Diaryl Diselenides
J. Am. Chem. Soc., Vol. 123, No. 5, 2001 849
and oxygen was passed at a moderate rate for 1 h. The solution was
filtered, dried, and evaporated to give a brown oil. The crude product
was chromatographed on a silica gel column. The unreacted ferrocene
was eluted with hexane and 17 was eluted with a 2:1 hexane:CH2Cl2
mixture. Slow evaporation of the CH2Cl2 solution gave red crystals of
the desired compound. Yield 0.65 g (20%); mp 122-124 °C (lit.18 mp
126 °C); 77Se NMR (CDCl3) δ 576.7. Anal. Calcd for C26H32Fe2N2-
Se2: C, 48.63; H, 5.02; N, 4.36. Found: C, 48.62; H, 5.13; N, 4.25.
1H and 13C NMR data are in accordance with the literature values.18
Synthesis of bis[2-(4,4-dimethyl-2-oxazolinyl)phenyl]diselenide
(20): A stirred solution of 4,4-dimethyl-2-phenyloxazoline, (1.78 g,
10.16 mmol) in dry hexane (75 mL) was treated dropwise with a 1.6
M solution of n-BuLi in hexane (6.88 mL, 11.01 mmol) via syringe
under N2 at 0 °C. On stirring for 1 h at room temperature the white
precipitate of the lithiated product was obtained. The solvent was
removed by syringe and 50 mL of dry ether was added. The solution
was cooled to 0 °C, selenium powder (0.79, 10.01 mmol) was added,
and stirring was continued for an additional 2 h at 0 °C. The reaction
mixture was then removed from the N2 line and poured into a beaker
containing cold aqueous NaHCO3, and O2 was passed at a moderate
rate for 15 min. The organic phase was separated, dried over Na2SO4,
and filtered. The filtrate was evaporated to dryness to give a yellow
oil. The crystalline solid of the desired compound (20) was obtained
upon cooling. The compound was recrystallized from a chloroform/
methanol mixture to give pale yellow crystals. Yield 1.54 g (60%);
mp 158-160 °C; IR (KBr) 2935, 1649, 1561, 1468, 1433, 1386, 1319,
Table 4. Crystal Data and Structure Refinement for 12, 18, and 20
12
C18H18O4Se2 C28H36N2Se2 C22H24N2O2Se2
456.24 670.21 506.35
monoclinic orthorhombic rhombohedral
18
20
empirical formula
fw
crystal system
space group
a (Å)
P21/c
P212121
10.7903(11) 33.198(4)
15.1341(12) 33.198(4)
R3
8.9690(7)
12.5676(9)
b (Å)
c (Å)
15.6444(12) 17.7815(14) 10.564(2)
R (deg)
90
95.293(6)
90
90
90
90
90
90
120
â (deg)
γ (deg)
V (Å3)
1755.9(2)
4
1.726
4.230
2903.7(4)
4
1.533
3.524
4597
0.0511
0.0870
10083(2)
18
1.501
3.319
4884
0.0500
0.0837
Z
D(calcd) (Mg/m3)
abs coeff (mm-1
)
obsd reflens [I > 2σ] 3436
final R(F) [I > 2σ(I)]a 0.0455
wR(F2) indices
[I > 2σ(I)]
0.0886
data/restrains/
parameters
3436/0/236 4595/15/407 4882/0/281
absolute structure
-0.02(2)
parameter
goodness of fit on F2 1.018
1.054
1.030
a Definitions: R(Fo) ) ∑||Fo| - |Fc||/∑|Fo| and wR(Fo ) ) {∑[w(Fo
2
2
- Fc2)2]/∑[w(Fc2)2]1/2
.
