Organometallics
Article
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atmosphere using standard Schlenk or glovebox techniques. H and
13C NMR spectra were recorded on a 400 MHz spectrometer. Carbon,
hydrogen, and nitrogen analyses were performed by direct combustion
with an EA-1110 instrument. The FT-IR spectra were recorded with a
FT-IR spectrometer as KBr pellets. X-ray crystallographic data were
collected using an AXS D8 X-ray diffractometer. Toluene and hexane
were freshly distilled by refluxing over sodium/benzophenone ketyl
and distilled prior to use. PhCl, C6D6, PhCl-d5 and PhBr-d5 were
degassed and distilled over CaH2. Zr[N(CH3)2]4 and Ti[N(CH3)2]4
are commercially available and were used as received from Acros.
Amines were distilled over CaH2. Alkynes were degassed, flushed with
argon, and stored over molecular sieves (4 Å). The ligand precursor A
was prepared according to reported procedures.14
(0.20 g, 0.99 mmol). H NMR (400 MHz, CDCl3): δ 7.37−7.28 (m,
4H, ArH), 7.23−7.20 (m, 1H, ArH), 7.08 (t, 2H, ArH), 6.63 (t, 2H,
ArH), 6.50 (d, 2H, ArH), 4.49−4.44 (q, 1H, CH), 4.02 (s, 1H, NH),
1.50 (d, 3H, J = 6.72 Hz, CHCH3). 13C{1H} NMR (100 MHz,
CDCl3): 147.4, 145.4, 129.3, 128.8, 127.1, 126.0, 117.4, 113.5 (Ar−C),
53.6 (CH), 25.2 (CH3).
N-(1-(p-Tolyl)ethyl)aniline (5b). 5b was prepared from 3a (0.091
mL, 1 mmol) and 4b (0.187 mL, 1.5 mmol) as a colorless oil in 98%
yield (0.21 g, 0.98 mmol). 1H NMR (400 MHz, CDCl3): δ 7.25−7.23
(m, 2H, ArH), 7.12−7.06 (m, 4H, ArH), 6.64−6.61 (m, 1H, ArH),
6.51−6.49 (m, 2H, ArH), 4.47−4.42 (q, 1H, CH), 3.96 (s, 1H, NH),
2.31 (s, 3H, ArCH3), 1.48 (d, 3H, J = 6.72 Hz, CH3). 13C{1H} NMR
(100 MHz, CDCl3): 147.6, 142.5, 136.6, 129.6, 129.4, 126.0, 117.4,
113.5 (ArC), 53.4 (CH), 25.3 (ArCH3), 21.4 (CH3).
Preparation of Zr[N(CH3)2]2[ONNO] (1). To a solution of
Zr[N(CH3)2]4 (0.80 g, 3 mmol) in toluene (10 mL) was added
dropwise A (1.57 g, 3 mmol) in toluene (5 mL) at room temperature
over 15 min. After the mxture was stirred for 12 h, toluene was
removed under reduced pressure and hexane (5 mL) was added.
Complex 1 was obtained as a colorless solid after the hexane solution
was cooled to −30 °C (1.90 g, 2.7 mmol, 90%). Crystals suitable for X-
ray diffraction analyses were grown from hexane solution at −30 °C.
IR (neat): ν 2955, 2900, 2869, 1478, 1387, 1360, 1302, 1274, 1239,
1203, 1168, 1132, 1026, 842, 806, 760, 729, 606 cm−1. 1H NMR (400
MHz, C6D6): δ 7.64 (s, 2H, ArH), 7.09 (s, 2H, ArH), 4.30 (d, 2H, J =
13.1 Hz, ArCH2), 3.47 (s, 6H, N(CH3)2), 3.23 (s, 6H, N(CH3)2), 2.91
(d, 1H, J = 13.1 Hz, ArCH2), 2.24 (m, 2H, NCH2C), 1.76 (s, 18H, o-
C(CH3)3), 1.74 (s, 6H, N(CH3)2), 1.58 (s, 2H, CCH2N), 1.43 (s,
18H, p-C(CH3)3). 13C{1H} NMR (100 MHz, C6D6): 158.5, 139.4,
136.5, 125.9, 125.2, 124.7 (ArC), 65.6 (ArCH2N), 60.2 (ArCH2N),
50.4 (NCH2CH2N), 48.0 (NCH2CH2N), 46.6 (N(CH3)2), 44.7
(N(CH3)2), 35.4 (C(CH3)3), 34.2 (C(CH3)3), 32.0 (C(CH3)3), 30.7
(C(CH3)3). Anal. Calcd for C38H66N4O2Zr: C, 65.00; H, 9.47; N, 7.98.
