Synthesis of organochalcogens stabilized by intramolecular non-bonded interactions of sterically unhindered 2-phenyl-2-oxazoline

Article abstract of DOI:10.1039/b312364b

The synthesis and characterization of low-valent organoselenium and -sulfur compounds incorporating sterically unhindered 2-phenyl-2-oxazoline are described. Organylselenenyl halides, RSeX (X = Cl, Br, I) were prepared from diselenide and the benzyl selenide derivative was synthesized by the reaction of in situ generated lithium arylselenolate, OxSe^-Li⁺ (Ox = 2-phenyl-2-oxazoline) with benzyl chloride. These compounds in general show strong Se...N intramolecular interactions as compared with the substituted oxazoline analogues. Bis[2-(2-oxazolinylphenyl)] disulfide and [2-(2-oxazolinyl)phenyl]benzyl sulfide were synthesized by the ortho-lithiation method and characterized by ¹H and ¹³C NMR spectroscopy. The S...N intramolecular interactions were confirmed by single crystal X-ray crystallography.

Full text of DOI:10.1039/b312364b

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P A P E R
Synthesis of organochalcogens stabilized by intramolecular non-
bonded interactions of sterically unhindered 2-phenyl-2-oxazoliney
Sangit Kumar,a Karuppasamy Kandasamy,a Harkesh B. Singh*a and Ray J. Butcherb
a
Department of Chemistry, Indian Institute of Technology, Bombay, Powai, Mumbai 400 076,
India. E-mail: chhbsia@chem.iitb.ac.in
Department of Chemistry, Howard University, Washington,, DC 20059, USA
b
Received (in Montpellier, France) 4th October 2003, Accepted 16th January 2004
First published as an Advance Article on the web 19th April 2004
The synthesis and characterization of low-valent organoselenium and -sulfur compounds incorporating
sterically unhindered 2-phenyl-2-oxazoline are described. Organylselenenyl halides, RSeX (X ¼ Cl, Br, I)
were prepared from diselenide and the benzyl selenide derivative was synthesized by the reaction of in situ
generated lithium arylselenolate, OxSeꢀLiþ (Ox ¼ 2-phenyl-2-oxazoline) with benzyl chloride. These
compounds in general show strong Seꢁ ꢁ ꢁN intramolecular interactions as compared with the substituted
oxazoline analogues. Bis[2-(2-oxazolinylphenyl)] disulfide and [2-(2-oxazolinyl)phenyl]benzyl sulfide were
1
synthesized by the ortho-lithiation method and characterized by H and 13C NMR spectroscopy.
The Sꢁ ꢁ ꢁN intramolecular interactions were confirmed by single crystal X-ray crystallography.
Introduction
The chemistry of intramolecularly coordinated organosele-
nium compounds has attracted a great deal of attention.1
Diorgano diselenides and other selenium derivatives are used
as: (a) electrophilic reagents in organic reactions such as meth-
oxyselenylation and aminoselenylation,2 (b) ligands for coordi-
nation chemistry3 and chiral or achiral catalysis, (c) ligands for
stabilization of MOCVD (metal-organic chemical vapor deposi-
tion) precursors4 and (d) as synthetic models of glutathione
peroxidase enzymes.5–7
Organoselenium compounds bearing oxazoline as the
coordinating group have attracted considerable attention.
Fukuzawa et al.8 have used bis[(S,S)-(isopropyl-2-oxzolin-2-
Chart 1 Diorganodiselenides having intramolecular Seꢁ ꢁ ꢁN inter-
yl)ferrocenyl] diselenide for asymmetric methoxyselenenyla-
tion of alkenes. Bolm et al.9 have also used chiral oxazoline
ferrocenyl diselenide for the catalytic asymmetric aryl transfer
to aldehyde, and recently Braga et al.10 have reported bis[(S)-
(4-isopropyloxazolinyl-2-phenyl)] diselenide as a ligand for
copper-catalyzed conjugate addition of Grignard reagents to
enones. Recently, our group has reported the glutathione per-
oxidase (GPx)-like activity of a series of diselenides having
intramolecular coordinating groups (1–5, Chart 1).6b,c It was
found that diselenides (1 and 2) having weak Seꢁ ꢁ ꢁN inter-
actions show high GPx-like activity whereas diselenides (3–5)
having a strong Seꢁ ꢁ ꢁN interaction did not show any activity.
To fine-tune the Seꢁ ꢁ ꢁN intramolecular interactions and
study the consequent GPx activity, we synthesized bis[2-(2-
oxazolinyl)phenyl] diselenide (6)7 incorporating the sterically
unhindered 2-phenyl-2-oxazoline and found that 6 showed
higher GPx activity than diselenides 4 and 5.
actions.
a-branched 2-phenyl-2-oxazolines. Synthesis of the disulfide
(11) and benzyl sulfide (13) analogues is also described and
the intramolecular Sꢁ ꢁ ꢁN interactions are compared with those
in related organosulfides.
