Synthesis of 5-selenoxo-1,2,4-triazole-1-carboxylates from isoselenocyanates and azodicarboxylates

Article abstract of DOI:10.3987/COM-05-S(T)77

A mixture of an azodicarboxylate and triphenylphosphine in dichloromethane reacted with aryl isoselenocyanates (1) at room temperature to give 4,5-dihydro-5-selenoxo-1H-1,2,4-triazole-1-carboxylates (4a-f) in a one-pot reaction in good to excellent yields

Full text of DOI:10.3987/COM-05-S(T)77

HETEROCYCLES, Vol. 67, No. 2, 2006
749
HETEROCYCLES, Vol. 67, No. 2, 2006, pp. 749 - 762. © The Japan Institute of Heterocyclic Chemistry
Received, 22nd August, 2005, Accepted, 26th September, 2005, Published online, 30th September, 2005. COM-05-S(T)77
SYNTHESIS OF 5-SELENOXO-1,2,4-TRIAZOLE-1-
CARBOXYLATES FROM ISOSELENOCYANATES
AND AZODICARBOXYLATES
Francesco Favero,1 Geoffroy L. Sommen,2 Anthony Linden, and Heinz
Heimgartner*
Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse
190, CH-8057 Zürich, Switzerland; E-mail: heimgart@oci.unizh.ch
Dedicated to Professor Barry M. Trost at the occasion of his 65th birthday
Abstract – A mixture of an azodicarboxylate and triphenylphosphine in
dichloromethane reacted with aryl isoselenocyanates (1) at room
temperature
to
give
4,5-dihydro-5-selenoxo-1H-1,2,4-triazole-1-
carboxylates (4a-f) in a one-pot reaction in good to excellent yields. The
isoselenocyanates (1) have been prepared conveniently from formamides
by treatment with elemental selenium and phosgene according to Barton’s
procedure.
INTRODUCTION
Organoselenium compounds have continued to attract the attention of organic and medicinal
chemists owing to their unique biological and pharmaceutical activities.3 It has been shown that
the deficiency of selenium in human and animal organisms constitutes the basis of various
chronic diseases.4,5 Despite the high toxicity of many selenium compounds, organic derivatives
of selenium have been synthesized as antitumor,6,7 anticancer,8-10 anticarcinogenic,11 and other
medicinal preparations,12 as well as biologically active substances exhibiting antiviral,13
antimicrobial,14 antihypertensive,15 and fungicidal activities.16
The main drawbacks of some syntheses are the toxicity of commonly used selenium reagents

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HETEROCYCLES, Vol. 67, No. 2, 2006
and the instability of some intermediates. With the aim of developing syntheses of new
selenaheterocycles and heterocyclic selones by using less-toxic, conveniently accessible and
safely usable selenium reagents, we have investigated reactions with various
isoselenocyanates.17-29 They are materials of choice30 for the synthesis of numerous Se-
containing heterocycles,31 since they are easy to prepare and can be stored. We have already
shown that aryl isoselenocyanates (1) are very useful precursors for the introduction of
selenium into four, five, six and seven membered heterocycles like selenazetidines,25
selenazolones,29 selenazolidines,26 selenazines,26 perhydroselenazin-4- and -5-ones,29 and
selenazepanes.28 The general concept of these reactions is shown in Scheme 1: nucleophilic
addition of a suitably substituted compound (2) to the isoselenocyanate (1) to give a zwitterion
(3), which undergoes ring closure to yield selenaheterocycles (4) (see refs.20-23,26). An alternative
cyclization via the nitrogen atom leads to N-heterocyclic selones (5) (see refs.24,27).
Scheme 1
NAr
Se
Nu
ArN
Se
n
Base
NuH
4
Nu
N
C
Se
+
X
X
X
n
Ar
n
Se
Ar
1
2
3
N
Nu
n
5
As a continuation of our studies, we investigated the reaction of isoselenocyanates with diethyl
azodicarboxylate (6) and triphenylphosphine under Mitsunobu conditions. This reaction was
expected to give either 1,3,4-selenatriazole or 1,2,4-triazoleselone derivatives.32 To the best of
our knowledge, only a few 1,2,4-triazoleselones34 and their isomeric 1,2,4-triazoleselenols35
have been described. The main synthesis starts from a triazole, which is a good precursor for
the preparation of the carbene 1,2,4-triazol-3-ylidene.36 The latter reacts with elemental
selenium by forming the carbon-selenium double bond.37
Isoselenocyanates have already been used for the synthesis of mesoionic 1,2,4-triazolo-3-
selones.38 This preparation, published in 1976 by Egorochkin39 and in 2000 by Miller,40 was

