hua, G.; Fuller, A. L.; Slawin, A. M. Z.; Woollins, J. D. Eur.
J. Org. Chem. 2010, 2707.
Ph
Se
Ph
Se
R1
R1
Ph
P
Se
C
Se
P
P
Se
C
R2
Se
H
R1
C
H
Se
Se
Se
C
(11) Hua, G.; Fuller, A. L.; Slawin, A. M. Z.; Woollins, J. D.
R2
VIa
R2
VIb
Polyhedron 2011, 30, 805.
(12) Hua, G.; Fuller, A. L.; Slawin, A. M. Z.; Woollins, J. D. Eur.
J. Org. Chem. 2011, 3067.
(13) Hua, G.; Griffin, J. M.; Ashbrook, S. E.; Slawin, A. M. Z.;
Woollins, J. D. Angew. Chem. Int. Ed. 2011, 50, 4123.
(14) Hua, G.; Cordes, D. B.; Li, Y.; Slawin, A. M. Z.; Woollins,
J. D. Tetrahedron Lett. 2011, 52, 3311.
(15) Hua, G.; Woollins, J. D. Tetrahedron Lett. 2007, 48, 3677.
(16) Hua, G.; Li, Y.; Slawin, A. M. Z.; Woollins, J. D. Dalton
Trans. 2007, 1477.
V
Se
Se
Se
Ph
Se
Se
R1
R1
P
P
+
Se
R2
Ph
R2
A
B
1–8
9,10 R1 = aryl, R2 = H
R1 = alkyl or aryl, R2 = aryl
(17) Hua, G.; Li, Y.; Slawin, A. M. Z.; Woollins, J. D. Acta
Crystallogr., Sect. E 2008, E64, o184.
Scheme 3 Possible mechanism for the formation of five-membered
heterocycles 1–10
Synlett 2012, 23, 1170–1174
© Thieme Stuttgart · New York

LETTER
Small Organophosphorus–Selenium Heterocycles
1173
(18) Crystallographic Data for Compound 1a: C21H17PSe2, M =
458.24, monoclinic, space group P21/n, a = 9.948 (3), b =
16.347 (7), c = 11.640 (4) Å, b = 102.399 (8)°, U = 1848.7
(11) Å3, Z = 4, m = 1.646 mm–1, 12616 reflections, 3627
unique (Rint = 0.038); R1 = 0.044, wR2 = 0.106.
(19) Bhattacharyya, P.; Slawin, A. M. Z.; Woollins, J. D.
J. Organomet. Chem. 2001, 623, 116.
(20) (a) Bhattacharyya, P.; Slawin, A. M. Z.; Woollins, J. D.
Chem. Eur. J. 2002, 8, 2705. (b) Bhattacharyya, P.; Slawin,
A. M. Z.; Woollins, J. D. Dalton Trans. 2001, 300.
(c) Bhattacharyya, P.; Novosad, J.; Phillips, J. R.; Slawin, A.
M. Z.; Williams, D. J.; Woollins, D. J. Dalton Trans. 1995,
1607.
(21) Shore, J. T.; Pennington, W. T.; Noble, M. C.; Cordes, A. W.
Phosphorus, Sulfur Silicon Relat. Elem. 1988, 39, 153.
(22) Weng, Z.; Leong, W. K.; Vittal, J. J.; Goh, L. Y.
Organometallics 2003, 22, 1465.