Results and discussion
The precursor 2-phenyl-2-oxazoline (7)11 was prepared by fol-
lowing the literature method with minor modification. Disele-
nide (6) was obtained from 2-phenyl-2-oxazoline through the
lithiation route (Scheme 1).7 [2-(2-Oxazolinyl)phenyl]selenenyl
halides (14–16) were prepared from diselenide (6) by using
different halogenating reagents. The reaction of diselenide 6
with an equimolar amount of iodine led to the formation of
the novel [2-(2-oxazolinyl)phenyl]selenenyl iodide (16).12–14
Treatment of lithium arylselenolate (9) with an equimolar
amount of benzyl chloride gave the stable selenium benzyl
derivative (12).
In contrast to the synthesis of 6, the synthesis of the disulfide
analogue (11) proved to be difficult due to the higher stability
of the arylthiol intermediate produced by the hydrolysis of the
lithium arylthiolate and a vigorous oxidation by aqueous
K3Fe(CN)6 was required to convert the thiol to disulfide.
We report in this full paper the synthesis, solution and struc-
tural study of 6 along with a series of organoselenium
compounds derived from unhindered 2-phenyl-2-oxazoline.
The Seꢁ ꢁ ꢁN intramolecular interactions have been probed
both in solution and in the solid state and compared with
those observed in organoselenium compounds based on the
y Electronic supplementary information (ESI) available: 77Se NMR
spectrum of 14, molecular structure of 16 and packing diagram of
15. See http://www.rsc.org/suppdata/nj/b3/b312364b/
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
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earlier reported values of [2-(4,4-dimethyl-2-oxazolinyl)-
phenyl]benzyl selenide (420 ppm)14a and benzylic derivatives
of N-tert-butylbenzanilide (367 ppm).17
Mass spectra. The mass spectra of compounds 14 and 15
showed no peaks higher than the expected molecular mass,
indicating their monomeric nature. However, the mass spec-
trum of selenenyl iodide 16 shows a molecular ion peak at
m/z ¼ 452 due to formation of the diselenide (6).
X-Ray crystallographic studies
Structure of 6. An ORTEP view of 6 is shown in Fig. 1. The
selected bond lengths and angles are given in Table 2. The
coordination geometry around the selenium atom is nearly
T-shaped with each selenium atom bonded to selenium, carbon
and nitrogen atoms. The interesting feature of the structure is
the existence of Seꢁ ꢁ ꢁN interactions between the selenium and
Scheme 1 Synthetic routes to organoselenium/-sulfur compounds.
Reagents and conditions: (i) n-BuLi, Et2O or THF, ꢀ15 ꢂC; (ii) Se/S
powder, 5 h, 0 ꢂC; (iii) PhCH2Cl, 3 h, 0 ꢂC; (iv) aq. NaHCO3 and
O2 ; (v) SO2Cl2 , CCl4 , 0 ꢂC; (vi) Br2 , CCl4 , 0 ꢂC; (vii) I2 , CCl4 , r.t.
˚
nitrogen. The Se(1A)ꢁ ꢁ ꢁN(1A) [2.71(6) A] and Se(1B)ꢁ ꢁ ꢁN(1B)
˚
[2.76(6) A] distances are shorter than the sum of their van der
˚
Waals radii (3.45 A) and almost similar to the respective dis-
Reaction of OxSꢀLiþ with benzyl chloride gave benzyl sulfide
(13) in one pot.
6c,14d
˚
tances of reported diselenides (2–5; 2.79(6)–2.86(5) A].
Thus, Seꢁ ꢁ ꢁN distances in 6 indicate that the better GPx-like
activity of diselenide 6 than diselenides 4 and 5 is probably
due a steric effect (absence of an alkyl group in the oxazoline
ring) and not due to the nature of the Seꢁ ꢁ ꢁN interaction.7 In
the case of 6, the C(1A)–Se(1A)–Se(1B)–C(1B) torsion angle
is ꢀ79.5(3)ꢂ and thus indicates a ‘cisoid’ conformation.
