Organometallics
Article
5a: colorless crystals (18.8 mg, 10%). 1H NMR (400 MHz, CDCl3):
δ 3.96 (s, 1H), 3.12 (s, 1H), 2.87 (s, 1H), 2.02 (d, J = 7.6 Hz, 1H),
1.68 (d, J = 7.6 Hz, 1H) (CH), 1.41 (s, 3H) (CH3). 13C{1H} NMR
(100 MHz, CDCl3): δ 79.4 (cage C), 78.5 (cage C), 67.8 (cage C),
66.1 (cage C), 52.7, 52.6, 47.7, 35.8, 35.7, 33.9, 17.5. 11B{1H} (96
(1B), −11.9 (2B), −12.5 (4B). HRMS (EI): calcd for
+
C11H24Si11B810B2 292.2652, found 292.2653. Anal. Calcd for
C11H24SiB10: C, 45.17; H, 8.27. Found: C, 45.10; H, 8.03. 4c′:
colorless crystals. 1H NMR (400 MHz, CDCl3): δ 6.85 (dd, J = 6.0, 1.2
Hz, 1H), 6.66 (m, 2H) (olefinic CH), 4.21 (dt, J = 5.6, 1.6 Hz, 1H),
4.17 (td, J = 6.0, 1.6 Hz, 1H) (CH), 0.13 (s, 9H) (Si(CH3)3). 13C{1H}
NMR (100 MHz, CDCl3): δ 154.3, 149.6, 141.8, 140.8, 47.1, 45.5,
−2.9, the cage carbons were not observed. 11B{1H} NMR (128 MHz,
CDCl3): δ −2.1 (2B), −3.1 (2B), −12.4 (6B). HRMS (EI): calcd for
MHz, CDCl3): δ 0.0 (2B), −2.3 (1B), −4.2 (2B), −9.7 (8B), −11.8
11
(7B). HRMS (EI): calcd for C11H26
found 374.4033.
B
10B4+ ([M − 2H]+) 374.4035,
16
6a:10 white powder (14.1 mg, 6%). H NMR (400 MHz, acetone-
d6): δ 7.36 (m, 3H), 7.27 (m, 2H) (aromatic CH), 4.51 (br, 1H) (cage
CH), 3.69 (s, 2H) (CH2). 11B{1H} (128 MHz, acetone-d6): δ −1.6
(1B), −4.8 (1B), −8.4 (2B), −10.1 (2B), −10.9 (2B), −11.8 (2B).
7a: colorless crystals (11.3 mg, 6%). 1H NMR (400 MHz, CDCl3):
δ 6.13 (m, 2H), 5.92 (d, J = 9.2 Hz, 1H), 5.77 (m, 1H) (olefinic CH),
3.95 (d, J = 6.4 Hz, 1H) (CH), 3.72 (d, J = 12.4 Hz, 1H) (CHH), 3.61
(br, 1H) (cage CH), 2.93 (d, J = 12.8 Hz, 1H) (CHH). 13C{1H} NMR
(100 MHz, CDCl3): δ 133.1, 126.4, 126.2, 125.1, 86.2 (cage C), 73.0
(cage C), 70.9 (cage C), 58.9 (cage C), 54.4, 46.8, 44.2. 11B{1H} (96
MHz, CDCl3): δ −1.6 (2B), −3.1 (br, 3B), −10.6 (br, 15B). HRMS
1
+
C11H24Si11B810B2 292.2652, found 292.2659.
4d+4d′: white solid (133.5 mg, 54%, 4d/4d′ = 70/30). 4d was
obtained in pure form by recrystallization from hexane. 4d: colorless
crystals. 1H NMR (400 MHz, CDCl3): δ 6.66 (t, J = 6.8 Hz, 1H), 6.29
(m, 2H) (olefinic CH), 3.93 (m, 1H) (CH), 1.79 (d, J = 1.2 Hz, 3H),
1.55 (s, 3H) (CH3). 13C{1H} NMR (100 MHz, CDCl3): δ 151.6,
146.3, 141.3, 137.7, 81.4 (cage C), 80.7 (cage C), 52.5, 43.9, 17.2, 16.6.
11B{1H} NMR (96 MHz, CDCl3): δ −1.2 (4B), −11.6 (6B). HRMS
(EI): calcd for C10H2011B810B2+ 248.2563, found 248.2553. Anal. Calcd
for C10H20B10: C, 48.36; H, 8.12. Found: C, 48.37; H, 8.13. 4d′: The
data were collected from the mixture of 4d and 4d′, as it was unable to
11
+
(EI): calcd for C11H28
B
10B4 376.4192, found 376.4192.
