Inorganic Chemistry
Article
C4D8O (THF-d8) were distilled from sodium followed by drying over
potassium mirror and degassed three times using freeze−pump−thaw
cycling and stored in an argon-filled glovebox for NMR measurements
of 4, 5·(THF)2, 6·(THF)2, 5·TMEDA, 6·TMEDA, and tBu2Zn. Other
chemicals were used as supplied. Column chromatography was carried
out using Kanto silica gel 60N (spherical, neutral) or Merck KGaA
aluminum oxide 90 acc. to Brockmann (activity II−III).
at ambient temperature for 1 h, from which colorless crystals were
obtained. The reaction mixture was centrifuged at 20 °C for 2 min at a
speed of 3000 rpm. The supernatant was removed by syringe. The
remaining crystals were washed with hexane (5 mL), and the washing
was separated and removed as described above. The remaining solid in
a small amount of hexane was filtered under argon atmosphere to give
LiCPC (4) (118 mg, 0.517 mmol, 92%) as colorless crystals suitable
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General Measurements. H NMR (400 MHz), 13C NMR (100
for X-ray crystallographic analysis. H NMR (C6D6, 400 MHz): δ =
MHz), and 7Li NMR (155 MHz) spectra were recorded using a JEOL
EX-400 or AL-400 NMR spectrometer. The 1H and 13C NMR
chemical shifts (δ scale) are determined by residual protons of the
solvent (1H, CDCl3, δ = 7.26 ppm; C6D6, δ = 7.20 ppm; C4D8O, δ =
3.58 ppm) or the solvent itself (13C, CDCl3, δ = 77.0 ppm; C6D6, δ =
2.09−1.98 (2H, m), 1.80−1.13 (20H, m), 1.00−0.83 ppm (4H, m).
13C NMR (C4D8O, 100 MHz): δ = 54.26 (C), 45.80 (CH2), 39.70
(CH2), 32.54 (CH2), 28.69 (CH2), 23.53 (CH2), 20.29 (CH2), 14.44
ppm (CH2). 7Li NMR (C6D6, 155 MHz, LiCl in D2O): δ = 2.75 ppm.
THF-Coordinated Zincate Complexes, 5·(THF)2 and 6·(THF)2. n-
Butyllithium (1.63 M in hexane, 1.25 mL, 2.04 mmol for 5·(THF)2, or
1.85 mL, 3.02 mmol for 6·(THF)2) was added dropwise to 2 (neat,
443 mg, 2.00 mmol for 5·(THF)2) or TMP(H) (neat, 0.500 mL, 2.96
mmol for 6·(THF)2) at −78 °C. After stirring at −78 °C for 1 h,
diethyl zinc (1.06 M in hexane, 2.00 mL, 2.12 mmol for 5·(THF)2, or
3.00 mL, 3.18 mmol for 6·(THF)2) was added and the resultant slurry
was warmed to ambient temperature. THF (3.0 mL for 5·(THF)2, or
2.0 mL for 6·(THF)2) was then added to the reaction mixture to give a
homogeneous solution and concentrated under reduced pressure. The
resultant solution was stored at −80 °C for 1 day, from which two
phases formed. The top layer is a solvent mixture of THF and hexane,
which is removed using a syringe. The bottom phase is frozen 5·
(THF)2 or 6·(THF)2 in THF, which was stored at −30 °C for 1 day
under argon atmosphere to afford 5·(THF)2 or 6·(THF)2 as a white
solid. This was filtered and washed with hexane (3 × 2 mL) to afford
pure 5·(THF)2 (473 mg, 0.955 mmol, 48%) or 6·(THF)2 (620 mg,
1.49 mmol, 50%). Recrystallization from hexane at −30 °C gave
crystals suitable for X-ray crystallographic analysis.
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128.0 ppm; C4D8O, δ = 67.4 ppm). The Li NMR chemical shifts are
referenced to LiCl in D2O at 0 ppm. Melting points were measured
with a Yanagimoto micromelting point apparatus and are uncorrected.
The elemental analyses were performed using a PerkinElmer
2400CHNS elemental analyzer.