HETEROCYCLES, Vol. 67, No. 2, 2006
751
carried out by reacting 1,1-diacylhydrazines with an isoselenocyanate in the presence of
triethylamine in boiling THF.
RESULTS AND DISCUSSION
Equimolar amounts of diethyl azodicarboxylate (6, DEAD) and triphenylphosphine (Ph3P) were
dissolved in dichloromethane, and the pale yellow solution was stirred for 30 min at 0°C. Then,
an equimolar amount of an aryl isoselenocyanate (1), which had been prepared conveniently by
a slightly modified Barton procedure41 from the corresponding N-arylformamide by treatment
with phosgene and elemental selenium, was added and the mixture stirred at room temperature
overnight. After evaporation of the solvent, the crude products were obtained as mixtures with
triphenylphospine oxide (Ph3PO; TLC detection), and separation by column chromatography
(SiO2, hexane/ethyl acetate) was necessary to get the ethyl 5-selenoxo-1H-1,2,4-triazole-1-
carboxylates (7a-e) (Scheme 2, Table 1). It has to be noted that this purification process is not
easy. A side-product always polluted the final product, and only trituration with diethyl ether or
dichloromethane and recrystallization from ethyl acetate led to pure 7.42
Scheme 2
CO2Et
CO2Et
N
N
CH2Cl2
N
N
PPh3
Ar NCSe
+
+
EtO
Se
N
EtO2C
N2 / rt / 15 h
Ar
6a
1
7
Ar = Ph, 4-Br-C6H4, 4-Cl-C6H4, 4-F-C6H4, 4-Me-C6H4
The structure of the products (7) was determined on the basis of their elemental analyses and
spectroscopic data. The IR spectra (KBr) show two strong bands at 1765-1773 and 1619-1625
cm-1 for the carboxylate and the C=N group, respectively. In the 13C-NMR spectra (CDCl3),
indicative absorptions for CO2Et, C(5)=Se, and C(3) appear at ca. 167, 156, and 148 ppm,
respectively. The ESI-MS spectra show the characteristic sets of the selenium isotope peaks for
[M+Na]+. Finally, the structure of 7e was established by an X-Ray crystal-structure
determination (Figure 1).
The five-membered ring of 7e is planar and the attached atoms Se(1), C(6), O(3), and C(5)

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HETEROCYCLES, Vol. 67, No. 2, 2006
deviate only slightly from the ring plane (maximum derivation is 0.148(2) Å for C(6)). Whereas
the ethoxy group at C(3) is co-planar with the heterocycle and the ester group, with the
exception of the terminal CH3 group, is only slightly twisted out of the heterocyclic ring plane
(angle between the planes is 8.1(1)°), the benzene ring at N(2) is oriented almost orthogonal to
the plane of the heterocyclic ring (angle between the planes is 74.2(1)°).
Table 1. Preparation of Triazole Derivatives (7) from Isoselenocyanates (1)
Entry
Ar
4
Yield (%)
81
CO2Et
Se
N
N
EtO
N
a
Ph
CO2Et
Se
N
N
EtO
N
b
c
4-Br-C6H4
82
97
Br
CO2Et
Se
N
N
EtO
N
4-Cl-C6H4
Cl
CO2Et
Se
N
N
EtO
N
d
e
4-F-C6H4
84
78
F
CO2Et
Se
N
N
EtO
N
4-Me-C6H4
Me