1
1188, 1075 cm-1; H NMR (CDCl3) δ 1.42 (s, 12H), 4.10 (s, 4H),
7.26-7.48 (m, 4H), 7.92-7.95 (m,4H); 13C NMR (CDCl3) δ 28.97
(s), 68.86 (s), 79.26 (s), 161.75 (s), 125.88 (s), 126.79 (s), 129.59 (s),
130.85 (s), 131.48 (s), 133.91 (s); 77Se NMR (CDCl3) δ 454.7; m/z
506 (M+), 426, 299, 253 (100), 199, 181, 110, 77, 54. Anal. Calcd for
C22H24N2O2Se2: C, 52.18; H, 4.78; N, 5.53. Found: C, 52.52; H, 4.86;
N, 5.58.
(t, 1H), 7.45 (d, 1H), 7.48 (t, 1H), 7.63 (dd, 1H), 7.7 (dd, 1H), 7.86
(dd, 1H); 13C NMR (CDCl3) δ 46.59, 119.5, 125.79, 125.88, 126.24,
126.9, 128.1, 130.52, 135.98, 151.0; 77Se NMR (CDCl3) δ 485.2, 648.6;
m/z 498 (M+), 494 (M+ - 4), 294 (100), 234, 219, 170, 155, 140.
Anal. Calcd for C24H24N2Se2: C, 57.84; H, 4.85; N, 5.62. Found: C,
57.62; H, 4.63; N, 5.85.
Synthesis of bis[2-(4-ethyl-2-oxazolinyl)phenyl]diselenide (21): A
stirred solution of 4-R-(-)-ethyl-2-phenyloxazoline (1.78 g, 10.16
mmol) in dry ether (75 mL) was treated dropwise with a 1.6 M solution
of n-BuLi in hexane (6.88 mL, 11.01 mmol) via syringe under N2 at 0
°C. On stirring the reaction mixture for 5 h at this temperature the
lithiated product was obtained. Selenium powder (0.79 g, 10.01 mmol)
was added to the solution under a brisk flow of N2 gas and stirring
was continued for an additional 2 h at 0 °C. The reaction mixture was
then removed from the N2 line and poured into a beaker containing
cold aqueous NaHCO3 and O2 was passed at a moderate rate for 15
min. The organic phase was separated, dried over Na2SO4, and filtered.
The filtrate was evaporated to dryness to give a yellow oil. The
crystalline solid of the desired compound was obtained upon cooling.
The compound was recrystallized from the chloroform/methanol
mixture to give pale yellow crystals. Yield 1.03 g (40%); mp 120-
Synthesis of 2-[4,4-dimethyl-2-oxazolinyl]phenyl selenol (34):
Sodium borohydride (0.08 g, 0.2 mmol) was added to a solution of 20
(50.63 mg, 0.1 mmol) in 1 mL of methanol, and the mixture was
allowed to stand for 1 h with occasional shaking. To this was added
CDCl3 (2 mL) and the 77Se NMR spectrum of the sample was obtained,
showing a resonance at 17.9 ppm, attributed to the borane complex of
34. The addition of dilute HCl produced a new doublet centered at 9.9
ppm assigned to the air-sensitive selenol, 34, which was not further
characterized. (JSe-H ) 20.3 Hz).
Synthesis of [2-(4,4-dimethyl-2-oxazolinyl)phenyl]selenenylphenyl
sulfide (35): The diselenide (20, 0.51 g, 1.01 mmol) was dissolved in
CH2Cl2 under air and benzenethiol (0.21 mL, 2.02 mmol) was added
to the solution. After 2 h of stirring under air, the reaction mixture
was concentrated under reduced pressure. Addition of hexane afforded
a white solid that was filtered and dried under nitrogen to give pure
35. Yield 0.67 g (92%); IR (KBr) 3062, 2965, 2891, 1657, 1560, 1466,
122 °C; IR (KBr) 2962, 1645, 1464, 1430, 1359, 1135, 1069 cm-1; .