Preparation and Characterization. CPC(H) (2). The DMSO
used in this step was not dried. Hydrazine monohydrate (0.360 mL,
7.40 mmol) was added to a solution of 7-azadispiro[5.1.5.3]hexadecan-
15-one (1) (64.1 g, 271 mmol) in DMSO (180 mL) at 60 °C. The
solution was stirred at 80 °C for 1 h before KOH (186 mg, 3.33
mmol) was added at the same temperature. The resulting mixture was
heated to 130 °C for 6 h before being heated to 190 °C to remove
water azeotropically (over 12 h). The resulting solution was cooled to
ambient temperature before water (120 mL) and toluene (75 mL)
were added. The mixture was stirred at room temperature for 1 h and
acidified with aqueous HCl solution (10%, pH 1−2). The precipitate
was filtered and washed with ether. The filtrate was adjusted to pH 9
using an aqueous K2CO3 solution and then extracted with AcOEt (4 ×
400 mL). The combined organic layer was washed with saturated
aqueous NaCl solution and dried over Na2SO4. The filtered precipitate
was added to water (ca. 1 L), and the suspension was also adjusted to
pH 9 using aqueous K2CO3 solution and then extracted with AcOEt (4
× 400 mL). The combined organic layer was washed with saturated
aqueous NaCl solution and dried over Na2SO4. All AcOEt extracts
were combined and concentrated under reduced pressure. The
residual brown oil was preliminarily purified by column chromatog-
raphy (aluminum) with AcOEt as the eluent. The resultant orange oil
was further purified by distillation under reduced pressure (ca. 62 °C/
0.2 mmHg) to give CPC(H) (2) (44.9 g, 203 mmol, 75%) as a
colorless oil. After this oil was cooled at −30 °C, the oil solidified into
a white solid. Recrystallization of this solid from CH2Cl2 at −30 °C
afforded crystals suitable for X-ray crystallographic analysis. Mp 34−35
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5·(THF)2. H NMR (C6D6, 400 MHz): δ = 3.46 (8H, m), 2.35
(2H, d, J = 12 Hz), 2.13 (2H, m), 1.91 (6H, t, J = 8 Hz), 1.84−1.00
(30H, m), 0.58 ppm (4H, q, J = 8 Hz). 13C NMR (C6D6, 100 MHz): δ
= 68.27 (CH2), 55.47 (C), 46.23 (CH2), 41.69 (CH2), 35.71 (CH2),
26.93 (CH2), 25.40 (CH2), 24.42 (CH2), 24.04 (CH2), 18.64 (CH2),
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13.80 (CH3), 5.81 ppm (CH2). Li NMR (C6D6, 155 MHz, LiCl in
D2O): δ = 1.42 ppm.
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6·(THF)2. H NMR (C6D6, 400 MHz): δ = 3.42 (8H, m), 2.08−
1.65 (10H, m), 1.48 (6H, s), 1.38−1.02 (16H, m), 0.51 ppm (4H, q, J
= 8 Hz). 13C NMR (C6D6, 100 MHz): δ = 68.27 (CH2), 52.79 (C),
41.04 (CH2), 36.19 (CH3), 32.01 (CH3), 25.32 (CH2), 20.05 (CH2),
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13.56 (CH3), 5.24 ppm (CH2). Li NMR (C6D6, 155 MHz, LiCl in
D2O): δ = 1.03 ppm.
TMEDA-Coordinated Zincate Complexes, 5·TMEDA and 6·
TMEDA. Recrystallization of 5·(THF)2 (175 mg, 0.354 mmol) or 6·
(THF)2 (154 mg, 0.370 mmol) from neat TMEDA afforded 5·
TMEDA (82.3 mg, 0.176 mmol, 50%) or 6·TMEDA (109 mg, 0.282
mmol, 76%) as colorless crystals suitable for X-ray crystallographic
analysis.