Found: C, 65.02; H, 9.43; N, 7.96.
Preparation of Ti[N(CH3)2]2[ONNO] (2). To a solution of
Ti[N(CH3)2]4 (0.67 g, 3 mmol) in toluene (10 mL) was added
dropwise A (1.57 g, 3 mmol) in toluene (5 mL) at room temperature
over 15 min. After the mixture was stirred for 12 h, toluene was
removed under reduced pressure and hexane (5 mL) was added.
Complex 2 was obtained as a colorless solid after the hexane solution
was cooled to −30 °C (1.78 g, 2.7 mmol, 90%). IR (neat): ν 2955,
2901, 2869, 1478, 1388, 1361, 1274, 1238, 1203, 1168, 1132, 876, 842,
760, 728 cm−1. 1H NMR (400 MHz, C6D6): δ 7.64 (s, 2H, ArH), 7.09
(s, 2H, ArH), 4.05 (d, 2H, J = 13.1 Hz, ArCH2), 3.65 (s, 6H,
N(CH3)2), 3.37 (s, 6H, N(CH3)2), 2.90 (d, 2H, J = 13.1 Hz, ArCH2),
2.24 (t, 2H, NCH2C), 1.80 (s, 18H, C(CH3)3), 1.79 (s, 6H, o-
N(CH3)2), 1.59 (t, 2H, CCH2N), 1.43 (s, 18H, p-C(CH3)3). 13C{1H}
NMR (100 MHz, C6D6): 159.9, 139.3, 135.8, 126.0, 125.0, 124.4
(ArC), 66.6 (ArCH2N), 60.5 (ArCH2N), 52.1 (NCH2CH2N), 51.0
(NCH2CH2N), 48.8 (N(CH3)2), 48.8 (N(CH3)2), 35.6 (C(CH3)3),
34.2 (C(CH3)3), 31.9 (C(CH3)3), 31.0 (C(CH3)3). Anal. Calcd for
C38H66N4O2Ti: C, 69.28; H, 10.10; N, 8.50. Found: C, 69.30; H,
10.10; N, 8.49.
General Procedure for Hydroamination Reactions. In a
glovebox filled with nitrogen, a PhCl solution (1 mL) of [Ph3C][B-
(C6F5)4] (0.092 g, 0.01 mmol) was added to a PhCl solution (1 mL)
of 1 (0.070 g, 0.01 mmol) with stirring. A color change from orange to
colorless was observed immediately. After 5 min, 3 (1 mmol) and 4
(1.5 mmol) were added to the mixture successively. The resulting
solution was stirred at 120 °C for the desired time. After the mixture
was cooled to 0 °C, LiAlH4 (76 mg, 2 mmol) was added, and the
resulting mixture was stirred at 60 °C for 2 h. The reaction was
quenched by an aqueous solution of NaOH (6 M). The product was
extracted with toluene (3 × 1 mL). The crude product obtained after
removal of solvent was analyzed by GC (with n-hexadecane as internal
standard) to determine the yield. All amines shown in Tables 1−5
were isolated by column chromatography (petroleum ether/ethyl
acetate 100/1, Al2O3) as viscous colorless oils and characterized by 1H
and 13C NMR spectroscopy.
N-(1-(4-Fluorophenyl)ethyl)aniline (5c). 5c was prepared from 3a
(0.091 mL, 1 mmol) and 4c (0.172 mL, 1.5 mmol) as a colorless oil in
97% yield (0.21 g, 0.97 mmol). 1H NMR (400 MHz, CDCl3): δ 7.22−
7.18 (m, 2H, ArH), 7.01−6.97 (m, 2H, ArH), 6.90−6.85 (m, 2H,
ArH), 6.57−6.53 (m, 1H, ArH), 6.39−6.37 (m, 2H, ArH), 4.37−4.32
(q, 1H, CH), 3.88 (s, 1H, NH), 1.37−1.35 (d, 3H, J = 6.72 Hz, CH3).
13C{1H} NMR (100 MHz, CDCl3): 163.2, 160.7, 147.3, 141.1, 129.3,
127.5, 117.6, 115.5, 113.5 (ArC), 53.05 (CH), 25.39 (CH3).