Spectroscopic studies
1H NMR spectra. The 1H chemical shifts for all selenium
compounds investigated in this work exhibit a trend that is
indicative of ortho-selenation and an Seꢁ ꢁ ꢁN interaction (Table
1). The 1H chemical shifts for the organosulfur compounds (11
and 13) indicate a weaker (Sꢁ ꢁ ꢁN) interaction compared to the
selenium compounds. It is interesting to note that the signals
due to the –OCH2– protons are more affected than the corre-
sponding methylene protons in organoselenium derivatives
based on 4,4-dimethyl-2-phenyloxazoline and (R)-4-ethyl-4-
hydro-2-phenyloxazoline.14a,b
Structure of 15. A perspective view of the molecule of 15
is illustrated in Fig. 2. Selected bond distances and angles
are given in Table 2. The geometry around the selenium is
˚
T-shaped. The Nꢁ ꢁ ꢁSe intramolecular distance [1.98(2) A] is sig-
˚
nificantly shorter and the Se–Br [2.6998(4) A] distance is
longer than those reported for related selenenyl bromides.14a,b
In the crystal of 15, the intermolecular Seꢁ ꢁ ꢁSe distance
18
˚
[3.86(6) A] is comparable to the values reported for cyclic
˚
77Se NMR spectra. The chemical shifts for the organylsele-
nenyl chloride 14 (1019 ppm) and bromide 15 (985 ppm) are
shifted downfield more than the chemical shifts of the related
[2-(4,4-dimethyl-2-oxazolinyl)phenyl]selenenyl chloride (856
ppm),14a bromide (850 ppm) and (R)-[2-(4-ethyl-4-hydroox-
azolinyl)phenyl]selenenyl bromide (850 ppm).14b However,
these values are close to those of [2-(N-cyclohexyl-N-methyl-
aminomethyl)phenyl]selenium chloride (1050 ppm),15 -selenium
bromide (1010 ppm), [2-(N,N-dimethylaminomethyl)phenyl]-
selenium bromide (987 ppm),14d PhSeCl (1042 ppm) and
PhSeBr (869 ppm).16 On the other hand, the 77Se NMR chem-
ical shift of selenenyl iodide (16; 769 ppm) is almost the same
as those reported for similar organylselenenyl iodides (762
and 769 ppm).14a,b The 77Se chemical shift for the benzylic
compound 12 (376 ppm) is in close agreement with the
tetraselenadiynes (Seꢁ ꢁ ꢁSe ¼ 3.58–3.90 A).
Molecular structure of 16. The molecule of 16 is isostructural
with 15. Significant bond distances and angles are given in
Table 2. As was noted for 15, the Nꢁ ꢁ ꢁSe intermolecular dis-
˚
tance [2.01(4) A] in 16 is shorter and the Se–I distance
˚
[2.893(8) A] is longer than those in the reported related selene-
nyl iodides.14,19 In the packing of selenenyl halides 15 and 16
the molecules are self-associated. This may be attributed to
optimized dense packing of molecules, which may be facili-
tated by the planar arrangements of these selenenyl halides
(Fig. 3).
Molecular structure of 11. A PLUTON view of 11 with atom
numbering is shown in Fig. 4. Selected bond distances and
˚
angle are listed in Table 2. The S(1)ꢁ ꢁ ꢁN(1) [2.72(19) A] and
Table 1 1H NMR chemical shift for the methylene protons and 77Se
˚
S(2)ꢁ ꢁ ꢁN(2) [2.76(2) A] distances are shorter than those
NMR dataa
77Se NMRb
=
Compound
–CH2N
–CH2O–
1
6
4.06
4.25
4.24
4.33
4.15
4.38
4.43
4.30
4.44
4.47
4.45
4.47
4.45
4.50
5.07
4.82
–
465
–
11
12
13
14
15
16
376
–
1019
985
769
a
Chemical shift (ppm) measured in CDCl3 at room temperature.
Chemical shift relative to Me2Se
b
Fig. 1 Molecular structure of 6.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 6 4 0 – 6 4 5
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ꢂ
˚
Table 2 Significant bond lengths (A) and angles ( ) for organo-
selenium (6, 15 and 16) and -sulfur (11, 13) compounds
6
Se(1A)ꢁ ꢁ ꢁN(1A)
2.71(6)
2.343(13) N(1B)ꢁ ꢁ ꢁSe(1B)–
Se(1B)ꢁ ꢁ ꢁN(1B)
2.76(6)
168.28(15)
Se(1A)–Se(1B)
Se(1A)
N(1A)ꢁ ꢁ ꢁSe(1A)– 177.02(16) N(1A)ꢁ ꢁ ꢁSe(1A)–
76.10(2)
Se(1B)
C(1A)
C(1A)–Se(1A)–
Se(1B)–C(1B)
15
ꢀ79.5(3)
Seꢁ ꢁ ꢁN
1.98(2)
176.37(8)
3.86(6)
Se–Br
C(1)–Se–Br
2.6998(4)
95.57(9)
Nꢁ ꢁ ꢁSe–Br
Seꢁ ꢁ ꢁSe(_d)
16
Se(1)ꢁ ꢁ ꢁN(1)
Se(1)–I(1)
C(11)–Se(1)–I(1)
11
2.01(4)
2.8935(8) Se(2)–I(2)
Se(2)ꢁ ꢁ ꢁN(2)
2.04(4)
2.8513(8)
178.97(16)
96.97(16) N(1)ꢁ ꢁ ꢁSe(1)–I(1)
C(1A)–S(1A)
S(1A)–S(1B)
1.792(2) N(1B)ꢁ ꢁ ꢁS(1B)
2.0549(8) C(1A)–S(1A)–
S(1B)–C(1B)
2.76(2)
80.41(11)
Fig. 3 Packing diagram of 16.
