Alkyllithium Compounds
225±236
extracted with four portions of diethyl ether (125 mL). After drying over
sodium sulfate and removal of solvent, the residue was submitted to
molecular distillation (258C, 10 2 Torr, condensation finger cooled by
liquid nitrogen). Yield: 8 g (36 mmol, 60%) of a colourless oil which was
stored at 808C. 1H NMR: d 3.66 (d, J 3.7 Hz, 2H), 2.40 ± 2.15 (m,
5H), 2.24 (s, 12H).
signals of Hb and Hc' (or Hc) between 2.30 and 1.90 are hidden under the
NMe2 signals; 1H NMR (298 K): Ha: d 1.150 (very broad); Hc (or Hc'):
d ? (extremely broad); NMe2: d 2.138; 13C NMR (213 K): Ca: d 17.06,
(ªtº, very broad); Cb: d 36.29, 35.94, 35.78 (d, J(CH) 120 Hz); Cc,c': d
74.62, 69.15 (t, J(C,H) 127 Hz); NMe2: d 49.53 (A), 48.43 (A), 46.35
(B), 45.12 (B) 44.06 (A) (q, J(C,H) 130 Hz); 13C NMR (298 K): Ca: d
17.13 (very broad); Cb: d 36.55 (d, J(C,H) 120 Hz); Cc,c': d 74.81, 69.81,
(brt, J(C,H) 127 Hz); NMe2: d 48.76 (very broad), 46.37 (q, J(CH)
130 Hz).
c) (1,1-Bis(dimethylaminomethyl)-2-ethyl)mercuric bromide: Under reflux,
2-bromo-1,1-bis(dimethylaminomethyl)ethane (4.3 g, 19.4 mmol) dissolved
in THF (250 mL) was added under nitrogen over 200 min to magnesium
shavings (1.4 g, 58 mmol) in THF (10 mL). After 45 min reflux, filtration
through glass wool and titration (yield 90%), the Grignard reagent was
added at room temperature over 180 min to HgBr2 (9 g) dissolved in THF
(150 mL). After centrifugation and filtration the solvent was removed and
the residue was stirred with five portions of pentane (60 mL). After drying
over sodium sulfate and removal of solvent, a colourless oil (3.1 g,
7.4 mmol, 38%) was obtained. 1H NMR: d 2.40 ± 2.00 (m, 4H), 2.20 (s,
12H), 1.62 (m, 2H), 1.00 (m, Jav 5.5 Hz, 1H).
d) Di(1,1-bis(dimethylaminomethyl)-2-ethyl)mercury(ii): A solution of (1,1-
Bis(dimethylaminomethyl)-2-ethyl)mercuric bromide (4.65 g, 11.0 mmol)
in CH2Cl2 (20 mL) was added to a solution of Na2S2O4 (2.8 g, 16 mmol) in
8% aqueous NaOH (60 mL). After stirring for 20 h, the organic layer was
removed and the water layer was extracted twice with CH2Cl2 (25 mL). The
combined organic layers were dried over CaCl2. After removal of solvent,
molecular distillation (80 ± 908C, 10 5 Torr) gave 1.70 g (3.5 mmol, 63.6%)
of a colourless oil. 1H NMR: d 2.20 (s, 199Hg-H satellites 3J 90 Hz, 16H),
1.30 (m, 1H), 0.81 (m, 2H).
1-Dimethylamino-3-lithiobutane (5)
a) 1-Dimethylamino-3-butanol: 1-Dimethylamino-3-butanone[37] (15.0 g,
0.130 mol) was dissolved in diethyl ether (100 mL) and added dropwise
under stirring at 08C to LiAlH4 (5.7 g, 0.150 mol) in diethyl ether (400 mL).
