Organometallics
Article
(126 MHz, DMSO-d6): δ (ppm) 182.9 (carbenic-C), 139.9 (C),
137.7 (C), 136.1 (C), 135.4 (C), 129.6 (CH), 129.4 (CH), 129.1
(CH), 127.4 (CH), 123.0 (NCH), 122.4 (NCH), 53.4 (CH2), 38.0
(CH2), 21.4 (CH3), 17.9 (CH3). HRMS (ESI+): m/z [C40H44AgN4]+
689.2621, calcd for [M − Br]+ 689.2615. Anal. Calcd for C, 62.51; H,
5.77; N, 7.29. Found: C, 62.38; H, 5.89; N, 7.17.
CCH3). 13C NMR (126 MHz, CDCl3): δ (ppm) 154.7 (CO), 151.5
(CO), 149.5 (C), 142.4 (NCHN), 107.4 (C), 77.4 (carboranyl-C),
75.9 (carboranyl-CCH3), 42.5 (CH2), 33.9 (CH3), 30.2 (CH3), 23.5
(carboranyl-CCH3). 11B{1H} NMR (161 MHz, CDCl3): δ (ppm)
−3.2, −6.0, −9.9. HRMS (ESI+): m/z [C11H23B10N4O2]+ 351.2824,
calcd for [M + H]+ 351.2824.
T6. This compound was prepared as described for T4 from
theobromine (3.00 g, 16.70 mmol), Cs2CO3 (10.80 g, 33.30 mmol),
and 4-bromo-1-butyne (1.88 mL, 20.00 mmol) in CH3CN (30 mL).
After workup the product was obtained as a white powder. Yield: 1.55
g, 6.68 mmol (40%). 1H NMR (300 MHz, CDCl3): δ (ppm) 7.50 (s,
1H, NCHN), 4.23−4.20 (m, 2H, CH2), 3.98 (s, 3H, CH3), 3.56 (s,
3H, CH3), 2.58 (td, J = 7.3, 2.7 Hz, 2H, CH2), 1.96 (t, J = 2.7 Hz, 1H,
CH). 13C NMR (75 MHz, CDCl3): δ (ppm) 155.1 (CO), 151.4
(CO), 149.0 (C), 141.7 (NCHN), 107.7 (C), 81.0 (CCH), 69.9
(CH2), 39.7 (CH2), 33.7 (CH3), 29.8 (CH3), 17.8 (CCH). HRMS
(ESI+): m/z 255.0860 [C11H12N4O2Na]+, calcd for [M + Na]+
255.0858.
T4. In a round-bottom flask were placed CH3CN (30 mL),
theobromine (3.00 g, 16.70 mmol), Cs2CO3 (10.80 g, 33.30 mmol),
and propargyl bromide (2.27 mL, 25.00 mmol, 80 wt % toluene), and
the mixture was heated at 80 °C for 18 h. The reaction mixture was
cooled to room temperature and the solvent removed in vacuo.
CH2Cl2 (50 mL) was added, the mixture was filtered, and H2O (30
mL) was added to the filtrate, with the organic phase being collected.
This was further washed with H2O (2 × 30 mL), dried over MgSO4,
and filtered and the solvent removed in vacuo. The off-white residue
was recrystallized from CH2Cl2 (20 mL) with pentane (50 mL) to
give a white powder. Yield: 2.99 g, 13.70 mmol (82%). 1H NMR (500
MHz, CDCl3): δ (ppm) 7.52 (m, 1H, NCHN), 4.79 (d, J = 2.5 Hz,
2H, CH2), 3.99 (m, 3H, CH3), 3.59 (s, 3H, CH3), 2.17 (t, J = 2.5 Hz,
1H, CH). 13C NMR (126 MHz, CDCl3): δ (ppm) 154.5 (CO), 151.0
(CO), 149.3 (C), 141.9 (NCHN), 107.7 (C), 78.8 (CCH), 70.6
(CCH), 33.8 (CH3), 30.6 (CH2), 29.9 (CH3). HRMS (ESI+): m/z
[C10H10N4O2Na]+ 241.0700, calcd for [M + Na]+ 241.0696.
P4. In a Schlenk flask were placed T4 (1.00 g, 4.58 mmol) and
B10H12(CH3CN)2 (927 mg, 4.58 mmol), and the flask was degassed.