°C. 1H NMR (CDCl3, 400 MHz): δ = 1.13−2.00 ppm (26H, m). 13
C
NMR (CDCl3, 100 MHz): δ = 51.24 (C), 40.30 (CH2), 36.08 (CH2),
26.28 (CH2), 22.52 (CH2), 17.03 ppm (CH2). Anal. Calcd for
C15H27N: C, 81.38; H, 12.29; N, 6.33. Found: C, 81.77; H, 12.22; N,
6.61.
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CPC(Me) (3). Formic acid (0.190 mL, 5.00 mmol) was added
dropwise to a toluene (20 mL) solution of 2 (1.00 g, 4.52 mmol) and
paraformaldehyde (190 mg, 6.34 mmol) at 90 °C. The reaction
mixture was heated to 130 °C for 18 h with stirring followed by
another hour at 100 °C before being cooled to ambient temperature,
to which NaOH (108 mg, 2.70 mmol) was added as a solid. The
mixture was stirred for 1 h, and the sodium hydroxide was filtered off.
The solvent was concentrated, and the residual solid was purified by
column chromatography (silica gel) with AcOEt as the eluent to give
CPC(Me) (3) (155 mg, 0.698 mmol, 70%) as a white solid (Rf =
0.07). Recrystallization from CH3CN at ambient temperature gave
5·TMEDA. H NMR (C6D6, 400 MHz): δ = 2.36−0.83 (48H, m),
0.41 ppm (4H, q, 3J = 7.8 Hz). 13C NMR (C6D6, 100 MHz): δ = 57.17
(CH2), 55.46 (C), 46.84 (CH3), 43.49 (CH2), 43.14 (CH2), 33.03
(CH2), 26.36 (CH2), 24.23 (CH2), 23.62 (CH2), 18.63 (CH2), 14.34
(CH3), 6.27 ppm (CH2). 7Li NMR (C6D6, 155 MHz, LiCl in D2O): δ
= 0.75 ppm.
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6·TMEDA. H NMR (C6D6, 400 MHz): δ = 2.16−1.71 (26H, m),
1.65−1.46 (2H, m), 1.25 (12H, s), 0.32 ppm (4H, q, 3J = 7.8 Hz). 13
C
NMR (C6D6, 100 MHz): δ = 57.19 (CH2), 52.91 (C), 46.79 (CH3),
38.66 (CH2), 35.99 (CH3), 33.70 (CH3), 20.00 (CH2), 14.24 (CH3),
5.59 ppm (CH2). 7Li NMR (C6D6, 155 MHz, LiCl in D2O): δ = 0.70
ppm.
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crystals suitable for X-ray crystallographic analysis. Mp 58−59 °C. H
NMR (CDCl3, 400 MHz): δ = 2.33 (3H, s), 1.80−1.18 (24H, m),
1.10−0.91 ppm (2H, m). 13C NMR (CDCl3, 100 MHz): δ = 56.95
(C), 33.81 (CH2), 33.28 (CH2), 27.10 (CH3), 25.95 (CH2), 23.23
(CH2), 16.28 ppm (CH2). Anal. Calcd for C16H29N: C, 81.63; H,
12.42; N, 5.95. Found: C, 81.81; H, 12.80; N, 6.03.
LiCPC (4). n-Butyllithium (1.60 M in hexane, 0.35 mL, 0.56 mmol)
was added dropwise to a hexane (5.0 mL) solution of 2 (125 mg,
0.562 mmol) at 0 °C with no stirring. The still reaction mixture stood
Competitive Methylation Reaction. n-Butyllithium (1.60 M in
hexane, 3.50 mL, 5.60 mmol) was added to a THF solution (28.0 mL)
of TMP(H) (393 mg, 2.78 mmol) and 2 (616 mg, 2.78 mmol)
dropwise at −78 °C. After addition, the reaction mixture was slowly
warmed to 0 °C and stirred at 0 °C for 1 h. MeOTf (0.300 mL, 2.65
mmol) was added to the resulting suspension, and the reaction
mixture was stirred at 0 °C for 12 h. The residual lithium amides were
quenched by addition of iPrOH at 0 °C. Afterward, the solution was
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Inorg. Chem. XXXX, XXX, XXX−XXX