(23) Pilkington, M. J.; Slawin, A. M. Z.; Williams, D. J.; Wood,
P. T.; Woollins, J. D. Heteroatom. Chem. 1990, 1, 351.
(24) Experimental Section: Unless otherwise stated, all reactions
were carried out under an oxygen-free nitrogen atmosphere
using pre-dried solvents and standard Schlenk techniques,
subsequent chromatographic and workup procedures were
performed in air. 1H NMR (270 MHz), 13C NMR (67.9
MHz), 31P-{1H} NMR (109 MHz) and 77Se-{1H} (51.4 MHz
referenced to external Me2Se) NMR spectra were recorded
at 25 °C (unless stated otherwise) on a JEOL GSX 270
spectrometer. IR spectra were recorded as KBr pellets in the
range of 4000–250 cm–1 on a Perkin–Elmer 2000 FTIR/
Raman spectrometer. Microanalysis was performed by the
University of St-Andrews microanalysis service. Mass
spectrometry was performed by the EPSRC National Mass
Spectrometry Service Centre, Swansea and the University of
St Andrews Mass Spectrometry Service. X-ray crystal data
for 1, were collected using a Rigaku SCXMIni Mercury
CCD system. Intensity data were collected using w steps
accumulating area detector images spanning at least a
hemisphere of reciprocal space. The data were corrected
for Lorentz polarisation effects. Absorption effects were
corrected on the basis of multiple equivalent reflections or
by semi-empirical methods. Structures were solved by direct
methods and refined by full-matrix least-squares against F2
by using the program SHELXTL.25 Hydrogen atoms were
assigned riding isotropic displacement parameters and
constrained to idealised geometries. The data (CCDC
855701) can be obtained free of charge via
JH,H = 3.6 Hz, JP,H = 18.2 Hz, 1 H, HC), 5.09 (dd, JH,H = 3.6
Hz, JP,H = 18.2 Hz, 1 H, HC). 13C NMR (CD2Cl2): d = 142.3,
142.0, 141.8, 141.7, 136.1, 134.6, 134.1, 134.0, 133.1,
132.9, 132.8, 132.4, 132.1, 131.8, 131.7, 129.4, 129.0,
129.0, 128.8, 128.6, 128.5, 128.3, 128.2, 128.0, 127.9,
127.8, 127.3, 127.2, 125.4, 124.9, 71.6 (d, JP,C = 30.1 Hz),
65.8 (d, JP,C = 29.1 Hz). 31P NMR (CD2Cl2): d = 72.4 (s,
JP–Se = 346 Hz, JP=Se = 806 Hz), 71.4 (s, JP–Se = 346 Hz,
JP=Se = 786 Hz). 77Se NMR (CD2Cl2): d = 408.9 (d, JP–Se
=
346 Hz), 391.5 (d, JP–Se = 346 Hz), –170.8 (d, JP=Se = 786
Hz), –187.5 (d, JP=Se = 806 Hz). MS (ESI+): m/z = 483 [M +
Na]+. MS (CI+): m/z = 461 [M + H]+. HRMS (CI+): m/z [M +
H]+ calcd for C21H18PSe2: 460.9471; found: 460.9473.
Compound 2: yellowish milky solid (466 mg) in 95%
isolated yield. IR (KBr): 1607 (m, C=C), 1510 (s, C=C),
1435 (m), 1303 (m), 1251 (s), 1177 (m), 1090 (m), 1030 (m),
831 (m), 746 (m), 688 (m), 596 (m), 521 (m) cm–1. A pair of
stereoisomers was found in ca. 4:6 intensity ratio. 1H NMR
(CD2Cl2): d = 8.22 (dd, JH,H = 6.9 Hz, 2 × 4 H, ArH), 6.92–
7.75 (m, 2 × 10 H, ArH), 6.65 (dd, 2 × 1 H, HC=C), 5.45 (dd,
JP,H = 17.6 Hz, 2 × 1H, HC), 3.80 (s, 3 H, OMe), 3.69 (s, 3
H, OMe). 13C NMR (CD2Cl2): d = 141.8, 141.7, 141.4,
141.3, 136.2, 133.2, 133.0, 132.4 (d, JP,C = 3.1 Hz), 132.2 (d,
JP,C = 3.1 Hz), 131.9, 131.7, 130.6, 130.5, 129.5, 129.4,
129.1, 129.0, 128.9, 128.7, 128.1, 127.9, 127.4, 127.3,
125.8, 125.3, 71.0 (d, JP,C = 31.1 Hz), 65.2 (d, JP,C = 29.1
Hz), 55.3. 31P NMR (CD2Cl2): d = 73.0 (s, JP–Se = 336 Hz,
JP=Se = 801 Hz), 71.6 (s, JP–Se = 345 Hz, JP=Se = 784 Hz). 77Se
NMR (CD2Cl2): d = 406.7 (d, JP–Se = 336 Hz), 390.0 (d, JP–Se
= 345 Hz), –174.1 (d, JP=Se = 784 Hz), –188.2 (d, JP=Se = 801
Hz). MS (CI+): m/z = 491 [M + H]+. HRMS (CI+): m/z [M +
H]+ calcd for C22H20OPSe2: 490.9577; found: 490.9582.
Compound 3: pale yellow paste (320 mg) in 81% isolated
yield. IR (KBr): 1555 (w, C=C), 1489 (m), 1433 (m), 1090
(m), 764 (m), 745 (m), 689 (s), 558 (m), 526 (m), 505 (m)
cm-1. Four stereoisomers were found in ca. 4:4:2:2 intensity
ratio. 1H NMR (CD2Cl2): d = 7.98–8.19 (m, 4 × 2 H, ArH),
6.91–7.64 (m, 4 × 8 H, ArH), 6.38–6.63 (m, 4 × 1 H, CH),
5.92–6.19 (m, 4 × 1 H, CH), 2.32–2.34 (s, 4 × 3 H, Me).