Anhydrous toluene (10 mL) and anhydrous CH3CN (3 mL) were
added, and the mixture was slowly heated to 100 °C and kept at this
temperature for 18 h. The reaction mixture was cooled to room
temperature and the solvent removed in vacuo. Et2O (2 × 15 mL)
was added to the product and filtered to remove insoluble material.
The filtrate was washed with 1 M NaOH solution (2 × 10 mL) and
H2O (2 × 10 mL), dried over MgSO4, and filtered and the solvent
removed from the filtrate in vacuo. The residue was recrystallized
from Et2O (10 mL) with hexane (30 mL) and filtered and the white
solid dried in vacuo. Yield: 807 mg, 2.40 mmol (52%). 1H NMR (500
MHz, CDCl3): δ (ppm) 7.56 (s, 1H, NCHN), 4.88 (d, J = 14.9 Hz,
1H, CH2), 4.60 (d, J = 14.9 Hz, 1H, CH2), 4.20 (br. s, 1H,
carboranyl-CH), 3.98 (s, 3H, CH3), 3.58 (s, 3H, CH3). 13C NMR
(126 MHz, CDCl3): δ (ppm) 154.5 (CO), 151.6 (CO), 149.4 (C),
142.6 (NCHN), 107.3 (C), 74.0 (carboranyl-C), 61.3 (carboranyl-
CH), 45.3 (CH2), 33.9 (CH3), 30.2 (CH3). 11B{1H} NMR (161
MHz, CDCl3): δ (ppm) −1.4, −4.8, −10.0, −10.8, −12.9. HRMS
(ESI+): m/z [C10H21B10N4O2]+ 337.2670, calcd for [M + H]+
337.2667.
P6. In a Schlenk flask were placed T6 (1.00 g, 4.31 mmol) and
B10H12(CH3CN)2 (871 mg, 4.31 mmol), and the flask was degassed.
Anhydrous toluene (10 mL) and anhydrous CH3CN (3 mL) were
added, and the reaction mixture was slowly heated to 100 °C and kept
at this temperature for 18 h. The reaction mixture was cooled to room
temperature and the solvent removed in vacuo. The residue was
dissolved in a minimum amount of CH2Cl2 and purified by silica
chromatography, by elution with ethyl acetate/hexane 1/2, and then
the product was eluted with CH2Cl2/CH3OH (10%). The product
fractions were combined, and the solvent was removed in vacuo. The
residue was dissolved in Et2O (5 mL) and the product precipitated as
a white powder with hexane (30 mL), filtered, and dried in vacuo.
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Yield: 680 mg, 1.93 mmol (45%). H NMR (300 MHz, CDCl3): δ
(ppm) 7.52 (s, 1H, NCHN), 4.12 (m, 2H, CH2), 3.96 (s, 3H, CH3),
3.73 (br. s, 1H, carboranyl-CH), 3.55 (s, 3H, CH3), 2.52 (m, 2H,
CH2). 13C NMR (75 MHz, CDCl3): δ (ppm) 154.8 (CO), 151.2
(CO), 149.2 (C), 142.0 (NCHN), 107.6 (C), 72.4 (carboranyl-CH),
61.6 (carboranyl-C), 40.0 (CH2), 35.12 (CH2), 33.8 (CH3), 29.89
(CH3). 11B{1H} NMR (96 MHz, DMSO-d6): δ (ppm) −2.1, −5.3,
−9.1, −11.6. HRMS (ESI+): m/z [C13H23B10N5O2Na]+ 413.2600,
calcd for [M + CH3CN + Na−2H]+ 413.2716. (Note: only one of the
CH2 resonance is observed).
T7. This compound was prepared as described for T4 from
theobromine (3.00 g, 16.70 mmol), Cs2CO3 (10.80 g, 33.30 mmol),
and benzyl bromide (1.99 mL, 16.70 mmol) in CH3CN (30 mL).
After workup the product was obtained as a white powder. Yield: 3.62
1
T5. This compound was prepared as described for T4 from
theobromine (3.00 g, 16.70 mmol), Cs2CO3 (10.80 g, 33.30 mmol),
and 1-bromo-2-butyne (1.60 mL, 18.40 mmol) in CH3CN (30 mL).