N(1A)ꢁ ꢁ ꢁS(1A)
13
S–C(1)
2.72(19)
sulfur compounds (11, 13) derived from 7 when compared with
related analogues derived from a-branched 4,4-dimethyl-2-
phenyloxazoline, (R)-4-ethyl-4-hydro-2-phenyloxazoline and
N,N-dimethylbenzylamine (tert-amine) suggest that the substi-
tuents on the fourth position of the oxazoline ring decrease the
Seꢁ ꢁ ꢁN interactions. This observation is quite well-known for
bulky alkyl amines where a-branching of alkyl substituents
on nitrogen lowers its electron donor ability due to steric
effects.22 Thus, the absence of alkyl groups at the fourth posi-
tion in the present case may favor the donor ability of nitrogen
(B in Chart 2) and one may expect a stronger intramolecular
Seꢁ ꢁ ꢁN interaction in organoselenium compounds based on
2-phenyl-2-oxazoline (7).
1.774(3) Nꢁ ꢁ ꢁS–C(10)
1.827(3) C(1)–S–C(10)
2.81(3)
178.03(11)
103.04(13)
S–C(10)
Nꢁ ꢁ ꢁS
reported for bis[(4,4-dimethyl-2-phenyl)oxazoline] disulfide
˚
[S(1A)ꢁ ꢁ ꢁN(1A) ¼ 2.81(3)
A
and S(1B)ꢁ ꢁ ꢁN(1B) ¼ 2.78(3)
20
˚
˚
A]. The S(1A)–S(1B) bond length of 2.05(8) A is comparable
to that of the reported disulfide.20
Molecular structure of 13. A PLUTON view of 13 is shown
in Fig. 5 and selected bond distances and angles are listed in
Table 2. The structure of 13 is similar to the structure of the
sulfide analogue derived from 4,4-dimethyl-2-phenyloxazoline.
The sulfur is in a T-shaped environment with an angle C(1)–S–
C(10) ¼ 103.04(13) . The Sꢁ ꢁ ꢁN bond separation is 2.81(3) A.
The Nꢁ ꢁ ꢁS–C(10) bond angle [178.03(11)ꢂ] indicates a linear
arrangement. The Sꢁ ꢁ ꢁN intramolecular distance and Nꢁ ꢁ ꢁS–
C(10) bond angle are similar to those reported for [2-(4,4-
Summary
ꢂ
˚
From the results and their comparison with related organo-
selenium compounds, it is apparent that the strength of the
Seꢁ ꢁ ꢁN interactions depends on the steric effect of the ligands.
The strongest Seꢁ ꢁ ꢁN intramolecular interaction is observed
in the selenenyl bromide (15) compared with other compounds
in this study and related compounds reported in the literature.
dimethyl-2-oxazolinyl)phenyl]benzyl sulfide [Sꢁ ꢁ ꢁN ¼ 2.82(2)
21
ꢂ
˚
A; Sꢁ ꢁ ꢁN–C ¼ 179.05 ].
Intramolecular interactions. The stronger intramolecular
Se/Sꢁ ꢁ ꢁN interactions in organoselenium (6, 12, 14–16) and
Experimental section
General procedures
All reactions were carried out in inert atmosphere using nitro-
gen or argon with standard vacuum-line techniques. All sol-
vents were purified by following the literature methods and
freshly distilled prior to use.23 All the chemicals used (e.g., n-
butyllithium, E-Merck) were reagent grade and used as
Fig. 2 Molecular structure of 15.
Fig. 4 Molecular structure of 11.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
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the lithiated product was obtained. After the addition of sulfur
powder (0.32 g, 10 mmol) at 0 ꢂC, the reaction mixture was
allowed to reach room temperature and stirring was continued
for an additional 1 h. The reaction mixture was then poured
into a beaker containing a cold aqueous K3Fe(CN)6 (3.29 g,
10 mmol) solution. The red oily product was extracted with
ether and then washed with water. The organic phase was
separated, dried over Na2SO4 and filtered. The filtrate was
concentrated to give a white solid of the disulfide 11, which
was crystallized from CH2Cl2–CH3OH (2:1) as white plates.
