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C.A. Johnson et al. / Journal of Organometallic Chemistry 691 (2006) 413–421
5–10 h and then concentrated in vacuo. The resultant crude
material was filtered through a 2.5 cm silica plug and then
purified by column chromatography or by Chromatotron.
then trans-PtCl2(PEt3)2 (65 mg, 0.13 mmol) and CuI
(5 mg, 0.03 mmol) according to general metallacyclization
procedure. The crude product was purified by Chromato-
tron (1 mm plate, 1:2 hexanes:CH2Cl2) to yield 6 (15 mg,
13%) as a colorless powder. Recrystallization by vapor dif-
fusion with THF/hexanes afforded light yellow crystals.
4.4. Synthesis of a,x-polyyne (4)
1
A syringe pump was used to deliver a deoxygenated
solution of 2,6-diethynylpyridine [12] (80 mg, 0.63 mmol)
in THF (10 mL) over 12 h to a stirred, deoxygenated sus-
pension of diethynylarene 3 [13] (637 mg, 1.4 mmol),
Pd(PPh3)4 (35 mg, 0.03 mmol), and CuI (11 mg,
0.06 mmol) in THF (50 mL) and i-Pr2NH (50 mL) at
50 ꢁC. The reaction was stirred an additional 24 h under
N2, then the solvent was removed by rotary evaporation.
Chromatography of the residue on silica gel (1:1 hex-
anes:CH2Cl2) afforded 4 (350 mg, 74%) as a yellow, spongy
Mp: 228 ꢁC (dec). H NMR (300 MHz, CDCl3): d 7.51 (t,
J = 7.6 Hz, 1H), 7.41 (d, J = 8.0 Hz, 2H), 7.35 (d,
J = 1.8 Hz, 2H), 7.29 (d, J = 7.6 Hz, 2H), 7.12 (dd,
J = 8.0, 1.8 Hz, 2H), 2.20–2.05 (m, 12H), 1.31 (s, 18H),
1.17–1.06 (m, 18H). 13C NMR (125 MHz, CDCl3): d
151.70, 144.61, 135.24, 132.69, 131.25, 125.95, 124.62,
122.21, 121.44, 107.94, 104.09, 91.31, 90.09, 34.83, 31.16,
16.20 (pseduo-t, J = 18.7 Hz), 8.03. 31P NMR (121 MHz,
CDCl3):
d
11.13 (pseudo-t, J = 2381 Hz). UV–Vis
(CH2Cl2): kmax (e) 269 (84000), 291 (58000), 346 (18000)
nm. MS (CI pos) m/z (%): 869 (MH+, 100), 868 (M+,
61); C45H57NP2Pt (868.97). Anal. Calc. for C45H57NP2Pt:
C, 62.20, H, 6.61, N, 1.61. Found: C, 62.13, H, 6.93, N,
1.37%.
1
solid. Mp: 67–69 ꢁC. H NMR (300 MHz, CDCl3): d 7.61
(t, J = 7.8 Hz, 1H), 7.53 (d, J = 8.1 Hz, 2H), 7.50 (d,
J = 2.1 Hz, 2H), 7.43 (d, J = 7.8 Hz, 2H), 7.32 (dd,
J = 8.1, 2.1 Hz, 2H), 1.32 (s, 18H), 1.13 (s, 42H). 13C
NMR (75 MHz, CDCl3):
d 151.88, 143.86, 135.71,
132.35, 129.49, 126.12, 125.75, 125.51, 121.94, 105.59,
94.36, 91.12, 88.41, 34.68, 30.92, 18.68, 11.28. UV–Vis
(CH2Cl2): kmax (e) 240 (66000), 259 (76000), 297 (28000),
321 (29000), 333 (31000) nm. MS (CI pos) m/z (%): 754
(M+ + 2, 29), 753 (MH+, 67), 752 (M+, 100); C51H69NSi2
(752.27). Anal. Calc. for C51H69NSi2: C, 81.43, H, 9.25,
N, 1.86. Found: C, 81.21, H, 9.47, N, 1.86%.