After workup the product was obtained as a white powder. Yield: 2.95
g, 13.40 mmol (80%). H NMR (500 MHz, CDCl3): δ (ppm) 7.49
(m, 3H, 1H, NCHN), 7.30 (m, 2H, Ar-CH), 7.24 (m, 1H, Ar-CH),
5.19 (s, 2H, CH2), 3.98 (m, 3H, CH3), 3.57 (s, 3H, CH3). 13C NMR
(126 MHz, CDCl3): δ (ppm) 155.4 (CO), 151.8 CO), 149.0 (C),
141.7 (NCHN), 137.5 (Ar-C), 129.0 (Ar-CH), 128.5 (Ar-CH), 127.7
(Ar-CH), 107.8 (C), 44.6 (CH2), 33.7 (CH3), 29.9 (CH3). HRMS
(ESI+): m/z [C14H14N4O2Na]+ 293.1025, calcd for [M + Na]+
293.1009.
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g, 12.70 mmol (76%). H NMR (500 MHz, CDCl3): δ (ppm) 7.50
(m, 1H, NCHN), 4.72 (q, J = 2 Hz, 2.5 Hz, 2H, CH2), 3.98 (s, 3H,
CH3), 3.58 (s, 3H, CH3), 1.76 (t, J = 2 Hz, 3H, CH3). 13C NMR (126
MHz, CDCl3): δ (ppm) 154.7 (CO), 151.1 (CO), 149.1 (C), 141.7
(NCHN), 107.7 (C), 78.3 (CC), 73.9 (CC), 33.7 (CH3), 31.1
(CH2), 29.9 (CH3), 3.8 (CH3). HRMS (ESI+): m/z
[C11H12N4O2Na]+ 255.0857, calcd for [M + Na]+ 255.0852.
L4. An ampule was charged with CH3CN (5 mL), P4 (1.17 g, 3.48
mmol), and MeI (6.49 mL, 104.3 mmol) and heated at 80 °C for 7
days. The reaction mixture was cooled to room temperature and the
solvent removed in vacuo. To the residue was added Et2O (30 mL),
which was then sonicated, and the solid was filtered, washed with
Et2O (20 mL), and dried in vacuo to give a white powder. Yield: 631
P5. In a Schlenk flask were placed T5 (1.00 g, 4.31 mmol) and
B10H12(CH3CN)2 (871 mg, 4.31 mmol), and the flask was degassed.
Anhydrous toluene (10 mL) and anhydrous CH3CN (3 mL) were
added, and the reaction mixture was slowly heated to 100 °C and kept
at this temperature for 18 h. The reaction mixture was cooled to room
temperature and the solvent removed in vacuo. The residue was
dissolved in a minimum amount of CH2Cl2 and purified by silica
chromatography, by elution with ethyl acetate/hexane 1/2. The
product fractions were combined, and the solvent was removed in
vacuo. The residue was dissolved in Et2O (5 mL) and the product was
precipitated as a white powder with hexane (30 mL), which was
1
mg, 1.46 mmol (42%). H NMR (500 MHz, DMSO-d6): δ (ppm)
9.35 (s, 1H, NCHN), 5.11 (br. s, 1H, carboranyl-CH), 4.81 (d, J =
15.1 Hz, 1H, CH2), 4.58 (d, J = 15.1 Hz, 1H, CH2), 4.16 (s, 3H,
CH3), 4.06 (s, 3H, CH3), 3.76 (s, 3H, CH3). 13C NMR (126 MHz,
DMSO-d6): δ (ppm) 152.7 (CO), 150.1 (CO), 140.5 (NCHN),
139.9 (C), 107.5 (C), 73.2 (carboranyl-C), 62.4 (carboranyl-CH),
45.1 (CH2), 37.0 (CH3), 35.8 (CH3), 31.8 (CH3). 11B{1H} NMR
(161 MHz, DMSO-d6): δ (ppm) −2.9, −5.2, −10.0, −11.6, −13.0.
HRMS (ESI+): m/z [C11H23B10N4O2]+ 352.2800, calcd for [M − I]+
352.2800.
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filtered and dried in vacuo. Yield: 573 mg, 1.63 mmol (38%). H
NMR (500 MHz, CDCl3): δ (ppm) 7.56 (d, J = 0.6 Hz, 1H, NCHN),
4.86 (d, J = 14.8 Hz, 1H, CH2), 4.64 (d, J = 14.8 Hz, 1H, CH2), 3.99
(d, J = 0.6 Hz, 3H, CH3), 3.59 (s, 3H, CH3), 2.34 (s, 3H, carboranyl-
L5. This compound was prepared as described for L4 from P5
(500 mg, 1.43 mmol) and MeI (2.67 mL, 42.6 mmol) in CH3CN (5
G
Organometallics XXXX, XXX, XXX−XXX