Yield: 0.96 g (69%). M.p. 209–211 ꢂC. Anal. calcd for
C18H16N2O2S2 (356.46): C, 60.67, H, 4.52, N, 7.85; S, 18.00;
found: C, 60.32; H, 4.22; N, 8.07; S, 17.83%. 1H NMR
(CDCl3): d 4.24 (t, 4H), 4.45 (t, 4H), 7.17–7.28 (m, 2H),
7.30–7.38 (m, 2H), 7.72–7.78 (m, 2H), 7.85–7.92 (m, 2H), 13C
NMR (CDCl3):
130.03, 131.18, 138.19, 163.32. IR (KBr pellets): n 3050,
2941, 2905, 2840, 1663, 1630, 1586, 1460, 1052, 756 cmꢀ1
d 55.53, 66.99, 125.26, 125.63, 125.82,
.
Fig. 5 Molecular structure of 13.
[2-(2-Oxazolinyl)phenyl]benzyl selenide (12). To a solution of
7 (0.65 mL, 5 mmol) in dry THF (50 mL) was added n-BuLi
(3.4 mL, 5.5 mmol, 1.6 M solution in hexane) under N2 at
0 ꢂC. The mixture was stirred for 1 h at this temperature to give
the lithiated product. To this selenium powder (0.4 g, 5 mmol)
was added under a brisk flow of N2 and the reaction mixture
was stirred for 2 h. Benzyl chloride (0.6 mL, 5 mmol) was
added to the reaction mixture, which was allowed to come to
room temperature and stirring was continued for an additional
3 h. Standard work-up gave a yellowish oil of 12, which was
crystallized from CH2Cl2–hexane (1:1) to give a white crystal-
line solid. Yield: 1.3 g (82%). M.p. 124–127 ꢂC. Anal. calcd for
C16H15NOSe (316.16): C, 60.78, H, 4.78, N, 4.43; found: C,
received. Melting points were recorded in capillary tubes and
are uncorrected. The 1H, 13C and 77Se NMR spectra were
obtained at 300, 75.42 and 57.22 MHz, respectively, in CDCl3
on a Varian VXR 300S spectrometer. Chemical shifts are cited
with respect to SiMe4 (1H and 13C) and Me2Se (77Se) as inter-
nal and external standards, respectively. Elemental analysis
was determined with a Carlo–Erba model EA 1112 CHNS
analyzer. The IR spectra were recorded on a Bio-Rod FT-IR
spectrophotometer model FTS165 with KBr pellets or liquid
film. Fast atomic bombardment (FAB) mass spectra were
recorded at room temperature on a JEOL SX 102/DA-6000
mass spectrometer/data system with xenon (6 kV, 10 mV) as
the bombarding gas. The accelerating voltage was 10 kV. m-
Nitrobenzyl alcohol was used as the matrix with cation detec-
tion. For isotopes the value given is for the most intense peak.
GC-MS analyses were obtained on a Hewlett-Packard-1800
system equipped with a capillary column using electron
ionization detector.
1
60.07, H, 4.29, N, 4.42%. H NMR (CDCl3): d 4.11 (s, 2H),
4.33 (t, 2H), 4.47 (t, 2H), 7.21–7.35 (m, 6H), 7.40–7.42 (d,
1H), 7.84–7.86 (m, 2H). 13C NMR (CDCl3): d 30.78, 54.98,
66.94, 124.59, 125.62, 126.83, 127.84, 129.25, 129.67, 130.56,
130.89, 131.38, 136.93, 163.94. IR (KBr pellets): n 3062,
2966, 2927, 2895, 1648, 1462, 1353, 1264, 1149, 1097, 765 cmꢀ1
.
Syntheses
[2-(2-Oxazolinyl)phenyl]benzyl sulfide (13). The procedure
followed was the same as that used for the preparation of
compound 12, except that sulfur was added place of selenium.
The compound was recrystallized from a CHCl3–CH3OH (4:1)
mixture to give white plates of 13. Yield: 1.2 g (89%). M.p.
128–130 ꢂC. Anal. calcd for C16H15NOS (269.36): C, 71.36;
H, 5.61; N, 5.20; S, 11.89; found: C, 71.57, H, 5.74; N, 4.91;
S, 12.04%. 1H NMR (CDCl3): d 4.15 (t, 2H), 4.17 (s, 2H),
4.45 (t, 2H), 7.13–7.18 (m, 2H), 7.26–7.38 (m, 5H), 7.45 (d,
1H), 7.84 (d, 1H). 13C NMR (CDCl3): d 30.79, 55.59, 66.78,
124.20, 125.66, 126.09, 127.20, 127.49, 128.49, 129.04, 130.28,
130.74, 136.32, 139.64, 163.52. IR (KBr pellets): n 3050,
2-Phenyl-2-oxazoline (7). Ligand 7 was synthesized by fol-
lowing the literature method with slight modifications.11
A
stirred solution of benzonitrile (51.56 g, 0.5 mol) in chloroben-
zene was refluxed with ethanolamine (45.75 g, 0.75 mol) in the
presence of Cd(CH3COO)2ꢁ2H2O (0.66 g, 0.0025 mol) for 26 h.
