Interactions Between Divalent Selenium Centers
a yellow oil. MS (EI): m/z (%) = 280 (42.5) [M]+, 265 (62.1) [M –
CH3]+, 250 (40.6) [M – 2CH3]+, 185 (37.4) [M – SeCH3]+, 169
2-Bromobenzyl tert-Butyldimethylsilyl Ether (6): A solution of
TBSCl (5.6 g, 37 mmol) in dry DMF (10 mL) was added by using
a syringe to a solution of 2-bromobenzyl alcohol (5; 5.8 g,
31.0 mmol) and imidazole (5.2 g, 76.4 mmol) in dry DMF (50 mL)
(53.9) [C7H7Se]+, 105 (100) [C8H9]+, 91 (43.8) [C7H7]+, 78 (11.5)
2
[C6H5]+. 1H NMR (500 MHz, CD2Cl2): δ = 1.93 (s, JSe,H
=
2
10.6 Hz, 3 H, CH2SeCH3), 2.32 (s, JSe,H = 11.8 Hz, 3 H, CH3), in a 250 mL Schlenk flask. The reaction mixture was stirred at
2
3.87 (s, JSe,H = 12.6 Hz, 2 H, CH2), 7.13–7.18 (m, 3 H, Harom) [at
low temperature it separated into three signals: δ = 7.25 (ddd, J =
7.8, 7.5, 1.5 Hz, 1 H), 7.16 (ddd, J = 7.8, 7.6, 1.2 Hz, 1 H), 7.09
room temperature for 20 h. The reaction was quenched with deion-
ized water (100 mL) and extracted with diethyl ether (4ϫ70 mL).
The combined organic layers were washed with water and brine
and then dried with MgSO4. The solvent was evaporated to afford
a brown oil as raw product. A yield of 8.6 g of 6 (92%) was isolated
by purification using column chromatography on silica gel, eluting
(dd, J = 7.5, 1.2 Hz, 1 H)], 7.41 (dd, J = 7.6, 1.5 Hz 1 H, Harom
)
1
ppm. 13C NMR (125MHz, CD2Cl2): δ = 4.6 (p-CH2SeCH3, JSe,C
1
1
= 64.6 Hz), 7.6 (p-SeCH3, JSe,C = 65.1 Hz), 28.9 (s-CH2Se, JSe,C
3
= 57.9, JSe,C = 13.0 Hz), 126.2 (t-Carom), 127.8 (t-Carom), 129.8 with petroleum ether/dichloromethane (10:1). MS (EI): m/z (%) =
(t-Carom), 131.0 (t-Carom), 133.4 (q-Carom, C-Se), 140.1 (q-Carom, C-
CH2) ppm. 77Se NMR (95 MHz, CD2Cl2): δ = 158.9 (4JSe,Se
37.8 Hz, SeCH3), 161.0 (4JSe,Se = 37.8 Hz, CH2SeCH3) ppm. IR
301 (ca. 1) [M]+, 243 (100) [M – C4H9]+, 213 (27.2) [M – C6H15]+,
169 (46.9) [M – C6H15OSi]+, 105 (5.2) [C7H6O]+, 90 (3.5) [C7H6]+.
1H NMR (300 MHz, CDCl3): δ = 0.15 [s, 6 H, Si(CH3)2], 0.99 [s,
9 H, SiC(CH3)3], 4.76 (s, 2 H, CH2), 7.12 (td, J = 7.8, 0.5 Hz, 1 H,
=
(film): ν = 3055 (w), 3001 (m), 2923 (s), 2072 (w), 1948 (w), 1692
˜
(w), 1583 (m), 1463 (s), 1438 (s), 1424 (s), 1270 (m), 1031 (m), 904
Harom), 7.34 (td, J = 7.8, 0.6 Hz, 1 H, Harom), 7.50 (dd, J = 7.9,
(m), 754 (vs) cm–1. HRMS (positive EI): calcd. for
0.5 Hz, 1 H, Harom), 7.58 (dd, J = 7.8, 0.6 Hz, 1 H, Harom) ppm.
13C NMR (75 MHz, CDCl3): δ = –5.3 [2 C, p-Si(CH3)2], 18.4 [q-
SiC(CH3)3], 25.9 [3 C, p-SiC(CH3)3], 64.6 (s-CH2), 121.0 (q-
CaromBr), 127.3 (t-Carom), 127.5 (t-Carom), 128.1 (t-Carom), 132.0 (t-
1
12C9 H1278Se82Se [M]+ 279.9269; found 279.9287 (+0.8 mmu).