16
1
8a: colorless crystals (7.3 mg, 3%). 1H NMR (400 MHz, CDCl3): δ
7.36 (d, J = 8.0 Hz, 1H), 7.32 (dd, J = 7.2, 1.6 Hz, 1H), 7.29 (m, 1H),
7.21 (d, J = 7.6 Hz, 1H) (aromatic CH), 3.69 (s, 2H) (CH2). 13C{1H}
NMR (100 MHz, CDCl3): δ 144.4, 138.6, 128.9, 127.8, 125.7, 121.4,
84.6 (cage C), 40.9, one cage carbon was not observed. 11B{1H} (128
MHz, CDCl3): δ −6.6 (br, 4B), −8.7 (2B), −11.5 (2B), −12.8 (2B).
This is a known compoud,11 but no NMR data were reported.
Pyrolysis of 4a′. A glass tube sealed with 4a′ (46.8 mg, 0.2 mmol)
under vacuum was heated at 250 °C for 4 h in a Muffle furnace. After
cooling to room temperature, the reaction mixture was purified by
flash column chromatography on silica gel (230−400 mesh) using n-
hexane/ether (n-hexane/ether = 100/1 in v/v) as eluent to give 5a as
colorless crystals (29.7 mg, 79%).
be isolated in pure form. H NMR (400 MHz, CDCl3): δ 6.66 (m,
2H) (olefinic CH), 3.76 (br, 2H) (CH), 1.72 (s, 6H) (CH3). 13C{1H}
NMR (100 MHz, CDCl3): δ 142.5, 140.1, 79.0 (cage C), 50.3, 16.8.
4e+4e′: white solid (139.8 mg, 56%, 4e/4e′ = 68/32). 4e was
obtained in pure form by recrystallization from hexane. 4e: colorless
crystals. 1H NMR (400 MHz, CDCl3): δ 6.64 (t, J = 6.8 Hz, 1H), 6.36
(dd, J = 6.8, 1.2 Hz, 1H), 5.90 (s, 1H) (olefinic CH), 3.71 (dt, J = 6.0,
1.2 Hz, 1H) (CH), 1.86 (d, J = 1.6 Hz, 3H), 1.60 (s, 3H) (CH3).
13C{1H} NMR (100 MHz, CDCl3): δ 150.8, 146.7, 141.0, 140.3, 83.7
(cage C), 78.7 (cage C), 50.0, 49.8, 19.7, 19.3. 11B{1H} NMR (96
MHz, CDCl3): δ −1.3 (4B), −11.7 (6B). HRMS (EI): calcd for
C10H2011B810B2+ 248.2563, found 248.2554. Anal. Calcd for C10H20B10:
C, 48.36; H, 8.12. Found: C, 48.34; H, 8.33. 4e′: The data were
collected from the mixture of 4e and 4e′, as it was unable to be isolated
in pure form. 1H NMR (400 MHz, CDCl3): δ 6.22 (dt, J = 6.4, 1.6 Hz,
2H) (olefinic CH), 3.91 (t, J = 6.4 Hz, 1H), 3.46 (t, J = 1.6 Hz, 1H)
(CH), 1.88 (d, J = 2.0 Hz, 6H) (CH3). 13C{1H} NMR (100 MHz,
CDCl3): δ 149.2, 135.9, 81.7 (cage C), 76.5 (cage C), 55.1, 44.1, 19.9.
4g+4g′: white solid (125.9 mg, 51%, 4g/4g′ = 12/88). 4g′ was
obtained in pure form by recrystallization from hexane. 4g: The data
were collected from the mixture of 4g and 4g′, as it was unable to be
5b. This compound was prepared as colorless crystals from the
pyrolysis of 4b (55.3 mg, 0.2 mmol) using the same procedure
1
reported for 5a: 40.0 mg, 95%. H NMR (400 MHz, CDCl3): δ 3.85
(s, 1H), 3.04 (s, 2H), 1.51 (s, 2H) (CH), 1.14 (s, 9H) (C(CH3)3).
13C{1H} NMR (100 MHz, CDCl3): δ 80.0 (cage C), 69.8 (cage C),
69.2 (cage C), 52.4, 50.2, 47.2, 37.2, 29.2, one cage carbon was not
observed and the signal at 47.2 ppm may be assigned for two carbons.
11B{1H} (128 MHz, CDCl3): δ −1.0 (2B), −2.9 (2B), −9.2 (5B),
1
isolated in pure form. H NMR (400 MHz, CDCl3): δ 6.34 (s, 4H)
11
−10.4 (5B), −13.1 (6B). HRMS (EI): calcd for C14H33
B
10B4+ ([M
16
1
(olefinic CH), 1.61 (s, 6H) (CH3). 4g′: colorless crystals. H NMR
− H]+) 417.4583, found 417.4568.
(400 MHz, CDCl3): δ 6.19 (dt, J = 6.4, 2.0 Hz, 2H) (olefinic CH),
3.67 (dd, J = 6.4, 2.0 Hz, 2H) (CH), 1.87 (d, J = 1.6 Hz, 6H) (CH3).