The mixture was warmed to gentle reflux for 4 h. At 08C, H2O (5 mL) and
15% aqueous NaOH (5 mL), followed by more H2O (15 mL) were
carefully added under stirring. After warming to room temperature the
mixture was dried on MgSO4 and stirred until the organic layer had become
clear. The organic layer was decanted and the residue was washed twice
with diethyl ether (100 mL). The combined organic layers were dried over
Na2SO4 and K2CO3, filtered and concentrated (308C, 500 Torr). The
residue was submitted to distillation and yielded 11.8 g (0.101 mol, 78%) of
a clear oil, b.p. 688C (50 Torr) of high purity. 1H NMR: d 5.27 (brs, OH),
3.93 (q, J 6.0 Hz, 1H), 2.32 ± 2.74 (m, 2H), 2.23 (s, 6H), 1.34 ± 1.69 (m,
2H), 1.13 (d, J 6.0 Hz, 3H).
b) 3-Bromo-1-dimethylaminobutane: At 08C a solution of bromine (16.1 g,
5.17 mL, 0.101 mol) in CH2Cl2 (120 mL) was added dropwise to a stirred
solution of triphenylphosphine (27 g, 0.103 mol) in CH2Cl2 (450 mL). Then
a solution of 1-dimethylamino-3-butanol (11.2 g, 0.096 mol) in CH2Cl2
(120 mL) was added dropwise to the mixture, which was still held at 08C
and stirred. The reaction mixture was slowly warmed (16 h) to room
temperature and was once extracted with H2O (150 mL) and twice with
HCl (0.1m, 150 mL). Pentane (150 mL) was added to the combined water
layers and under strong stirring and cooling at 08C aqueous NaOH (4m)
was added until pH 13 was reached. The organic layer was separated and
aqueous NaOH (4m, 10 mL) was added to the water layer, which was then
extracted twice with pentane (150 mL). The combined organic layers were
dried with MgSO4, filtered and concentrated at 208C and 400 Torr. The
residue was submitted to a short path distillation with solid CO2 as coolant
(258C, 10 3 Torr). Yield: 15.0 g (0.083 mol; 83%) of colourless oil that must
be stored at 808C. 1H NMR: d 4.22 (m, J 6.5 Hz, 1H), 2.38 (q, J
7.0 Hz, CH2N), 2.23 (s, 6H), 1.98 (t, J 7.0 Hz, 2H), 1.74 (d, J 7.0 Hz, 3H).
e) 1,1-Bis(dimethylaminomethyl)-2-lithioethane (4): In an evacuated,
(10 5 Torr) sealed break-seal apparatus, sublimed tert-butyllithium
(4.3 mmol in 2.5 mL pentane) was added under stirring to a solution of
di(1,1-bis(dimethylaminomethyl)-2-ethyl)mercury(ii) (1.04 g, 2.14 mmol) in
pentane (50 mL) at 208C. After 90 min at 08C, the pentane and tBu2Hg
were distilled off (10 5 Torr, room temperature, 2 h). The solid, dark yellow
residue was redissolved in pentane (50 mL) and filtered (P5). At 808C,
tiny colourless crystals formed. The identity of 4 followed from the
products of quenches with Me3SnCl, benzaldehyde and methanol.
(1,1-Bis(dimethylaminomethyl)-2-ethyl)trimethyltin: 1H NMR: d 2.35 ±
1.80 (m, 5H), 2.20 (s, 12H), 0.88 (d, J 6.0 Hz, 2H), 0.33 (s,
J(H,117/119Sn) 49.6/52.0 Hz, 9H); Exact mass: 293.1026 (moleculair ion
minus CH3); calcd (C10H25N2120Sn): 293.1038; MS: m/z (%): 293 (9.8, Sn-
cluster), 165 (5.3, Sn-cluster), 143 (2.1), 98 (24.7), 84 (47.3), 58 (100).
3,3-Bis(dimethylaminomethyl)-1-phenyl-1-propanol: 1H NMR: d 7.45 ±
7.10 (m, 5H), 4.78 (d, J 6.0 Hz, 1H), 2.54 ± 2.07 (m, 5H), 2.27 (s, 12H),
1.87 (m, J' 6.0 Hz, J'' 8.0 Hz, 2H). Exact mass: 250.2050; calcd
(C15H26N2O): 250.2045; MS: m/z(%): 250 (1.2), 207 (6.2), 173 (7.1), 129
(3.7), 105 (2.0), 98 (15.8), 84 (18.6), 79 (14.4), 58 (100).