13C NMR (CD2Cl2): d = 141.3, 141.1, 140.0, 139.9, 138.3,
138.2, 134.5, 134.4, 133.1, 132.9, 132.4, 132.3, 132.0,
131.7, 131.5, 129.4, 129.3, 129.1, 128.8, 128.7, 128.6,
128.4, 128.2, 128.1, 128.0, 127.9, 127.7, 125.3, 71.2, 70.8,
65.3, 64.9, 21.9, 21.2. 31P NMR (CD2Cl2): d = 75.6 (s,
JP–Se = 390 Hz, JP=Se = 765 Hz), 75.3 (s, JP–Se = 336 Hz, JP=Se
= 801 Hz), 74.7 (s, JP–Se = 346 Hz, JP=Se = 782 Hz), 61.7 (s,
JP–Se = 390 Hz, JP=Se = 770 Hz). 77Se NMR (CD2Cl2): d =
449.7 (d, JP–Se = 390 Hz), 443.9 (d, JP–Se = 390 Hz), 421.4 (d,
www.ccdc.cam.ac.uk/conts/retrieving.html or from the
Cambridge Crystallographic Data centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax +44(1223)336033; e-mail:
deposit@ccdc.cam.ac.uk.
JP–Se = 336 Hz), 405.5 (d, JP–Se = 346 Hz), –111.7 (d, JP=Se
=
770 Hz), –125.9 (d, JP=Se = 765 Hz), –156.7 (d, JP=Se = 782
Hz), –182.8 (d, JP=Se = 801 Hz). MS (EI+): m/z = 398 [M]+.
HRMS (EI+): m/z [M]+ calcd for C16H15P76Se2: 389.9290;
found: 389.99293.
General Procedure for Synthesis of Compounds 1–8
from the Selenation of a,b-Unsaturated Ketones: A
mixture of a,b-unsaturated ketone (1.0 mmol) and WR (0.54
g, 1.0 mmol) in anhyd toluene (20 mL) was refluxed for 7 h.
Red suspension disappeared and a pale brown solution was
formed along with small amount of grey elemental selenium
precipitate. Upon cooling to r.t. and removing the unreacted
solid by filtration the filtrate was dried in evaporator and
purified by silica gel column (eluent: EtOAc–CH2Cl2, 1:1) to
give compounds 1–8.
Compound 4: orange solid (414 mg) in 84% isolated yield.
IR (KBr): 1601 (m, C=C), 1505 (vs, C=C), 1434 (s), 1224
(s), 1158 (m), 1090 (m), 834 (s), 745 (s), 687 (m), 526 (m),
508 (s) cm–1. A pair of stereoisomers was found in ca. 1:2
intensity ratio. 1H NMR (CD2Cl2): d = 8.14–8. 22 (d, JH,H
=
7.2 Hz, 2 × 2 H, ArH), 6.74–7.69 (m, 2 × 11 H, ArH), 6.40–
6.52 (d, 2 × 1 H, CH), 5.44–5.50 (d, 2 × 1 H, CH), 2.38 (s, 3
H, Me), 2.37 (s, 3 H, Me). 13C NMR (CD2Cl2): d = 164.6,
164.3, 161.0, 160.8, 140.0, 133.1, 132.9, 132.5, 132.3,
131.8, 131.6, 131.0, 130.3, 129.9, 129.7, 129.1, 128.8,
128.6, 128.5, 128.1, 127.9, 127.6, 127.2, 127.1, 124.1,
123.8, 70.9, 70.5, 65.1, 64.6, 21.1, 21.0. 31P NMR (CD2Cl2):
Compound 1: yellow paste (425 mg) in 92% isolated yield.