The reaction residue was washed with water (100 mL) twice
and extracted back with CH2Cl2 , then dried over sodium sul-
fate. The solvent was evaporated and the colorless liquid of
7 was purified by vacuum distillation. Yield 65.42 g (89%).
1H NMR (CDCl3): d 4.06 (t, 2H) 4.44 (t, 2H), 7.36–7.52 (m,
3H), 7.92–7.98 (m, 2H). GC-MS (%): 147, Mþ (70), 105
(100), 103 (60) 77 (72), 51 (20). IR (KBr pellets): n 3057,
2942, 2897, 2860, 1656, 1486, 1450, 1354, 1274,1137, 936,
2923, 2854, 1682, 1657, 1586, 1572, 1028, 931, 743 cmꢀ1
.
792 cmꢀ1
.
[2-(2-Oxazolinyl)phenyl]selenenyl chloride (14). To a solution
of 6 (0.45 g, 1 mmol) in CCl4 (35 mL) at room temperature was
added a solution of SO2Cl2 (0.134 g, 1 mmol) in CCl4 . The
reaction mixture was stirred for 1.5 h at room temperature.
The resulting solution was concentrated to give a yellowish-
white, crystalline product. Yield: 0.43 g (83%). M.p. 210–
212 ꢂC. Anal. calcd for C9H8NOSeCl (260.48): C, 41.50; H,
Bis[2-(2-oxazolinyl)phenyl] disulfide (11). A stirred solution
of 2-phenyl-2-oxazoline (1.3 mL, 1.47 g, 10 mmol) in dry
THF (50 mL) was treated dropwise with a 1.6 M solution of
n-BuLi in hexane (6.4 mL, 10.2 mmol) under N2at 0 ꢂC. On
stirring the reaction mixture for 0.5 h at this temperature,
1
3.09; N, 5.37; found: C, 41.97; H, 3.11; N, 5.67%. H NMR
(CDCl3): d 4.38 (t, 2H), 4.50 (t, 2H), 7.23–7.28 (t, 1H), 7.29–
7.36 (t, 1H), 7.52–7.58 (d, 1H), 7.88–7.94 (d, 1H). FAB-MS:
m/z 263 (Mþ). IR (KBr pellets): n 3073, 2947, 2890, 1742,
1635, 1287, 1126, 720 cmꢀ1
.
[2-(2-Oxazolinyl)phenyl]selenenyl bromide (15). To a cold
solution of diselenide 6 (0.45 g, 1 mmol) in CCl4 (30 mL)
was added a solution of bromine (0.16 g, 1 mmol) in CCl4
Chart 2 Postulated contribution of the oxygen atom to resonance
stabilization of the oxazoline ring in compounds 6 and 11–16.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 6 4 0 – 6 4 5
643

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Table 3 Crystal data and structure refinement for organoselenium (6, 15 and 16) and -sulfur (11, 13) compounds
Compound
6
15
16
11
13
Empirical formula
Formula weight
Crystal system
Space group
C9H8NOSe
225.12
Triclinic
P-1
C9H8BrNOSe
305.03
Orthorhombic
Pbna
C18H16I2N2O2Se2
704.05
C18H16N2O2S2
356.45
C16H15NOS
269.35
Orthorhombic
P2(1)2(1)2(1)
5.6512(10)
7.9702(14)
30.441(5)
90
Monoclinic
P2(1)/c
15.416(3)
17.917(3)
7.8119(12)
90
Triclinic
P-1
˚
a/A
7.893(2)
7.901(2)
15.805(5)
85.564(5)
84.968(5)
62.449(5)
869.8(5)
4
7.3118(6)
15.2642(12)
17.2559(14)
90
7.7728(7))
7.7691(6)
15.5568(13)
85.376(5)
85.840(7)
63.251(7)
835.48(12)
2
˚
b/A
˚
c/A
a/ꢂ
b/ꢂ
g/ꢂ
90
90
102.816(4)
90
90
90
3
˚
U/A
1925.9(3)
8
2.104
2103.9(6)
4
2.223
1371.1(4)
4
1.305
Z
Dc/Mg mꢀ3
1.719
4.263
1.417
2.998
m/mmꢀ1
Temp. (K)
8.005
93(2)
6.464
293(2)
0.227
293(2)
8283
6322
293(2)
2434
293(2)
1033
1033
Total reflect.
Obsd. reflect.