1
[R]23 113.9 (c 1, CHCl3); H NMR (CDCl3) δ 1.10 (t, 6H), 1.68 (m,
1
D
1361, 1282, 1188, 1040 cm-1; H NMR (CDCl3) δ 1.44 (s, 6H), 4.14
4H), 4.08 (t, 2H), 4.40 (m, 2H), 4.44 (t, 2H), 7.19-7.27 (m, 4H), 7.79-
7.68 (m, 4H); 13C NMR (CDCl3) δ 10.54 (s), 29.16 (s), 68.53 (s), 72.24
(s), 125.64 (s), 126.13 (s), 129.53 (s), 130.52 (s), 131.36 (s), 133.52
(s), 162.98 (s); 77Se NMR (CDCl3) δ 456.56; m/z 506 (M+), 427, 253
(100), 199, 181, 103, 70, 54. Anal. Calcd for C22H24N2O2Se2: C, 52.18;
H, 4.78; N, 5.53. Found: C, 51.92; H, 4.84; N, 5.25
(s, 2H), 7.10-7.30 (m, 4H), 7.37-7.42 (t, 1H), 7.46-7.50 (d, 2H),
7.80-7.82 (d, 1H), 8.14-8.17 (d, 1H); 13C NMR (CDCl3) δ 161.90,
137.04, 137.01, 131.36, 129.21, 128.86, 127.57, 126.21, 125.76, 125.38,
79.49, 68.46, 28.76; 77Se NMR (CDCl3) δ 576.7; m/z (FAB) 364 (M+),
254 (100%), 199, 182, 154, 136. Anal. Calcd for C17H17NOSSe: C,
56.35; H, 4.73; N, 3.87. Found: C, 56.30; H, 4.72; N, 3.79.
Synthesis of bis[8-(dimethylamino)-1-naphthyl]diselenide (22):
A stirred solution of 1-dimethylaminonaphthalene (1.04 g, 6.07 mmol)
in dry ether (50 mL) was treated dropwise with a 1.6 M solution of
n-BuLi in hexane (4.06 mL, 6.50 mmol) via syringe under N2 at room
temperature. The mixture was stirred for 24 h, during which a yellow
precipitate of 8-(dimethylamino)-1-naphthyllithium etherate was slowly
formed. To this suspension elemental selenium (0.48 g., 6.08 mmol)
was added rapidly. After 3 h all the selenium was consumed to produce
a yellow solution of lithium naphthylselenolate. This was poured into
a beaker containing aqueous NaHCO3. The resulting organic layer and
ethyl acetate extract from the aqueous layer were combined, dried over
Na2SO4, and concentrated under vacuuo to give a yellow powder.
Recrystallization of this from pentane gave yellow crystals. Yield 0.91
g (60%); mp 136-138 °C dec; IR (KBr) 3061, 2979, 2935, 1560, 1447,
1357, 1290, 1207, 1025 cm-1; 1H NMR (CDCl3) δ 2.85 (s, 12H), 7.21
Kinetic Analysis. The reactions of model compounds with ben-
zenethiol (PhSH) and H2O2 were studied in methanol by following the
appearance of the disulfide absorption at 305 nm, at 25 °C. Each initial
velocity was measured at least 6 times and calculated from the first
5-10% of the reaction. For the peroxidase activity, the rates were
corrected for the background reaction between H2O2 and PhSH. The
actual concentration of PhSH in the kinetic apparatus was measured
from the 305 nm absorbance, and rates were corrected for any variation
in the concentration of PhSH. The molar extinction coefficient of
PhSSPh (ꢀ1 ) 1.24 × 103 M-1 cm-1) at the wavelength was much
larger than that of PhSH (ꢀ2 ) 9 M-1 cm-1).7b The concentration of
PhSH (C) was therefore calculated from the absorbance (a) according
to the following equation: C ) (ꢀ1C0 - 2a)/(ꢀ1 - 2ꢀ2) ≈ C0 - 2a/ꢀ1.
The initial reduction rate of H2O2 (V0) was then determined by 1/V vs
1/[PhSH] plots using the Grapher program. The concentration of the