HETEROCYCLES, Vol. 67, No. 2, 2006
753
Figure 1. ORTEP plot45 of the molecular structure of 7e (arbitrary numbering of atoms; 50%
probability ellipsoids).
Scheme 3
CO2Et
Ph3P
CO2Et
N
N
PPh3
N
N
+
EtO2C
EtO2C
6a
8
Ar NCSe
1
Ph3P
CO2Et
CO2Et
N
N
Ph3P
O
N
O
N
Se
Se
10
N
EtO
EtO
Ar
N
Ar
9
CO2Et
CO2Et
Se
N
_ Ph3P=O
N N
Ph3P
O
N
Se
EtO
N
N
EtO
11
Ar
Ar
7

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HETEROCYCLES, Vol. 67, No. 2, 2006
A likely reaction mechanism for the formation of 7 is proposed in Scheme 3. The addition of
Ph3P onto the azodicarboxylate (6) generates the zwitterion (8), which, as a nucleophile, attacks
the isoselenocyanate (1) to give 9. Ring closure by nucleophilic addition of the N-atom at the
ester group leads to 10, and elimination of Ph3PO via the intermediate (11) yields the product
(7).
The use of the system diethyl azodicarboxylate (oxidant)/Ph3P (reducing agent) is well
established46 and is known as the Mitsunobu reaction47 when the reactant is an alcohol. The
betaine (8) is the initially formed intermediate in all cases and it reacts with the alcohol. In the
present case, this intermediate reacts as a nucleophile with the strongly electrophilic
isoselenocyanate (1).
Similar to the reaction with 6a, treatment of 4-bromophenyl isoselenocyanate (1b) with bis(tert-
butyl) azodicarboxylate (6b) and Ph3P gave the triazoloselone (7f) in almost quantitative yield.
This product was transformed into the 3-tert-butoxy-4,5-dihydro-1H-1,2,4-triazole-5-selone (12)
by decarboxylation with trifluoroacetic acid at room temperature in quantitative yield (Scheme
4).
Scheme 4
CO2Bu-t
N
N
CO2Bu-t
t-BuO2C
6b
N
N
N
NH
CF3COOH
+
PPh3
t-BuO
Se
t-BuO
Se
N
N
Ar
Ar
+
7f
12
Ar NCSe
1b
Ar
= 4
-Br
-C
H
In conclusion, we have shown that aryl isoselenocyanates (1) under Mitsunobu conditions can
be applied for the synthesis of 5-selenoxo-1,2,4-triazole derivatives in a one-pot procedure.
EXPERIMENTAL
General remarks. TLC: silica gel 60 F254 plates (0.25 mm, Merck). Column chromatography