Obsd reflect. [I > 2s(I)]
Rint
R(F) [I > 2s(I)]a
wR(F2) [I > 2s(I)]
10791
2379
18422
5193
2243
2434
1033
10 791
0.0751
0.0282
0.0515
P
18 422
0.0757
1033
0.0000
0.0708
0.1774
P
0.0146
0.0318
0.0323
0.0000
0.0306
0.0314
0.0342
0.0370
P
P
a
Definitions: R(F0) ¼ kF0| ꢀ |Fck/ | F0| and wR(F20) ¼ { [w(F02 ꢀ F2c)2]/ [w(Fc2)2}1/2
(25 mL). The addition was carried out dropwise over a period of
1 h and the solution then allowed to come to room temperature.
The solution obtained was concentrated to give yellow crystal-
line product 15, which was recrystallized from CHCl3–CH3OH
(2:1) to give reddish crystals. Yield: 0.48 g (79%). M.p. 189–
191 ꢂC. Anal. calcd for C9H8NOSeBr (304.94): C, 35.45; H,
factors were from common sources. Some details of the
structural and refinement are given in Table 3.z
Acknowledgements
1
We are grateful to the Department of Science and Technology
(DST), New Delhi for financial support. S. K. is grateful to the
Council of Scientific and Industrial Research (CSIR), Govern-
ment of India, New Delhi, for a Senior Research Fellowship.
Additional help from the Regional Sophisticated Instrumenta-
tion Center (RSIC), Indian Institute of Technology (IIT),
Bombay, for the 300 MHz NMR spectroscopy and the Tata
Fundamental Research Institute (TIFR), Bombay, for the
500 MHz NMR spectroscopy is gratefully acknowledged.
Thanks are due to RSIC, Central Drug Research Institute
(CDRI), Lucknow, for providing mass spectra.
2.64; N, 4.59; found: C, 34.71; H, 2.46; N, 4.85%. H NMR
(CDCl3): d 4.43 (t, 2H), 5.07 (t, 2H), 7.36–7.42 (t, 1H), 7.58–
7.68 (t, 1H), 8.18–8.27 (d, 1H), 8.74–8.84 (d, 1H). 13C NMR
(CDCl3): d 31.49, 42.31, 125.71, 126.43, 126.89, 130.63,
133.62, 141.43, 169.13. FAB-MS: m/z 305 (Mþ). IR (KBr pel-
lets): n 3068, 2927, 2857, 1718, 1622, 1283, 1123, 720 cmꢀ1
.
[2-(2-Oxazolinyl)phenyl]selenenyl iodide (16). To a cold solu-
tion of diselenide 6 (0.45 g, 1 mmol) in CCl4 (25 mL) was
added a solution of iodine (0.25 g, 1 mmol) in CCl4 . The addi-
tion was carried out dropwise over a period of 1 h and the
solution then allowed to come to room temperature with stir-
ring continued for an additional 2 h. The solution obtained
was concentrated to give a yellowish red crystalline product,
which was recrystallized from CHCl3–hexane (3:1) mixture
to give brick red needles of 16. Yield: 0.62 g (88%). M.p.
169–170 ꢂC. Anal. calcd for C9H8NOSeI (351.94): C, 30.72;
H, 2.29; N, 3.97; found: C, 30.80; H, 2.51; N, 3.79%. 1H
NMR (CDCl3): d 4.30 (t, 2H), 4.82 (t, 2H), 7.38–7.46 (t,
1H), 7.48–7.56 (t, 1H), 7.68–7.74 (d, 1H), 8.42–8.52 (d, 1H).
13C NMR (CDCl3 þ DMSO): d 50.59, 72.22, 122.37, 125.45,
126.40, 127.18, 132.70, 134.00, 170.23. FAB-MS: m/z 353
(Mþ), 453 (R2Se2 ; 6). IR (KBr pellets): n 3073, 2965, 2854,
References
1
2
G. Mugesh and H. B. Singh, Acc. Chem. Res., 2002, 35, 226.
(a) T. Wirth, Angew. Chem., Int. Ed., 2000, 39, 3740; (b) T. Wirth,
Organoselenium Chemistry, Springer-Verlag, Berlin, 2000, vol.
208; (c) T. G. Back, Organoselenium Chemistry, Oxford University
Press, Oxford, 1999 and references therein.
3
4
W. Levason, S. D. Orchard and G. Reid, Coord. Chem. Rev.,
2002, 225, 159 and reference therein.
(a) A. N. Gleizes, Chem. Vap. Deposition, 2000, 6, 155; (b) M.
Lazell, P. O’Brien, D. J. Otway and J.-H. Park, J. Chem. Soc.,
Dalton. Trans, 2000, 4479; (c) J. D. Sandman, L. Li, S. Tripathy,
J. C. Stark, L. A. Acampora, B. M. Foxman and L. A. Foxman,
Organometallics, 1994, 13, 348.
1735, 1663, 1283, 1123, 728 cmꢀ1
.
5
6
(a) T. G. Chasteen and R. Bentley, Chem. Rev., 2003, 103, 1; (b)
G. Mugesh, W. W. du Mont and H. Sies, Chem. Rev., 2001,
101, 2125.