Methyl 3-(Methylselenyl)benzyl Selenide (14): Starting materials: 3-
bromobenzyl bromide (4b; 5.0 g, 20 mmol), freshly prepared lith-
ium methaneselenolate (10.1 g, 100 mmol, in 200 mL THF/diethyl
ether solution), and methyl iodide (6.25 mL, 100 mmol). Reaction
time: 66 h. Column chromatography on silica gel by using light
petroleum/diethyl ether (10:1) afforded 0.7 g (13%) of pure 14 as a
yellow oil. MS (EI): m/z (%) = 280 (24.2) [M]+, 265 (0.5) [M –
CH3]+, 249 (0.9) [M – 2CH3]+, 185 (100) [M – SeCH3]+, 170 (31.3)
[C7H7Se]+, 104 (32.5) [C8H9]+, 95 (7) [CH3Se]+, 91 (8.9) [C7H7]+,
Carom), 140.3 (q-CaromCH ) ppm. IR (KBr): ν = 3500–3150 (br. s),
˜
2
2955 (s), 2930 (s), 2885 (m), 2857 (s), 1700 (m), 1471 (m), 1442 (m),
1291 (s), 1255 (m), 1201 (m), 1130 (m), 1098 (m), 1044 (m), 1027
(m) cm–1.
tert-Butyldimethylsilyl 2-(Methylselenyl)benzyl Ether (7): A solution
of lithium methaneselenolate (6.0 g, 60 mmol) in THF/diethyl ether
solution (100 mL, prepared as described above) was added to a
solution of 6 (6.03 g, 20 mmol) in dry DMF (100 mL). The reaction
1
2
78 (5.9) [C6H5]+. H NMR (500 MHz, CD2Cl2): δ = 1.91 (s, JSe,H
2
= 10.6 Hz, 3 H, CH3), 2.34 (s, JSe,H = 11.2 Hz, 3 H, CH3), 3.69 mixture was heated to 70 °C to remove the THF and diethyl ether
(s, JSe,H = 13.3 Hz, 2 H, CH2), 7.094 (dt, J = 7.6, 1.3 Hz, 1 H,
2
by distillation. Subsequently, the reaction solution was heated at
Harom), 7.18 (t, J = 7.6 Hz, 1 H, Harom), 7.25 (dt, J = 7.6, 1.3 Hz, 80–90 °C under vigorous stirring for a further 60 h. After cooling
1 H, Harom), 7.31 (t, J = 1.3 Hz, 1 H, Harom) ppm. 13C NMR to room temperature, the alkylating agent MeI (3.8 mL, 60 mmol)
(125 MHz, CD2Cl2): δ = 4.4 (p-CH2SeCH3), 7.1 (p-SeCH3), 28.2 was added and stirring continued for 45 min. Then the reaction
(s-CH2Se), 126.9 (t-Carom), 128.5 (t-Carom), 129.3 (t-Carom), 130.6 was quenched with water (ca. 200 mL). After extraction with di-
(t-Carom), 132.4 (q-Carom, C-CH2), 140.9 (q-Carom, C-Se) ppm. 77Se
NMR (95 MHz, CD2Cl2): δ = 173.5 (SeCH3), 201.1 (CH2SeCH3)
ethyl ether (4ϫ100mL), the combined organic layers were washed
with water, a saturated NaHCO3 solution, and brine, and then
dried with MgSO4. After removal of the solvent, the raw product
ppm. IR (film): ν = 3049 (w), 3000 (m), 2923 (s), 2253 (w), 1598
˜
(s), 1568 (s), 1474 (s), 1423 (s), 1272 (m), 1185 (w), 1074 (m), 903 was obtained as an orange oil. A yield of 2.98 g of pure 7 (47%)
(m), 782 (s), 696 (vs) cm–1. HRMS (positive EI): calcd. for
was isolated by column chromatography on silica gel, eluting with
petroleum ether (b.p. 30–40 °C)/diethyl ether (10:1), as a dark-
yellow oil. MS (EI): m/z (%) = 316 (Ͼ1) [M]+, 259 (100) [M –
C4H9]+, 185 (50.7) [M – C6H15SiO]+, 169 (12.0) [M – C7H18SiO]+,
91 (27.2) [M – C7H18SiOSe]+, 105 (49.3) [C7H5O]+. 1H NMR
(500 MHz, CD2Cl2): δ = 0.12 [s, 6 H, Si(CH3)2], 0.95 [s, 9 H,
SiC(CH3)3], 2.30 (s, 3 H, SeCH3), 4.74 (s, 2 H, CH2), 7.19 (td, J =
7.4, 1.3 Hz, 1 H, Harom), 7.22 (td, J = 7.4, 0.5 Hz, 1 H, Harom),
7.37 (dd, J = 7.4, 1.3 Hz, 1 H, Harom), 7.42 (td, J = 7.4, 0.5 Hz, 1
H, Harom) ppm. 13C NMR (125 MHz, CD2Cl2): δ = –5.2 [2 C, p-
Si(CH3)2], 7.0 (p-SeCH3), 18.7 [q-SiC(CH3)3], 26.1 [3 C, p-
SiC(CH3)3], 65.0 (s-CH2), 126.3 (t-Carom), 127.2 (t-Carom), 128.0 (t-
Carom), 129.8 (t-Carom), 131.3 (q-CaromSeCH3), 141.5 (q-CaromCH2)
1
12C9 H1278Se80Se [M]+ 279.9277; found 279.9272 (–0.5 mmu).