HETEROCYCLES, Vol. 67, No. 2, 2006
755
(CC): silica gel 60 (0.040–0.063 mesh, Merck). Melting points: Büchi B-540 apparatus, in a
capillary, uncorrected. IR spectra: Perkin-Elmer 1600-FT-IR spectrometer; in KBr, absorptions
1
in cm-1. H-NMR (300 MHz) and 13C-NMR (75 MHz) spectra: Bruker ARX-300 instrument, in
CDCl3; chemical shifts in ppm, coupling constants J in Hz. EI-MS: Finnigan SSQ-700
instrument.
Starting materials. Diethyl and bis(tert-butyl) azidodicarboxylate (6a and 6b) and
triphenylphosphine (Ph3P) are commercially available (Fluka). Isoselenocyanates were
prepared according to Barton’s procedure41 starting from the corresponding formamides.
Formanilide was purchased (Fluka), N-(4-chlorophenyl)-, N-(4-bromophenyl)-, N-(4-
fluorophenyl)-, and N-(4-methylphenyl)formamide were prepared from the respective anilines
and 95% formic acid. The solution was heated to reflux for 30 min and evaporated to dryness in
vacuo. The residue was dissolved in ether (Et2O) and washed with diluted acetic acid (5%),
water and aqueous NaHCO3 (5%). The aqueous layer was extracted with Et2O, the combined
organic extracts were dried with MgSO4 and evaporated under reduced pressure. The crude
products were purified by recrystallization in ethanol/water.
Synthesis of 3-alkoxy-4,5-dihydro-5-selenoxo-1H-1,2,4-triazole-1-carboxylates (7a-d).
General procedure. A 25 mL round-bottom flask equipped with magnetic stirrer and condenser
was charged with a mixture of diethyl or bis(tert-butyl) azodicarboxylate (6a and 6b,
respectively) (0.92 mL, 2.0 mmol) and Ph3P (524 mg, 2.0 mmol) in dichloromethane (20 mL).
The mixture was stirred under an N2-atmosphere at 0°C (ice bath) for 30 min. An
isoselenocyanate (1, 2.0 mmol) was added in one portion, the mixture was stirred for 15 h at rt,
and evaporated to dryness under reduced pressure. The crude product was purified by column
chromatography on SiO2 using hexane/ethyl acetate (AcOEt; 100/0 to 50/50) as eluant and
recrystallization in AcOEt.
Ethyl 3-ethoxy-4,5-dihydro-4-phenyl-5-selenoxo-1H-1,2,4-triazole-1-carboxylate (7a). Yield: 552
mg (81%). Yellowish crystals; mp 142-144°C (AcOEt). IR: 3422w (br), 2981w, 2931w, 1773s,
1619s, 1595w, 1501w, 1451m, 1386m, 1368m, 1328s, 1308s, 1220s, 1175w, 1155w, 1109w,
1088w, 1066w, 1028m, 1005m, 979w, 902w, 861w, 847w, 776w, 710w, 689w. 1H-NMR: 1.36 (t,
J = 7.1, CH3); 1.49 (t, J = 7.1, CH3); 4.49-4.62 (m, 2 CH2); 7.35 (d, J = 8.1, 2 arom. H); 7.52-7.59
(m, 3 arom. H). 13C-NMR: 14.0 (CH3); 14.1 (CH3); 65.0 (CH2); 68.5 (CH2); 128.1 (2 arom. CH);