IR (KBr): 1599 (m, C=C), 1490 (m), 1434 (m), 1088 (m),
749 (s), 690 (s), 595 (m), 513 (m) cm–1. A pair of
stereoisomers was found in ca. 4:6 intensity ratio. 1H NMR
(CD2Cl2): d = 8.21 (dd, 2 × 4 H, ArH), 7.01–7.59 (m, 2 × 10
H, ArH), 6.65 (dd, JH,H = 3.6 Hz, JP,H = 32.2 Hz, 1 H, HC=C),
6.57 (dd, JH,H = 3.6 Hz, JP,H = 32.2 Hz, 1 H, HC=C), 5.52 (dd,
d = 72.0 (s, JP–Se = 340 Hz, JP=Se = 803 Hz), 70.7 (s, JP–Se
=
357 Hz, JP=Se = 789 Hz). 77Se NMR (CD2Cl2): d = 400.7 (d,
© Thieme Stuttgart · New York
Synlett 2012, 23, 1170–1174

1174
G. Hua et al.
LETTER
JP–Se = 340 Hz), 386.5 (d, JP–Se = 357 Hz), –177.8 (d, JP=Se
789 Hz), –191.1 (d, JP=Se = 803 Hz). MS (CI+): m/z = 493
=
3:4:2:2 extensity ratio. IR (KBr): 1657 (s, C=C), 1432 (s),
1226 (m), 1089 (s), 819 (m), 699(vs), 595 (m), 507 (s) cm–1.
1H NMR (CD2Cl2): d = 8.22–7.01 (m, 4 × 9 H, thienyl-H +
ArH), 6.65–6.94 (m, 4 × 2 H, thienyl-H), 5.65–5.75 (m, 4 ×
1 H, =CH), 3.29–3.29 (m, 4 × 1 H, SeCH). 13C NMR
(CD2Cl2): d = 144.2, 143.8, 143.6, 143.2, 138.9, 136.1,
135.2, 134.6, 133.7, 133.6, 133.0, 132.9, 132.7, 132.5,
132.4, 132.1, 131.7, 128.8, 128.3, 128.2, 128.0, 127.9,
127.3, 126.9, 125.2, 125.1, 123.7, 123.5, 44.5, 43.8, 43.3,
[M + H]+. MS (EI+) m/z = 492 [M]+. HRMS (EI+): m/z [M]+
calcd for C22H18FP76Se2: 483.9509; found: 483.9504.
Compound 5: yellow solid (403 mg) in 83% isolated yield.
Two stereoisomers were found in ca. 1:2 intensity ratio. IR
(KBr): 1598 (w, C=C), 1491 (m, C=C), 1434 (m, C=C),
1185 (w), 1165 (w), 1128 (w), 1088 (s), 939 (s), 764 (s), 745
(s), 688(vs), 630 (m), 595 (s), 506 (s, P=Se) cm–1. 1H NMR
(CDCl3): d = 7.47–7.63 (m, 2 × 2 H, ArH), 7.30–7.37 (m, 2
× 5 H, ArH), 7.12–7.21 (m, 2 × 4 H, ArH), 7.04–7.11 (m, 2
× 4 H, ArH), 6.93–6.96 (m, 2 × 2 H, ArH), 7.05 (d, J = 3.0
Hz, 1 H, CH), 6.95 (d, J = 3.0 Hz, 1 H, CH), 6.66 (dd,
3JH,H = 3.0 Hz, 3JP,H = 15.0 Hz, 1 H, CH), 6.36 (dd,
3JH,H = 3.0 Hz, 2JP,H = 32.0 Hz, 1 H, CH). 13C NMR (CDCl3):
d = 141.0, 136.0, 135.8, 133.1, 133.0, 132.6, 132.4, 132.0,
129.0, 128.8, 128.3, 128.2, 127.9, 127.8, 127.0, 125.2, 70.3
(d, 1JP,C = 29 Hz). 31P NMR (CDCl3): d = 70.3 (s, JP–Se = 338
Hz, JP=Se = 803 Hz), 69.9 (s, JP–Se = 350 Hz, JP=Se = 782 Hz).
77Se NMR (CDCl3): d = 374.0 (d, JP–Se = 338 Hz), 354.9 (d,
JP–Se = 350 Hz), –170.7 (d, JP=Se = 782 Hz), –188.0 (d,
JP=Se = 803 Hz). MS (ES+): m/z = 507 [M + Na]+. Anal. Calcd
for C23H19PSe2 (484.29): C, 57.04; H, 3.95. Found: C, 57.01;
H, 3.99.