1,3-Bis(dimethylaminomethyl)-2-methylpropane: 1H NMR: d 2.17 (s,
12H), 2.20 ± 2.10 (m, 2H), 2.00 (dd, J' 8.35 Hz, J'' 11.94 Hz, 2H),
1.87 ± 1.67 (brm, 1H), 0.91 (d, J 6.33 Hz, 3H); Exact mass: 144.1630;
calcd (C8H20N2): 144.1627; MS: m/z (%): 144 (3.0), 99 (64.9), 84 (100), 58
(100).
c) Mixture of 3-dimethylamino-1-methylpropylmercuric bromide and bis(3-
dimethylamino-1-methylpropyl)mercury: Under gentle reflux and stirring a
solution of 3-bromo-1-dimethylaminobutane (5.00 g, 27.8 mmol) in THF
(150 mL) was added dropwise to magnesium shavings (1.5 g, 63 mmol) with
THF (5 mL). The heating was continued for 0.5 h after the addition had
been completed. After cooling to room temperature, the mixture was
titrated (yield 85%) and filtrated. The filtrate was added over 2 h to a
strongly stirred solution of HgBr2 (10.00 g, 27.8 mmol) in THF (100 mL).
After standing for 12 h, the mixture, which contained a white precipitate,
was concentrated and the viscous residue was extracted immediately with
three portions pentane (75 mL). The combined organic layers were dried
with Na2SO4 and concentrated. The residue was a colourless oil which
contained according to 1H NMR 3-dimethylamino-1-methylpropylmercu-
ric bromide and bis(3-dimethylamino-1-methylpropyl)-mercury in a molar
ratio of 93.5:6.5, total yield: 5.81 g (Æ 15.3 mmol, 55%). 1H NMR:
3-dimethylamino-1-methylpropylmercuric bromide: d 1.61 ± 2.56 (m,
At low temperatures, both 1H and 13C NMR spectra of 4 in toluene indicate
the presence of at least two species (A,B) whose ratio (1:1) is independent
of concentration. The proton-decoupled 13C NMR signal of the a-carbon
atom (Ca) is of such broadness that its multiplicity could not be discerned.
A rough measure of the 13C,6,7Li cou-
pling
constants
was
obtained:
J(13C,6Li) ꢀ 5(Æ0.5) Hz (see Figure 6),
J(13C,7Li) ꢀ 14(Æ1.0) Hz). At 183 K,
three sharp 6Li resonances occur at
d 2.51, 2.23 and 1.95. These are
strongly broadened at 273 K and coa-
lesce at 295 K (d 2.11). Coalescence
at higher temperatures is also ob-
5H), 2.20 (s, 6H), 1.42 (d, J 7.0 Hz, 3H, 199Hg-H satellites J(199Hg,H)
3
288 Hz); 1H NMR: bis(3-dimethylamino-1-methylpropyl)mercury: d
1.61 ± 2.56 (m, 10H), 2.18 (s, 12H), 1.24 (brs, 6H, 3J(199 Hg,H) can not
be given because of the low intensity of the signal).
d) (3-Dimethylamino-1-methylpropyl)-tert-butylmercury: Over a period of
15 min tert-butyllithium (10.5 mL, 1.49m, 15.6 mmol) was added dropwise
to a cooled ( 128C) and stirred solution of 3-dimethylamino-1-methyl-
propylmercuric bromide (5.41 g, ca. 13.3 mmol) and bis(3-dimethylamino-
1-methylpropyl)mercury (see above) (0.9 mmol) in pentane (800 mL).
[Bis(3-dimethylamino-1-methylpropyl)mercury reacts with tert-butyllithi-
um to give 5 and (3-dimethylamino-1-methylpropyl)-tert-butylmercury as
products, of which 5 is hydrolyzed during work up]. Cooling and stirring
were continued for 1.5 h. Then methanol (0.56 mL) was added and the
mixture was warmed to room temperature. Then it was centrifuged and the
1
served for H and 13C NMR signals.
Li-CaH2aCbHb(Cc'H2c'NMe2)CcH2cNMe2 :
1H NMR ([D8]toluene, 187 K): Ha:
d 1.333, 0.914 (dd, Jav 8.8 Hz);
Hc (or Hc'): d 2.832 (dd, Jav
Figure 6. 13C NMR trace of
C-a of [6Li]4.
9.0 Hz); NMe2: d 2.213 (A), 2.180
(A), 2.168 (B), 2.153 (A), 2.096 (B);
Chem. Eur. J. 2000, 6, No. 2
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