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HETEROCYCLES, Vol. 67, No. 2, 2006
129.4 (2 arom. CH); 130.0 (1 arom. CH); 132.6, 148.2 (1 arom. C, C(3)); 156.3 (C=Se); 167.8
(C=O). ESI-MS: 360 (14), 361 (13), 362 (52), 363 (3), 364 (100, [M+Na]+), 365 (11), 366 (15).
Anal. Calcd for C13H15N3O3Se: C, 45.89; H, 4.44; N, 11.86. Found: C, 45.58; H, 4.58; N, 12.64.
Ethyl 4-(4-bromophenyl)-3-ethoxy-4,5-dihydro-5-selenoxo-1H-1,2,4-triazole-1-carboxylate (7b).
Yield: 686 mg (82%). Yellowish crystals; mp 147-149°C (AcOEt). IR: 3444w (br), 2982w,
2935w, 1755s, 1718m, 1638s, 1591w, 1493m, 1451m, 1392m, 1366m, 1327s, 1303s, 1286s,
1
1215w, 1170w, 1154w, 1104w, 1068w, 1030m, 1011m, 988w, 909w, 850w, 754w, 711w. H-
NMR: 1.31 (t, J = 7.1, CH3); 1.41 (t, J = 7.1, CH3); 4.41-4.51 (m, 2 CH2); 7.20, 7.58 (AA’BB’, J ≈
8, 4 arom. H). 13C-NMR: 14.1 (CH3); 14.3 (CH3); 65.1 (CH2); 68.7 (CH2); 124.2 (1 arom. C); 129.8
(2 arom. CH); 132.7 (2 arom. CH); 131.5, 148.9 (1 arom. C, C(3)); 155.6 (C=Se); 166.8 (C=O).
ESI-MS: 438 (15), 439 (12), 440 (55), 441 (4), 442 (100, [M+Na]+), 443 (14), 444 (12). Anal.
Calcd for C13H14N3O3BrSe: C, 37.25; H, 3.37; N, 10.03. Found: C, 37.12; H, 3.23; N, 9.99.
Ethyl 4-(4-chlorophenyl)-3-ethoxy-4,5-dihydro-5-selenoxo-1H-1,2,4-triazole-1-carboxylate (7c).
Yield: 726 mg (97%). Yellowish crystals; mp 142-144°C (AcOEt). IR: 3442w (br), 2982w, 1765s,
1625s, 1495m, 1469w, 1442w, 1373m, 1310s, 1289s, 1218s, 1173w, 1148w, 1089m, 1025m,
977m, 907w, 836w, 753w, 703w. 1H-NMR: 1.31 (t, J = 7.1Hz, CH3); 1.41 (t, J = 7.1, CH3); 4.39-
13
4.51 (m, 2 CH2); 7.24, 7.43 (AA’BB’, J ≈ 8, 2H, 4 arom. H). C-NMR: 14.1 (CH3); 14.3 (CH3);
65.1 (CH2); 68.7 (CH2); 124.6 1 arom. C); 129.5 (2 arom. CH); 129.7 (2 arom. CH); 131.0, 148.9
(1 arom. C, C(3)); 155.6 (C=Se); 166.9 (C=O). ESI-MS: 394 (13), 395 (14), 396 (51), 397 (4),
398 (100, [M+Na]+), 399 (18), 400 (49). Anal. Calcd for C13H14N3O3ClSe: C, 41.67; H, 3.77; N,
11.21. Found: C, 41.63; H, 3.84; N, 11.34.
Ethyl 3-ethoxy-4-(4-fluorophenyl)-4,5-dihydro-5-selenoxo-1H-1,2,4-triazole-1-carboxylate (7d).
Yield: 603 mg (84%). Yellowish crystals; mp 151-153°C (AcOEt). IR: 3442w (br), 3085w,
2982w, 1769s, 1621s, 1512s, 1475w, 1454m, 1386m, 1367m, 1311s, 1290s, 1216s, 1171w,
1150w, 1112w, 1088w, 1063m, 1024m, 1004w, 977m, 905w, 853m, 821w, 759w, 725w, 711w,
635w, 622m. 1H-NMR: 1.35 (t, J = 7.1, CH3); 1.49 (t, J = 7.1, CH3); 4.41-4.51 (m, 2 CH2); 6.95,
7.19 (AA’BB’, J ≈ 8, 4 arom. H). 13C-NMR: 14.0 (CH3); 14.3 (CH3); 65.1 (CH2); 68.6 (CH2); 116.4
2
(2 arom. CH, JC,F = 23); 130.1 (2 arom. CH); 128.4, 148.9 (1 arom. C, C(3)); 155.8 (C=Se);
1
162.3 (CF, JC,F = 249); 167.1 (C=O). ESI-MS: 378 (15), 379 (12), 380 (55), 381 (4), 382 (100,
[M+Na]+), 383 (15), 384 (17). Anal. Calcd for C13H14N3O3FSe: C, 43.59; H, 3.94; N, 11.73. Found:

HETEROCYCLES, Vol. 67, No. 2, 2006
757
C, 43.37; H, 4.00; N, 11.88.
Ethyl 3-ethoxy-4,5-dihydro-4-(4-methylphenyl)-5-selenoxo-1H-1,2,4-triazole-1-carboxylate (7e).
Yield: 554 mg (78%). Yellowish crystals; mp 120-122°C (AcOEt). IR: 3442w (br), 2979w,
2956w, 1768s, 1619s, 1514m, 1477w, 1454m, 1389m, 1368m, 1327s, 1307s, 1294s, 1220s,
1173w, 1152w, 1109w, 1099w, 1064w, 1029m, 981w, 905w, 850w, 817w, 753w, 712w, 622w.
1H-NMR: 1.37 (t, J = 7.1, CH3); 1.49 (t, J = 7.1, CH3); 2.43 (s, CH3); 4.48-4.60 (m, 2 CH2); 7.22,
7.34 (AA’BB’, J ≈ 8, 4 arom. H). 13C-NMR: 14.0 (CH3); 14.3 (CH3); 21.3 (CH3); 65.0 (CH2); 68.4
(CH2); 127.7 (2 arom. CH); 130.0 (2 arom. CH); 127.3, 140.2 (1 arom. C, C(3)); 149.0 (1 arom.
C); 156.0 (C=Se); 167.1 (C=O). ESI-MS: 374 (12), 375 (14), 376 (48), 377 (4), 378 (100,
[M+Na]+), 379 (11), 380 (13), 733 (3). Anal. Calcd for C14H17N3O3Se: C, 47.46; H, 4.84; N, 11.86.
Found: C, 47.25; H, 4.85; N, 11.85.
tert-Butyl
3-tert-butoxy-4-(4-bromophenyl)-4,5-dihydro-5-selenoxo-1H-1,2,4-triazole-1-
carboxylate (7f). Yield: 855 mg (90%). Yellowish crystals; mp 118-120°C (AcOEt). IR: 3443w
(br), 2985w, 2931w, 1764s, 1701w, 1612s, 1488m, 1453w, 1408w, 1372m, 1337m, 1320s,
1
1297m, 1278s, 1223m, 1143s, 1065w, 1000m, 895w, 848m, 836m, 804w, 761w, 655w. H-
NMR: 1.53 (s, 3 CH3); 1.67 (s, 3 CH3); 7.21, 7.62 (AA’BB’, J ≈ 8, 4 arom. H). 13C-NMR: 27.6 (3
CH3); 27.8 (3 CH3); 86.6, 88.1 (2 C); 123.8 (1 arom. C); 129.8 (2 arom. CH); 132.5 (2 arom.
CH); 132.1, 147.1 (1 arom. C, C(3)); 153.5 (C=Se); 165.1 (C=O). ESI-MS: 494 (17), 495 (15),
496 (55), 497 (25), 498 (100, [M+Na]+), 499 (18), 500 (75), 501 (12), 502 (10). Anal. Calcd for
C17H22N3O3BrSe: C, 42.96; H, 4.67; N, 8.83. Found: C, 43.22; H, 4.95; N, 9.15.
Decarboxylation of 7f. 3-tert-Butoxy-4-(4-bromophenyl)-4,5-dihydro-1H-1,2,4-triazole-5-selone
(12). Yield: 713 mg (95%). Yellowish crystals; mp 235-237°C (AcOEt). IR: 3329w (br), 3088w,
2986w, 1612s, 1488m, 1410w, 1374m, 1343m, 1325s, 1298m, 1278s, 1222m, 1140s, 1078w,
998m, 889w, 845m, 831m, 751w. 1H-NMR: 1.52 (s, 3 CH3); 4.36 (br s, NH); 7.19, 7.64 (AA’BB’,
13
J ≈ 8, 4 arom. H). C-NMR: 31.6 (3 CH3); 86.5 (C); 121.5 (1 arom. C); 129.2 (2 arom. CH);
131.7 (2 arom. CH); 132.1, 146.0 (1 arom. C, C(3)); 153.1 (C=Se). ESI-MS: 394 (16), 395 (14),
396 (57), 397 (28), 398 (100, [M+Na]+), 399 (17), 400 (75), 401 (10), 402 (12). Anal. Calcd for
C17H22N3O3BrSe: C, 38.42; H, 3.76; N, 11.20. Found: C, 38.54; H, 3.57; N, 11.56.
X-Ray Crystal-Structure Determination of 7e (see Table 2 and Figure 1).48 All measurements

