5062 J. Am. Chem. Soc., Vol. 122, No. 21, 2000
Block et al.
1H); 13C NMR δ 126.39, 121.70, 120.30, 119.11; CI LC-MS m/z 133
(M+ + 1); IR (νmax, neat) 1593 (m), 1515 (m), 1319 (m), 1074 (s;
(benzylthio)-1,3-butadiene S-oxide, was prepared and showed 1H NMR
δ 6.98 (dd, 3J ) 9.5, 4.7 Hz, S(O)CHdCH, 1H); 7.03-7.08 (m, SCHd
3
5
SdO) cm-1
.
CH, 2H); 7.18 (dd, J ) 9.5 Hz, J ) 1.1 Hz, S(O)CHdCH, 1H).
Sodium thiosulfate (0.7 mL, 1 M) in MeOH (10 mL) reduction of 9
(1.1 mmol) for 16 h gave 6c (292 mg, yield 77%), off-white needles,
mp 120-121 °C. 1H NMR δ 3.89 (s, 2H, SCH2Ph), 3.92 (s, 2H, SeCH2-
Ph), 6.05 (d, 1H, 3J ) 9.6 Hz, SCH)CH), 6.17 (dd, 1H, 3J ) 10.3, 9.6
1,2-Dithiin 1,1-Dioxide (38c). To a solution of 1c (58 mg, 0.5 mmol)
in CH2Cl2 (15 mL) was added mCPBA (450 mg, 57-86%) in CH2Cl2
(30 mL) at 0 °C. The mixture was stirred overnight at 25 °C,
concentrated, and chromatographed (5:2 hexane-EtOAc) giving 38c
3
1
3
Hz, SCHdCH), 6.40 (d, 1H, J ) 9.4 Hz, SeCHdCH), 6.64 (dd, 1H,
as a light brown oil (33 mg, 44% yield); H NMR δ 7.14 (H6, dd, J
3J ) 10.3, 9.4 Hz, SeCHdCH), 7.2-7.3 (m, 10H); 13C NMR δ 30.08
(SCH2Ph), 38.09 (SeCH2Ph), 124.56 (SCHdCH), 126.80 (SeCHdCH),
127.68 (SCHdCH), 128.31 (SeCHdCH), 128.58, 128.78, 128.84 (Ph);
77Se NMR δ 312; MS (70 eV) m/z 346 (M+). Anal. Calcd for C18H18-
SSe: C, 62.42; H, 5.24. Found: C 61.95, H 5.37.
3
) 9.9, 1.0 Hz, 1H), 6.94 (H4, dd, J ) 10.5, 6.5 Hz, 1H), 6.83 (H3,
dd, J ) 10.5, 1.0 Hz, 1H), 6.76 (H5, dd, J ) 9.9, 6.5 Hz, 1H); 13C
NMR δ 134.56, 128.79, 126.81, 121.54; IR (νmax, neat) 3056 (m), 1590
(m), 1534 (m), 1326 (s; SO2), 1127 (s; SO2) cm-1; UV-vis (CH3CN)
λmax 316 nm.
3
3
2-Selenathiin (5c). The synthesis of 5a was followed, using sodium.
Yield of 5c, 56% (orange solution; by NMR, 1,4-dioxane standard);
1H NMR δ 6.00 (dd, 3Jcis ) 7.9 Hz, 5J ) 1.7 Hz, 1H), 6.26-6.29 (m,
3H); 13C NMR δ 113.76 (SeCHdCH), 119.25 (SCHdCH), 129.67
(SCHdCH), 131.97 (SeCHdCH); 77Se NMR δ 228; UV-vis (hexane)
λmax ) 488 nm; GC-MS (70 eV) m/z 164 (M+, 20%), 84 (100%), 58
(100%).
(Z,Z)-1,4-Bis(benzylseleno)-1,3-butadiene (6b). A suspension of
dibenzyl diselenide (2.0 g, 5.9 mmol) in EtOH (25 mL) at 0 °C was
treated with NaBH4 (0.88 g, 23.6 mmol) in small portions, 1,4-bis-
(trimethylsilyl)-1,3-butadiene (1b; 0.57 g, 2.94 mmol) was added, and
the mixture was refluxed for 4 h, cooled to 0 °C, and filtered. The
precipitate was dissolved in CH2Cl2, filtered, concentrated, washed with
EtOH, and dried, giving 6b (0.92 g, 80%), as off-white plates; mp 124-
1
3
5
2-Selenathiin 2-Oxide (39c). Due to the instability of the title
compound, the following manipulations were conducted at -50 to -20
°C. The synthesis of 39a was followed using a solution of 5c (2.6 mg,
0.02 mmol) in CD2Cl2, 1,4-dioxane as internal standard, and a slight
excess of mCPBA; 1H NMR (CD2Cl2) δ 6.81 (d, 3J ) 8.4 Hz, SCHd
125 °C; H NMR δ ) 3.92 (s, 4H), 6.44 (dd, 2H, Jcis ) 7 Hz, J )
3
5
1.9 Hz), 6.52 (dd, Jcis ) 7 Hz, J ) 1.9 Hz, 2H), 7.2 (m, 10H); 13C
NMR δ 30.15, 124.16, 127.01, 128.41, 128.59, 128.85, 138.44; 77Se
NMR δ 315; MS (70 eV) m/z 394 (M+). Anal. Calcd for C18H18Se2:
C, 54.83; H 4.60. Found: C, 54.30; H, 4.75.