41.0. 31P NMR (CD2Cl2): d = 71.1 (s, JP–Se = 336 Hz, JP=Se
810 Hz), 69.1 (s, JP–Se = 341 Hz, JP=Se = 792 Hz), 61.0 (s,
=
JP–Se = 377 Hz, JP=Se = 789 Hz), 60.5 (s, JP–Se = 393 Hz, JP=Se
= 777 Hz). 77Se NMR (CD2Cl2): d = 477.2 (d, JP–Se = 377
Hz), 412.7 (d, JP–Se = 341 Hz), 407.3 (d, JP–Se = 336 Hz),
398.5 (d, JP–Se = 393 Hz), –142.5 (d, JP=Se = 777 Hz), –166.4
(d, JP=Se = 789 Hz), –176.7 (d, JP=Se = 792 Hz), –203.3 (d,
JP=Se = 810 Hz). MS (EI+): m/z = 472 [M]+. HRMS (EI+):
m/z [M]+ calcd for C17H13PS274Se2: 459.8640; found:
459.8635.
General Procedure for Synthesis of Compounds 9 and 10
from the Selenation of Aromatic a,b-Unsaturated Enals:
A red solution of aromatic enal (1.0 mmol) and WR (0.54 g,
1.0 mmol) in anhyd toluene (20 mL) was refluxed for 7 h.
Red suspension disappeared and a pale brown solution along
with small amount of grey elemental selenium precipitate
was formed. Upon cooling to r.t. the mixture was dried in
evaporator and the residue was purified by silica gel column
(eluent: EtOAc–CH2Cl2, 1:5) to give compounds 9 and 10.
Compound 9: reddish yellow paste (600 mg) in 79%
isolated yield. 31P NMR spectrum revealed a mixture of four
stereoisomers in ca. 5:7:5:3 intensity ratio. IR (KBr): 1673
(s, C=C), 1491 (m), 1450 (m), 1434 (m), 1121 (m), 1088
(m), 961 (m), 764(vs), 693(vs), 591 (m), 511 (m)cm–1. 1H
NMR (CD2Cl2): d = 7.92–8.11 (m, 2 H, ArH), 7.07–7.58 (m,
8 H, ArH), 6.84–6.96 (m, 1 H, CH), 6.58–6.66 (m, 1 H, CH),
6.11–6.16 (m, 1 H, CH). 13C NMR (CD2Cl2): d = 137.0,
136.7, 134.0, 133.5, 133.4, 132.4, 132.2, 132.0, 131.6,
130.7, 129.6, 129.5, 129.0, 128.9, 128.7, 128.6, 128.4,
128.2, 128.1, 127.9, 127.5, 126.6, 32.0. 31P NMR (CD2Cl2):
Compound 6: brown solid (340 mg) in 67% yield. 31P NMR
spectrum revealed four stereoisomers in ca. 4:2:1:2 intensity
ratio. IR (KBr): 1691 (m, C=C), 1594 (m, C=C), 1518 (s,
C=C), 1434 (m), 1343 (s), 1089 (m), 851 (s), 689 (s), 596
(m), 508 cm–1. 1H NMR (CD2Cl2): d = 7.54–8.30 (m, 4 × 10
H, thienyl-H, ArH), 7.00–7.32 (m, 2 H, thienyl-H), 6.75–
6.93 (m, 4 × 1 H, =CH), 3.26–3.44 (m, 4 × 1 H, SeCH).
13C NMR (CD2Cl2): d = 150.4, 148.0, 147.7, 147.3,
143.5,142.1, 141.2, 139.2, 133.1, 133.0, 132.9, 132.7, 132.5,
132.0, 131.8, 129.1, 128.9, 128.8, 128.7, 128.6, 128.3,
128.1, 127.9, 127.8, 127.4, 127.1, 125.0, 124.6, 124.2,
123.9, 123.6, 67.6, 67.1, 61.8, 61.4, 41.1, 23.9. 31P NMR
(CD2Cl2): d = 73.7 (s, JP–Se = 331 Hz, JP=Se = 832 Hz), 71.8
(s, JP–Se = 340 Hz, JP=Se = 796 Hz), 61.0 (s, JP–Se = 366 Hz,
JP=Se = 793 Hz), 54.1 (s, JP–Se = 380 Hz, JP=Se = 782 Hz). 77Se
NMR (CD2Cl2): d = 487.1 (d, JP–Se = 381 Hz), 473.1 (d, JP–Se
= 365 Hz), 414.8 (d, JP–Se = 329 Hz), 405.6 (d, JP–Se = 341
Hz), –83.2 (d, JP=Se = 782 Hz), –161.5 (d, JP=Se = 793 Hz),
–166.7 (d, JP=Se = 796 Hz), –190.8 (d, JP=Se = 832 Hz). MS
(EI+): m/z = 511 [M]+. HRMS (EI+): m/z [M]+ calcd for
C19H14O2NPS74Se2: 498.8927; found: 498.8933.