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HETEROCYCLES, Vol. 67, No. 2, 2006
were made on a Nonius KappaCCD area-detector diffractometer49 using graphite-
monochromated MoKα radiation (λ 0.71073 Å) and an Oxford Cryosystems Cryostream 700
cooler. The data collection and refinement parameters are given in Table 1, and a view of the
molecule is shown in Figure 1. Data reduction was performed with HKL Denzo and Scalepack.50
The intensities were corrected for Lorentz and polarization effects, and an absorption correction
based on the multi-scan method51 was applied. Equivalent reflections were merged. The
structure was solved by direct methods using SHELXS97,52 which revealed the positions of all
non-hydrogen atoms. The non-hydrogen atoms were refined anisotropically. All of the H-atoms
were placed in geometrically calculated positions and refined using a riding model where each
H-atom was assigned a fixed isotropic displacement parameter with a value equal to 1.2U of
eq
its parent atom (1.5U for the methyl groups). Refinement of the structure was carried out on
eq
2
2
2
F 2 using full-matrix least-squares procedures, which minimized the function Σw(Fo – Fc ) . A
correction for secondary extinction was applied. Neutral atom scattering factors for non-
hydrogen atoms were taken from ref.,53 and the scattering factors for H-atoms were taken from
ref.54 Anomalous dispersion effects were included in Fc;55 the values for f ' and f " were those of
ref.56 The values of the mass attenuation coefficients are those of ref.57 All calculations were
performed using the SHELXL9758 program.
ACKNOWLEDGMENTS
We thank the analytical services of our institute for NMR and MS spectra and elemental
analyses, and Miss S. Blumentritt for her assistance with the determination of the crystal
structure. Financial support of this work by the Dr. Helmut Legerlotz-Foundation and F.
Hoffmann-La Roche AG, Basel, is gratefully acknowledged.
REFERENCES AND NOTES
1. Stay at the University of Zürich (5.–7. 2005; trainee project).
2. Postdoctoral stay at the University of Zürich (2004–2005).
3. M. Koketsu and H. Ishihara, Curr. Org. Chem., 2003, 7, 175.
4. R. J. Shamberger, ‘Biochemistry of Selenium’, Plenum Press, New York, 1983.
5. E. M. Alissa, S. M. Bahijri, and G. A. Ferns, Med. Sci. Monit., 2003, 9, RA9.
6. P. C. Srivastava and R. K. Robins, J. Med. Chem., 1983, 26, 445.

HETEROCYCLES, Vol. 67, No. 2, 2006
759
Table 2. Crystallographic Data of Compound (7e)
Crystallized from
Empirical formula
CH Cl
2 2
C H N O Se
14 17 3 3
-1
Formula weight [g mol ]
354.21
Crystal color, habit
yellow, tablet
0.10 × 0.17 × 0.28
160(1)
Crystal dimensions [mm]
Temperature [K]
Crystal system
monoclinic
C2/c
Space group
Z
8
Reflections for cell determination
22257
2θ range for cell determination [°]
4–55
Unit cell parameters
a [Å]
b [Å]
c [Å]
β [°]
11.2907(3)
20.2786(6)
14.3222(3)
112.352(2)
3
V [Å ]
3032.8(1)
1.551
-3
D [g cm ]
x
-1
µ(MoKα) [mm ]
2.488
φ and ω
55
Scan type
2θ
[°]
(max)
Transmission factors (min; max)
Total reflections measured
Symmetry independent reflections
Reflections with I > 2σ(I)
0.667; 0.788
30892
3481
2790
Reflections used in refinement
Parameters refined
3481
194
Final : R(F) [I > 2σ(I) reflections]
0.0318
0.0871
2
wR(F ) (all data)
2
2
2
-1
2
2
Weights: w = [σ (F ) + (0.0494P) + 1.3898P] where P = (F + 2F )/3
o
o
c
Goodness of fit
Secondary extinction coefficient
Final ∆ /σ
1.038
0.0010(2)
0.001
max
-3
∆ρ (max; min) [e Å ]
0.51; –0.63

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