3
3
CH, 1H); 7.01 (dd, J ) 8.4, 9.6 Hz, SCHdCH, 1H); 7.22 (d, J ) 9
Hz, Se(O)CHdCH, 1H); 7.36 (dd, 3J ) 9, 9.6 Hz, Se(O)CHdCH, 1H).
1,4-Bis(benzylthio)-1,3-butadiyne (15). Benzylthioethyne (8 g, 60
mmol) was slowly added to a stirred solution of CuCl (0.27 g) and
TMEDA (0.41 mL) in acetone (40 mL) at 25 °C into which oxygen
was bubbled. After 3 h, the mixture was concentrated and treated with
dilute ice cold HCl solution (0.3 mL concentrated HCl diluted to 50
mL). The suspension was extracted with ether (2 × 50 mL), the
combined ether layers were washed with brine (2 × 50 mL) and water
(35 mL), dried, and concentrated in vacuo affording 15 as a yellow
solid (7.7 g, 97%) of good purity. An analytical sample of 15 prepared
by flash chromatography (1:9 CH2Cl2-hexanes) had mp 38-39 °C;
1H NMR δ 7.4-7.2 (m, 10H), 3.96 (s, 4H); 13C NMR δ 135.99, 129.07,
128.79, 128.05, 82.43, 74.22, 40.98; GC-EI-MS m/z 294 (M+); IR
(νmax, neat) 2075 cm-1 (CtC). Anal. Calcd for C18H14S2: C, 73.43;
H, 4.79. Found: C, 73.46; H, 4.86.
1,2-Diselenin (5a). To liquid NH3 (70 mL) in a 100 mL three-necked
flask at -78 °C was added 6b (0.98 g, 2.8 mmol) followed by lithium
(0.2 g, 28 mmol) in small pieces. The blue solution was stirred for 1.5
h at -60 °C, quenched (MeOH), and evaporated. Under argon the
residue was dissolved in degassed aqueous 10% KOH solution (150
mL) which was extracted with degassed hexane (3 × 20 mL) to remove
toluene. The aqueous solution was then covered with hexane (70 mL),
oxygen was carefully bubbled through the solution until the hexane
phase turned red. The extraction process was repeated twice with fresh
hexane (2 × 70 mL). After drying the hexane extract, hexadecane (15
mL) was added, hexane was evaporated (water pump vacuum, 15 °C),
CDCl3 (2 mL) was added, and the volatiles were transferred at 0.02
Torr to a liquid nitrogen cooled “flash distillation” trap.8b Yield of 5a,
68% (deep red solution; by NMR with 1,4-dioxane standard); 1H NMR
δ 6.10 (m, 2H, H3,6), 6.27 (m, 2H, H4,5, AA′BB′ multiplets with 3J3,4/5,6
4
3
5
) 9.1, J3,5/6,4 ) 0, J4,5 ) 5.1, J3,6 ) 1.9 Hz); 13C NMR δ 112.78
(C3,6), 132.22 (C4,5); 77Se NMR δ 119 (vs Me2Se); UV-vis (hexane)
λmax ) 504 (ꢀ 107), 312 (ꢀ 1294), 234 (ꢀ 1189), 214 (ꢀ 1076) nm;
GC-MS (70 eV) m/z 212 (M+; 57%), 132 (100%).
(E,E)-1,4-Bis(benzylthio)-1,4-bis(triphenylstannyl)-1,3-butadi-
ene (16). Tetrakis(triphenylphosphine)palladium(0) (0.20 g, 0.17 mmol)
was added to a stirred solution of 15 (1.47 g, 5 mmol) in hexane-
CH2Cl2 (600 mL, 4:1). Triphenyltin hydride (4.38 g, 12.5 mmol) was
added dropwise to the solution at -50 °C. After 10 min, the mixture
was slowly allowed to warm. A precipitate appeared at -30 to -20
°C and was collected at 25 °C, giving 16 as a yellow solid (1.74 g,
1,2-Diselenin 1-Oxide (39a). Due to the instability of the title
compound, the following manipulations were conducted at -50 to -20
°C. A solution of 5a ( ∼3 mg) in CD2Cl2 (0.7 mL) and 1,4-dioxane as
internal standard (4.7 mg) were added to an NMR tube, cooled to -50
°C, treated with mCPBA ( ∼4 mg), and shaken to achieve homogeneity;
1
35%), mp 157-159 °C; H NMR δ 7.7-6.8 (m, 42H), 3.68 (s, 4H);
13C NMR δ 141-136 (several), 129.5-126 (several), 40.54. Anal.