Methyl 4-(Methylselenyl)benzyl Selenide (15): Starting materials: 4-
bromobenzyl bromide (4c; 2.5 g, 10 mmol), freshly prepared lith-
ium methaneselenolate (4.0 g, 40 mmol, in 80 mL THF/diethyl
ether solution), and methyl iodide (2.5 mL, 40 mmol). Reaction
time: 60 h. Column chromatography on silica gel by using light
petroleum/diethyl ether (100:1) afforded 0.58 g (21%) of pure 15 as
yellow oil. MS (EI): m/z (%) = 280 (14.5) [M]+, 265 (1.1) [M –
CH3]+, 249 (0.6) [M – 2 CH3]+, 185 (100) [M – SeCH3]+, 170 (61.6)
[C7H7Se]+, 104 (12) [C8H9]+, 95 (3.7) [CH3Se]+, 91 (4.8) [C7H7]+,
1
2
78 (15) [C6H5]+. H NMR (500 MHz, CD2Cl2): δ = 1.90 (s, JSe,H
2
= 10.6 Hz, 3 H, CH3), 2.33 (s, JSe,H = 11.1 Hz, 3 H, CH3), 3.69
(s, JSe,H = 14.4 Hz, 2 H, CH2), 7.16 (ddd, J = 8.4, 2.1, 0.9 Hz, 2
ppm. 77Se NMR (95 MHz, CD Cl ): δ = 154.5 ppm. IR (film): ν =
˜
2
2
2
3059 (w), 2954 (s), 2929 (s), 2885 (m), 2856 (s), 1467 (m), 1448 (m),
H, Harom), 7.33 (ddd, J = 8.4, 2.1 Hz, 2 H, Harom) ppm. 13C NMR
(125MHz, CD2Cl2): δ = 4.3 (1JSe,C = 64.3 Hz, p-CH2SeCH3), 7.3
(1JSe,C = 64.9 Hz, p-SeCH3), 28.1 (1JSe,C = 58.4 Hz, s-CH2Se),
129.8 (t-Carom), 130.3 (q-Carom, C-CH2), 130.6 (2JSe,C = 11.5 Hz, t-
Carom), 138.0 (q-Carom, C-Se) ppm. 77Se NMR (95 MHz, CD2Cl2):
1255 (s), 1201 (m), 1123 (m), 1093 (s), 1051 (m), 1034 (m) cm–1.
12
HRMS (positive EI): calcd. for
C
14
1H2416O28Si80Se [M]+
316.0762; found 316.0760 (–0.1 mmu).
2-(Methylselenyl)benzyl Alcohol (8): Compound 7 (5.7 g, 18 mmol)
δ = 174.8 (SeCH ), 197.3 (CH SeCH ) ppm. IR (film): ν = 3047 was added to a solution of acetic acid (103 mL), THF (34 mL),
˜
3
2
3
(w), 2999 (m), 2922 (s), 2226 (w), 1593 (w), 1489 (s), 1423 (m), 1398 and water (34 mL). The slightly pale mixture was stirred at room
(m), 1272 (m), 1070 (m), 905 (m), 826 (m) cm–1. HRMS (positive temperature for 20 h. After extraction with diethyl ether
1
EI): calcd. for 12C9 H1280Se [M]+ 279.9269; found 279.9254
(4ϫ100 mL), the combined organic layers were washed with a
(–1.6 mmu).
large quantity of water and then saturated NaHCO3 solution and
Eur. J. Org. Chem. 2009, 2765–2774
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2771