13C{1H} NMR (75 MHz, CDCl3): δ 150.9, 134.4, 79.1 (cage C), 49.6,
19.8. 11B{1H} NMR (96 MHz, CDCl3): δ −1.9 (1B), −5.0 (1B), −8.3
Reactions of 2 with 3b−e, 3g, and 3i. These reactions were
performed at a scale of 1.0 mmol of 2 using the same procedures
reported for 3a.
4b+4b′: white solid (185.7 mg, 67%, 4b/4b′ = 73/27). 4b was
obtained in pure form by recrystallization from hexane. 4b: colorless
crystals. 1H NMR (400 MHz, CDCl3): δ 6.73 (t, J = 6.8 Hz, 2H), 6.65
(dd, J = 6.8, 1.6 Hz, 2H) (olefinic CH), 3.94 (m, 1H) (CH), 1.25 (br,
9H) (C(CH3)3). 13C{1H} NMR (100 MHz, CDCl3): δ 143.1, 141.2,
82.1 (cage C), 80.6 (cage C), 64.5, 43.6, 34.9, 27.5 (br). 11B{1H} NMR
(128 MHz, CDCl3): δ −1.5 (1B), −3.5 (3B), −11.1 (2B), −13.3 (2B),
+
(2B), −9.9 (2B), −12.4 (4B). HRMS (EI): calcd for C10H2011B810B2
248.2563, found 248.2555. Anal. Calcd for C10H20B10: C, 48.36; H,
8.12. Found: C, 48.38; H, 8.22.
4i: colorless crystals (169.5 mg, 65%). 1H NMR (400 MHz,
CDCl3): δ 5.90 (s, 2H) (olefinic CH), 3.38 (t, J = 1.6 Hz, 1H) (CH),
1.86 (d, J = 1.6 Hz, 6H), 1.55 (s, 3H) (CH3). 13C{1H} NMR (75
MHz, CDCl3): δ 149.6, 141.2, 85.8 (cage C), 78.3 (cage C), 55.1, 49.7,
19.9, 19.3. 11B{1H} NMR (96 MHz, CDCl3): δ −1.6 (4B), −12.0
+
−14.2 (2B). HRMS (EI): calcd for C12H2411B810B2 276.2876, found
(6B). HRMS (EI): calcd for C11H2211B810B2 262.2719, found
+
276.2874. Anal. Calcd for C12H24B10: C, 52.14; H, 8.75. Found: C,
52.37; H, 8.59. 4b′: The data were collected from the mixture of 4b
262.2711. Anal. Calcd for C11H22B10: C, 50.35; H, 8.45. Found: C,
50.08; H, 8.58.
1
and 4b′, as it was unable to be isolated in pure form. H NMR (400
MHz, CDCl3): δ 6.66 (m, 2H), 6.15 (dd, J = 6.4, 2.0 Hz, 1H) (olefinic
CH), 4.11 (m, 1H), 4.06 (m, 1H) (CH), 1.05 (s, 9H) (C(CH3)3).
13C{1H} NMR (100 MHz, CDCl3): δ 161.7, 142.3, 141.2 (overlapped
with one of 4b’s), 131.1, 78.7 (cage C), 46.0, 44.3, 34.2, 27.0, one cage
carbon was not observed.
4c+4c′: white solid (151.1 mg, 52%, 4c/4c′ = 35/65). Both 4c and
4c′ were obtained in pure form by recrystallization from hexane. 4c:
colorless crystals. 1H NMR (400 MHz, CDCl3): δ 6.82 (t, J = 6.8 Hz,
2H), 6.53 (dd, J = 6.8, 1.2 Hz, 2H) (olefinic CH), 4.05 (t, J = 6.4 Hz,
1H) (CH), 0.25 (s, 9H) (Si(CH3)3). 13C{1H} NMR (100 MHz,
CDCl3): δ 144.3, 143.6, 81.2 (cage C), 80.9 (cage C), 44.4, 44.3, −2.2.
11B{1H} NMR (128 MHz, CDCl3): δ −1.8 (1B), −2.3 (2B), −2.8
Reaction of 2 with 3f. To an in situ prepared cyclohexane
solution (10 mL) of 1 (1.0 mmol) at room temperature was added 3f
(147.6 mg, 1.1 mmol). The reaction mixture was heated at 110 °C
overnight and then quenched with wet n-hexane. The resulting
suspension was quickly passed through a short column of silica gel to
remove the inorganic salts and washed with ether. The organic
portions were combined. After removal of solvents in vacuo, the
1
residue was analyzed by H NMR spectroscopy and then subject to
flash column chromatography on silica gel (230−400 mesh) using n-
hexane as eluent to give 4f+4f′ as a white solid (124.0 mg, 45%, 4f/4f′
= 70/30). Both 4f and 4f′ were obtained in pure form by
recrystallization from hexane. 4f: colorless crystals. 1H NMR (400
3321
dx.doi.org/10.1021/om300129t | Organometallics 2012, 31, 3316−3323