Calcd for C54H46S2Sn2: C, 65.10; H, 4.62. Found: C, 65.08; H, 4.77.
The structure of 16 was determined by X-ray crystallography.6
(E,E)-1,4-Bis(benzylthio)-1,4-diiodo-1,3-butadiene (17). Iodine
(122 mg, 0.48 mmol) in CH2Cl2 (3 mL) was added during 1.5 h at 0
°C to a stirred solution of 16 (200 mg, 0.20 mmol) in CH2Cl2 (9 mL)
using a syringe pump. The solution was stirred overnight at 25 °C and
then washed (NaHSO3 [2 × 20 mL] and KF [20 mL]), dried, filtered,
concentrated, and chromatographed (1:6 CH2Cl2-hexanes) giving 17
as a pale yellow solid (110 mg, 100% yield) with mp 111-112 °C; 1H
NMR δ 7.35-7.20 (m, 10H), 7.17 (s, 2H), 3.85 (s, 4H); 13C NMR δ
145.25, 136.36, 129.18, 128.63, 127.69, 95.10, 42.77. Anal. Calcd for
C18H16S2I2: C, 39.29; H, 2.93. Found: C, 39.50; H, 3.13.
3
5
1H NMR (CD2Cl2, -38 °C) δ 6.87 (dd, J ) 10.2 Hz, J ) 0.9 Hz,
3
SeCHdCH, 1H); 6.95 (dd, J ) 10.2, 7.2 Hz, SeCHdCH, 1H); 7.11
(dd, 3J ) 10.2, 7.2 Hz, Se(O)CHdCH, 1H); 7.24 (dd, 3J ) 10.2 Hz, 5J
) 0.9 Hz, Se(O)CHdCH, 1H).
(Z,Z)-1-Benzylseleno-4-benzylthio-1,3-butadiene (6c). As for 6b,
BnSeNa (from 8.55 g, 25 mmol BnSeSeBn) and BnSNa (from 6.2 g,
50 mmol R-toluenethiol and 150 mmol NaOMe in 120 mL MeOH)
were refluxed with 1,4-bis(trimethylsilyl)-1,3-butadiene (7.0 g, 36
mmol) for 24 h. A precipitate containing 1:1:2 6a:6b:6c (10.8 g) formed
at 0 °C. Oxidation of 1.22 g of this solid in THF (11 mL) with 30%
H2O2 (0.6 mL) at 25 °C for 2 h precipitated (Z,Z)-1,4-bis(benzylseleno)-
1,3-butadiene Se,Se-bis-oxide 10 (0.33 g), 77Se NMR (δ 878) and IR
1
3
5
(νmax, neat) 785 cm-1 (SedO); H NMR δ 6.87 (dd, J ) 10.2 Hz, J
3
) 0.9 Hz, SeCHdCH, 1H); 6.95 (dd, J ) 10.2, 7.2 Hz, SeCHdCH,
(E,E)-2,4-Bis(benzylthio)-2,4-hexadiene (18). Methyllithium in
ether (1.5 M, 1.33 mL, 2 mmol) was added to a stirred suspension of
Cu2I2 (0.190 g) in ether (1 mL) at -15 °C. The solution was cooled to
-78 °C, 17 (55 mg, 0.1 mmol) in ether was added, and stirring was
continued for 1 h at -78 °C. At 25 °C, the solution was quenched
with NH4Cl solution (2.5 mL) and extracted with ether, and the ether
layers were washed with brine and water and were dried, filtered,
concentrated, and chromatographed (1:9 CH2Cl2-hexanes) to afford
18 as a yellow solid (20.5 mg, 63% yield); 1H NMR δ 7.29 (m, 10H),
1H); 7.11 (dd, 3J ) 10.2, 7.24 Hz, Se(O)CHdCH, 1H); 7.24 (dd, 3J )
5
10.2 Hz, J ) 0.9 Hz, Se(O)CHdCH, 1H). Chromatography of the
filtrate (silica gel; CH2Cl2:MeOH 19:1) gave solid (Z,Z)-1-benzylseleno-
4-benzylthio-1,3-butadiene Se-oxide 9, 400 mg, yield 61%); 77Se NMR,
δ 867; IR (νmax, neat) 802 cm-1; H NMR δ 6.81 (d, J ) 8.4 Hz,
1
3
3
SCHdCH, 1H); 7.01 (dd, J ) 8.4, 9.6 Hz, SCHdCH, 1H); 7.22 (d,
3J ) 9 Hz, Se(O)CHdCH, 1H); 7.36 (dd, 3J ) 9, 9.6 Hz, Se(O)CHd
CH, 1H). For comparison the monosulfoxide of 6a, (Z,Z)-1,4-bis-