Compound 7: dark red solid (250 mg)in 50% yield.
31P NMR spectrum revealed two stereoisomers in ca. 3:1
intensity ratio. IR (KBr): 1634 (s, C=C), 1557 (m, C=C),
1539 (m, C=C), 1470 (s), 1435 (m), 1408 (m), 1220 (m),
1071 (m), 781 (m), 748 (m), 686 (s)cm–1. 1H NMR (CD2Cl2):
d = 6.96–8.15 (m, 2 × 9 H, ArH), 6.41 (d, JP,H = 16.5 Hz, 1
H, CH), 6.40 (d, JP,H =16.5 Hz, 1 H, CH), 3.77–4.04 (m, 2 ×
1 H, CH), 3.37 (s, 6 H, Me), 2.94 (s, 6 H, Me). 13C NMR
(CD2Cl2): d = 142.6, 140.5, 138.2, 134.8, 132.7, 132.5,
132.3, 132.0, 131.4, 131.2, 130.2, 130.0, 128.8, 128.6,
127.2, 126.1, 61.1, 56.6, 37.1, 34.1. 31P NMR (CD2Cl2): d =
57.0 (s, JP–Se = 333 Hz, JP=Se = 787 Hz), 56.1 (s, JP–Se = 369
Hz, JP=Se = 785 Hz). 77Se NMR (CD2Cl2): d = 455.2 (d, JP–Se
= 369 Hz), 450.0 (d, JP–Se = 333 Hz), –131.2 (d, JP=Se = 785
Hz), –131.6 (d, JP=Se = 787 Hz). MS (EI+): m/z = 505 [M]+.
HRMS (EI+): m/z [M]+ calcd for C17H17BrPSe2: 504.8612;
found: 504.8615.
d = 72.6 (s, JP–Se = 326 Hz, JP=Se = 802 Hz), 72.1 (s, JP–Se
=
336 Hz, JP=Se = 784 Hz), 55.6 (s, JP–Se = 383 Hz, JP=Se = 770
Hz), 55.5 (s, JP–Se = 383 Hz, JP=Se = 767 Hz). MS (CI+):
m/z = 385 [M + H]+. HRMS (CI+): m/z [M + H]+ calcd for
C15H14PSe2: 384.9160; found: 384.9159.
Compound 10: greyish yellow solid (230 mg) in 56%
isolated yield. 31P NMR spectrum revealed a pair of
stereoisomers in ca. 1:2 intensity ratio. IR (KBr): 1597 (m,
C=C), 1490 (s), 1460 (s), 1434 (m), 1244(vs), 1026 (m), 750
(s) cm–1. 1H NMR (CD2Cl2): d = 7.02–8.20 (m, 2 × 6 H,
thienyl-H + ArH), 6.83–6.99 (m, 2 × 3 H, thienyl-H), 6.37–
6.51 (m, 2 × 1 H, =CH), 5.38–5.44 (m, 2 × 1 H, PCH), 3.87
(s, 3 H, OMe), 3.80 (s, 3 H, OMe), 3.29–3.45 (m, 2 × 1 H,
SeCH). 13C NMR (CD2Cl2): d = 157.4, 156.5, 148.0, 146.0,
133.7, 133.6, 132.0, 131.9, 131.7, 131.5, 129.7, 129.4,
129.3, 129.2, 129.1, 128.5, 128.3, 128.0, 127.9, 127.4,
127.3, 127.2, 127.0, 58.1, 57.6, 55.6, 55.5. 31P NMR
(CD2Cl2): d = 71.9 (s, JP–Se = 322 Hz, JP=Se = 798 Hz), 75.1
(s, JP–Se = 315 Hz, JP=Se = 782 Hz). 77Se NMR (CD2Cl2): d =
410.8 (d, JP–Se = 322 Hz), 381.6 (d, JP–Se = 315 Hz), –91.4 (d,
JP=Se = 782 Hz), –183.8 (d, JP=Se = 798 Hz). MS (CI+): m/z =
415 [M + H]+. HRMS (CI+): m/z [M + H]+ calcd for
C16H16OPSe2: 414.9265; found: 414.9264.
Compound 8: pale yellow solid (224 mg) in 48% yield.
Multi-NMR spectrum revealed four stereoisomers in ca.
(25) Sheldrick, G. M. SHELXL97. Acta Crystallogr., Sect A
2008, A64, 112.
Synlett 2012, 23, 1170–1174
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