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4.1.1. Butyl o-diethynylbenzene sulfide 2. A solution of 1
(382 mg, 1.35 mmol) in ether (30 mL) was cooled to
278 8C. BuLi (1.6 M in hexanes, 9.50 mL, 15.2 mmol)
was added dropwise and allowed to stir for 1 h. A solution of
SCl2 (0.440 mL, 6.93 mmol) in ether (10 mL) cooled to 0 8C
was added dropwise via cannula. The mixture was allowed
to stir for 1 h and then warmed over 2 h. Quenching with
water (75 mL) was followed by extraction with hexanes
(3£50 mL). The organic layers were combined, washed
with brine (2£150 mL), and dried over anhydrous Na2SO4.
Flash chromatography on silica gel (hexanes) yielded 2 with
the triple bond protected as the ethynyl triisopropylsilyl
group (241 mg of a pale yellow oil, 48%). 1H NMR
(400 MHz, CDCl3) d 7.47–7.43 (m, 1H), 7.41–7.37 (m,
1H), 7.25–7.17 (m, 2H), 2.82 (t, J¼7.3 Hz, 2H), 1.78 (tt,
J¼7.4, 7.4 Hz, 2H), 1.48 (qt, J¼7.4, 7.3 Hz, 2H), 1.16 (s,
21H), 0.96 (t, J¼7.4 Hz, 3H); 13C NMR (100 MHz, CDCl3)
d 132.62, 131.85, 127.93, 127.38, 126.37, 125.53, 105.33,
94.85, 91.59, 84.19, 35.59, 31.39, 21.38, 18.64, 13.51,
11.26; GC–MS (EI) m/z (% relative intensity) 370 (42,
Mþ), 327 (100), 303 (8), 285 (10), 271 (8), 257 (16), 247
(19), 229 (41), 219 (28), 201 (52), 195 (28), 181 (33), 167
(14), 141 (14); IR (film) 3060, 2958, 2941, 2891, 2864,
2160, 1475, 1464, 1440, 1382, 1365, 1272, 1232, 1203,
1159, 1099, 1072, 1016, 995, 946, 918, 883, 814, 756, 677,
665, 636 cm21. Anal. Calcd for C23H34SSi: C, 74.53; H,
9.35. Found: C, 74.11; H, 9.11.
d 7.48–7.46 (m, 2H), 7.29–7.23 (m, 2H), 1.16 (s, 21H),
0.20 (s, 9H); 13C NMR (100 MHz, CDCl3) d 132.45,
132.38, 128.60, 127.96, 126.47, 125.10, 104.69, 103.24,
95.75, 93.82, 86.03, 75.34, 18.64, 11.22, 20.46; GC–MS
(EI) m/z (% relative intensity) 410 (1.3, Mþ) 367 (34), 325
(75), 299 (50), 283 (100), 251 (61), 235 (85), 223 (41), 219
(31), 209 (31), 195 (36), 191 (15), 165 (13), 149 (7), 115 (6);
IR (film) 3063, 2958, 2943, 2891, 2866, 2160, 2104, 1475,
1464, 1441, 1383, 1365, 1252, 1234, 1203, 1159, 1099,
1072, 1037, 1016, 995, 949, 920, 871, 845, 812, 758, 700,
677, 665, 635 cm21. Anal. Calcd for C24H34SSi2: C, 70.18;
H, 8.34. Found: C, 69.92; H, 8.21.
4.1.3. o-Diethynylbenzene ethynyl sulfide 5. The com-
pound was more conveniently prepared by the same method
as 4 without isolation of the deprotected intermediates; 1
(609 mg, 2.16 mmol), trimethylsilylacetylene (2.62 mL,
18.9 mmol), BuLi (2.5 M in hexanes, 8.50 mL,
21.3 mmol), and SCl2 (0.675 mL, 10.6 mmol). After
removal of the trimethylsilyl group by stirring in ether
(2.5 mL) and MeOH (2.5 mL) with K2CO3 (6 mg) until
starting material was consumed as indicated by TLC
analysis, the crude material was poured into water
(10 mL) and extracted with hexanes (3£10 mL). The
organic layers were combined, washed with brine
(2£10 mL), and dried over anhydrous Na2SO4. The solvent
and diethynylsulfide byproduct were removed by rotary
evaporation. The triisopropylsilyl group was removed by
dissolution of the crude material in THF (5 mL) and stirring
with TBAF (8.4 mL, 8.4 mmol) and EtOH (0.20 mL) until
all starting material was consumed as indicated by TLC
analysis. The mixture was added to water (20 mL) and
extracted with hexanes (3£20 mL). The organic layers were
combined, and washed with brine (2£60 mL), and dried