(a) G. Mugesh and H. B. Singh, Chem. Soc. Rev., 2000, 29, 347;
(b) G. Mugesh, A. Panda, N. S. Punekar, H. B. Singh and R. J.
Butcher, Chem. Commun., 1998, 2227; (c) G. Mugesh, A. Panda,
N. S. Punekar, H. B. Singh and R. J. Butcher, J. Am. Chem. Soc.,
2001, 123, 839.
Crystallography
The diffraction measurements for compounds 6, 11, 13, 15 and
16 were performed on a Siemens R3m/V diffractometer with
˚
graphite-monochromated Mo/Ka radiation (l ¼ 0.7170 A).
The structures were determined by routine heavy-atom and
Fourier methods by using SHELXS-8624 and refined by full-
matrix least-squares with the non-hydrogen atoms anisotropic
and hydrogen with fixed isotropic thermal parameters of 0.07
7
G. Mugesh, A. Panda, S. Kumar, S. D. Apte, H. B. Singh and
R. Butcher, Organometallics, 2002, 21, 884.
2
25
˚
A by means of the SHELXL-97 program. Hydrogens were
partially located from difference electron-density maps and
the rest were fixed at predetermined positions. Scattering
z CCDC reference numbers 229425–229429. See http://www.rsc.org/
suppdata/nj/b3/b312364b/ for crystallographic data in .cif or other
electronic format.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
644
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 6 4 0 – 6 4 5

View Article Online
8
9
S.-I. Fukuzawa, K. Takahashi, H. Kato and H. Yamajaki, J. Org.
Chem., 1997, 62, 7711.
C. Bolm, M. Kesselgruber, A. Grenz, N. Hermanns and J. P.
Hildebrand, New J. Chem., 2001, 25, 13.
17 M. C. Fong and C. H. Schiesser, J. Org. Chem., 1997,
62, 3103.
18 (a) D. B. Werz, R. Gleiter and F. Rominger, J. Am. Chem. Soc.,
2002, 124, 10 638; (b) D. B. Werz, R. Gleiter and F. Rominger,
J. Org. Chem., 2002, 67, 4290.
19 W. W. du Mont, S. Kubiniok, K. Peters and H.-G. Von
Schnering, Angew. Chem., Int. Ed. Engl., 1987, 26, 780.
20 G. Mugesh, H. B. Singh and R. J. Butcher, Eur. J. Inorg. Chem.,
1999, 1229.
21 G. Mugesh, H. B. Singh and R. J. Butcher, J. Chem. Res., 1999,
(S) 416; (M) 1801.
22 J. E. Hueey, E. A. Keiter and R. L. Keiter, Inorganic Chemistry,
Harper Collins College Publisher, New York, 4th edn., 1993,
ch. 9, pp. 318–386.
23 D. D. Perrin, W. L. F. Armargo and D. R. Perrin, Purification
of Laboratory Chemicals, Pergamon, New York, 1980.
24 G. M. Sheldrick, SHELXS-86, Program for solution of crystal
structures, University of Go¨ttingen, Germany, 1986.
25 G. M. Sheldrick, SHELXL-97, Program for refinement of crystal
structures, University of Go¨ttingen, Germany, 1997.
10 A. L. Braga, S. J. N. Silva, D. S. Ludtke, R. L. Drekener, C. C.
Silveira, J. B. T. Rochaa and L. A. Wessjohann, Tetrahedron
Lett., 2002, 43, 7329.
11 H. WitteandW. Seeliger, Angew. Chem.,Int. Ed. Engl., 1972, 11, 287.
12 H. D. Maddox and J. D. Mc Cullough, Inorg. Chem., 1966, 5, 522.
13 T. Klapoetke and J. Passmore, Acc. Chem. Res., 1989, 22, 234.
14 (a) G. Mugesh, H. B. Singh and R. J. Butcher, Chem.-Eur. J.,
1999, 5, 1411; (b) G. Mugesh, H. B. Singh and R. J. Butcher,
Tetrahedron: Asymmetry, 1999, 10, 237; (c) A. Panda, G. Mugesh,
H. B. Singh and R. J. Butcher, Organometallics, 1999, 18, 1986;
(d ) R. Kaur, H. B. Singh and R. P. Patel, J. Chem. Soc., Dalton
Trans., 1996, 2719.
15 M. Iwaoka and S. Tomoda, J. Org. Chem., 1995, 60, 5299.
16 (a) M. Iwaoka and S. Tomoda, J. Am. Chem. Soc., 1996, 118,
8077; (b) W. Nakanishi, Y. Ikeda and H. Iwamura, Org. Magn.
Reson., 1982, 20, 117.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 6 4 0 – 6 4 5
645