4.7. Synthesis of trans-platinaheterobenzocyclyne (7)
Following desilylation, polyyne 5 (100 mg, 0.13 mmol)
was reacted with Me3SnNMe2 (54 mg, 0.26 mmol) and
then trans-PtCl2(PEt3)2 (65 mg, 0.13 mmol) and CuI
(5 mg, 0.03 mmol) according to general metallacyclization
procedure. The crude product was purified by Chromato-
tron (1 mm plate, 12:1 hexanes:ethyl acetate) to yield 7
1
4.5. Synthesis of a,x-polyyne (5)
(32 mg, 29%) as a pale yellow solid. Mp: 209 ꢁC (dec). H
NMR (300 MHz, CDCl3): d 9.09 (t, J = 1.8 Hz, 1H), 8.57
(d, J = 1.8 Hz, 2H), 7.40 (d, J = 8.1 Hz, 2H), 7.34 (d,
J = 2.1 Hz, 2H), 7.15 (dd, J = 8.1, 2.1 Hz, 2H), 2.12–2.06
(m, 12H), 1.32 (s, 18H), 1.16–1.06 (m, 18H). 13C NMR
(75 MHz, CDCl3): d 151.65, 149.08, 144.24, 132.18,
120.35, 125.71, 122.20, 121.82, 121.23, 116.02 (pseudo-t,
J = 14.7 Hz), 109.13, 95.49, 87.85, 34.84, 31.16, 16.37
(pseudo-t, J = 17.4 Hz), 7.95. 31P NMR (121 MHz,
A syringe pump was used to deliver a deoxygenated
solution of 3,5-diethynylpyridine [2d] (85 mg, 0.67 mmol)
in THF (10 mL) over 12 h to a stirred, deoxygenated sus-
pension of diethynylarene 3 [13] (700 mg, 1.6 mmol),
Pd(PPh3)4 (45 mg, 0.039 mmol), and CuI (15 mg,
0.078 mmol) in THF (50 mL) and i-Pr2NH (50 mL) at
50 ꢁC. The reaction was stirred an additional 24 h under
N2, then the solvent was removed by rotary evaporation.
Chromatography of the residue on silica gel with CH2Cl2
afforded 5 (276 mg, 55%) as a yellow, spongy solid. Mp:
65–67 ꢁC. 1H NMR (300 MHz, CDCl3): d 8.64 (d,
J = 2.1 Hz, 2H), 7.92 (t, J = 2.1 Hz, 1H), 7.52 (d,
J = 2.1 Hz, 2H), 7.46 (d, J = 8.4 Hz, 2H), 7.34 (dd,
J = 8.4, 2.1 Hz, 2H), 1.33 (s, 18H), 1.23 (s, 42H). 13C
CDCl3):
d
10.60 (pseudo-t, J = 2316 Hz). UV–Vis
(CH2Cl2): kmax (e) 274 (85000), 303 (35000), 315 (28000),
344 (10000), 365 (11000) nm. MS (CI pos) m/z (%): 871
(M+ + 3, 33), 870 (M+ + 2, 82), 869 (MH+, 100), 868
(M+, 72); C45H57NP2Pt (868.97).
4.8. Synthesis of heterobenzocyclyne (8)
NMR (75 MHz, CDCl3):
d 151.96, 150.64, 140.93,
131.94, 129.59, 125.63, 125.56, 122.06, 120.18, 105.47,
94.67, 92.19, 87.95, 34.74, 30.98, 18.68, 11.28. UV–Vis
(CH2Cl2): kmax (e) 241 (77000), 249 (76000), 261 (88000),
305 (42000), 330 (36000) nm. MS (CI pos) m/z (%): 755
(M+ + 3, 21), 754 (M+ + 2, 64), 753 (MH+, 100), 752
(M+, 100); C51H69NSi2 (752.27).
Polyyne 4 (100 mg, 0.13 mmol) was deprotected and re-
acted with CuCl (653 mg, 6.5 mmol), pyridine, and MeOH
as described in general alkyne homocoupling procedure.
Purification on a Chromatotron plate (1 mm, 2:1 hex-
anes:CH2Cl2) provided 8 (41 mg, 73%) as a pale yellow so-
lid. Mp: 260 ꢁC (dec). 1H NMR (300 MHz, CDCl3): d 7.58
(t, J = 8.1 Hz, 1H), 7.53–7.52 (m, 2H), 7.33–7.35 (m, 4H),
7.20 (d, J = 7.6 Hz, 2H), 1.31 (s, 18H). 13C NMR
(75 MHz, CDCl3): d 152.38, 144.63, 136.89, 129.88,
129.47, 127.42, 126.36, 123.58, 122.57, 94.95, 90.30,
81.63, 78.88, 34.86, 30.91. UV–Vis (CH2Cl2): kmax (e) 230
4.6. Synthesis of trans-platinaheterobenzocyclyne (6)
Following desilylation, polyyne 4 (100 mg, 0.13 mmol)
was reacted with Me3SnNMe2 (54 mg, 0.26 mmol) and