over anhydrous Na2SO4. Flash chromatography on silica gel
(9:1, hexanes/CH2Cl2) yielded 5 (103 mg, 26%) as an
Removal of the TIPS group from the above sulfide (153 mg,
0.411 mmol) was achieved by stirring in THF (2.5 mL) with
TBAF (1.0 M in THF, 0.81 mL, 0.81 mmol) and EtOH
(0.05 mL) until starting material was consumed as indicated
by TLC analysis. The mixture was added to water (10 mL)
and extracted with hexanes (3£10 mL). The organic layers
were combined, washed with brine (2£30 mL), and dried
over anhydrous Na2SO4. Flash chromatography (9:1,
hexanes/CH2Cl2), yielded 2 as a pale yellow oil (88.2 mg,
1
unstable yellow oil. H NMR (500 MHz, CDCl3) d 7.54–
1
87%). H NMR (500 MHz, CDCl3) d 7.49–7.46 (m, 1H),
7.44 (m, 2H), 7.35–7.27 (m, 2H), 3.33 (s, 1H), 3.02 (s, 1H);
13C NMR (125 MHz, CDCl3) d 132.55, 131.93, 128.64,
128.49, 124.98, 124.71, 93.72, 84.13, 81.57, 81.46, 75.04,
67.50; IR (film) 3288, 3063, 2177, 2108, 2054, 1963, 1917,
7.40–7.37 (m, 1H), 7.29–7.25 (m, 1H), 7.24–7.20 (m, 1H),
3.27 (s, 1H), 2.83 (t, J¼7.3 Hz, 2H), 1.85 (tt, J¼7.4, 7.4 Hz,
2H), 1.49 (qt, J¼7.5, 7.4 Hz, 2H) 0.96 (t, J¼7.3 Hz, 3H);
13C NMR (100 MHz, CDCl3) d 132.58, 131.20, 128.53,
127.32, 126.73, 123.86, 91.55, 84.71, 80.72, 80.69, 35.63,
31.29, 21.38, 15.53; GC–MS (EI) m/z (% relative intensity)
214 (51, Mþ), 184 (9), 158 (100), 114 (33); IR (film) 3300,
3286, 3061, 2958, 2929, 2872, 2168, 2108, 1475, 1438,
1379, 1255, 1225, 1159, 1095, 1036, 935, 916, 874, 756,
650 cm21. HRMS-EI (m/z): Mþ calcd for C14H14S,
214.0816; found, 214.0822.
1475, 1441, 1095, 1036, 953, 876, 758, 690, 656, 625 cm21
.
HRMS-EI (m/z): Mþ calcd for C12H6S, 182.0190; found,
182.0194.
4.1.4. Tetrayne 6. A solution of 1 (952.2 mg, 3.37 mmol) in
ether (50 mL) was cooled to 278 8C. BuLi (1.6 M in
hexanes, 2.10 mL, 3.36 mmol) was added dropwise and the
reaction mixture allowed to stir for 2 h. A solution of SCl2
(0.110 mL, 1.73 mmol) in ether (10 mL) cooled to 0 8C was
added dropwise via cannula. The mixture was allowed to stir
for 1 h and then warmed over 2 h. Quenching with water
(100 mL) was followed by extraction with hexanes
(3£100 mL). The organic layers were combined, washed
with brine (2£150 mL), and dried over anhydrous Na2SO4.
Flash chromatography on silica gel (9:1, hexanes/CH2Cl2)
4.1.2. Triyne 4. A solution of 1 (694.1 mg, 2.46 mmol) in
ether (80 mL) was cooled to 278 8C. BuLi (2.5 M in
hexanes, 9.65 mL, 24.1 mmol) was added dropwise fol-
lowed by slow addition of trimethylsilylacetylene (3.10 mL,
22.4 mmol). After stirring 2 h, a solution of SCl2 (0.770 mL,
12.1 mmol) in ether (30 mL) cooled to 0 8C was added
dropwise via cannula. The mixture was allowed to stir for
2 h and then warmed over 2 h. Quenching with water
(150 mL) was followed by extraction with hexanes
(3£100 mL). The organic layers were combined, washed
with brine (2£150 mL), and dried over anhydrous Na2SO4.
Flash chromatography on silica gel (hexanes) yielded 4
(567 mg, 56%) as a yellow oil. 1H NMR (500 MHz, CDCl3)
1
yielded 6 (731 mg, 73%) as a viscous yellow oil. H NMR
(500 MHz, CDCl3) d 7.50–7.44 (m, 4H), 7.26 (td, J¼7.5,
2.1 Hz, 4H), 1.15 (s, 42H); 13C NMR (100 MHz, CDCl3) d
132.38, 132.06, 128.37, 127.87, 126.20, 125.10, 104.65,
95.68, 93.40, 75.82, 18.68, 11.31; MS (EI, 70 eV) m/z (%
relative intensity) 594 (35, Mþ) 551 (17), 509 (34), 467 (27),
425 (21), 321 (14), 239 (26), 157 (67), 115 (100); IR (film)