N-(1-(2-Fluorophenyl)ethyl)aniline (5d). 5d was prepared from 3a
(0.091 mL, 1 mmol) and 4d (0.172 mL, 1.5 mmol) as a colorless oil in
93% yield (0.20 g, 0.93 mmol). 1H NMR (400 MHz, CDCl3): δ 7.37−
7.33 (m, 2H, ArH), 7.19−6.14 (m, 1H, ArH), 7.11−7.07 (m, 2H,
ArH), 7.05−7.00 (m, 2H, ArH), 6.67−6.63 (m, 1H, ArH), 6.52−6.50
(m, 2H, ArH), 4.83−4.78 (q, 1H, CH), 4.01 (s, 1H, NH), 1.52−1.51
(d, 3H, J = 6.72 Hz, CH3). 13C{1H} NMR (100 MHz, CDCl3): 161.8,
159.3, 131.9, 131.7, 129.2, 128.4, 127.3, 127.2, 124.5, 124.4, 117.6,
115.6, 115.4, 113.3 (ArC), 47.5 (CH), 23.4 (CH3).
N-(1-(m-Tolyl)ethyl)aniline (5e). 5e was prepared from 3a (0.091
mL, 1 mmol) and 4e (0.187 mL, 1.5 mmol) as a colorless oil in 95%
yield (0.20 g, 0.95 mmol). 1H NMR (400 MHz, CDCl3): δ 7.13−7.09
(m, 3H, ArH), 7.02−6.99 (m, 2H, ArH), 6.96−6.94 (m, 1H, ArH),
6.57−6.54 (m, 1H, ArH), 6.44−6.42 (m, 2H, ArH), 4.37−4.33 (q, 1H,
CH), 3.91 (s, 1H, NH), 2.24 (s, 3H, ArCH3), 1.41−1.40 (d, 3H, J =
6.72 Hz, CH3). 13C{1H} NMR (100 MHz, CDCl3): 147.6, 145.4,
138.4, 129.3, 128.7, 127.9, 126.7, 123.1, 117.4, 113.5 (ArC), 53.6
(CH), 25.2 (ArCH3), 21.8 (CH3).
N-(1-(3-Bromophenyl)ethyl)aniline (5f). 5f was prepared from 3a
(0.091 mL, 1 mmol) and 4f (0.181 mL, 1.5 mmol) as a colorless oil in
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97% yield (0.27 g, 0.97 mmol). H NMR (400 MHz, CDCl3): δ 7.53
(s, 1H, ArH), 7.36−7.35 (m, 1H, ArH), 7.31−7.29 (m, 1H, ArH),
7.20−7.16 (m, 1H, ArH), 7.13−7.09 (m, 2H, ArH), 6.69−6.66 (m,
1H, ArH), 6.50−6.48 (m, 2H, ArH), 4.45−4.40 (q, 1H, CH), 4.01 (s,
1H, NH), 1.50−1.48 (d, 3H, J = 6.72 Hz, CH3). 13C{1H} NMR (100
MHz, CDCl3): 147.0, 130.1, 129.2, 128.7, 127.9, 126.7 123.1, 117.4,
113.5 (ArC), 53.3 (CH), 25.2 (CH3).
N-(1-(Thiophen-2-yl)ethyl)aniline (5g). 5g was prepared from 3a
(0.091 mL, 1 mmol) and 4g (0.150 mL, 1.5 mmol) as a colorless oil in
93% yield (0.19 g, 0.93 mmol). 1H NMR (400 MHz, CDCl3): δ 7.08−
7.05 (m, 3H, ArH), 6.89−6.84 (m, 2H, ArH), 6.64−6.60 (m,1H,
ArH), 6.55−6.53 (m, 2H, ArH), 4.76−4.71 (q, 1H, CH), 3.58 (s, 1H,
NH), 1.54−1.53 (d, 3H, J = 6.72 Hz, CH3). 13C{1H} NMR (100
MHz, CDCl3): 150.5, 147.3, 129.8, 129.3, 126.9, 124.2, 123.7, 123.6,
123.1, 118.3, 118.0, 114.0, 113.7 (ArC), 49.7 (CH), 25.2, 24.7 (CH3).
N-(1-Phenylpropan-2-yl)aniline (5h). 5h was prepared from 3a
(0.091 mL, 1 mmol) and 4h (0.17 g, 1.5 mmol) as a colorless oil in
96% yield (0.20 g, 0.96 mmol). 1H NMR (400 MHz, CDCl3): δ 7.21−
7.17 (m, 2H, ArH), 7.13−7.07 (m, 5H, ArH), 6.62−6.58 (m, 1H,
ArH), 6.53−6.51 (m, 2H, ArH), 3.70−3.62 (m, 1H, CH), 3.35 (s, 1H,
NH), 2.85−2.81 (m, 1H, ArCH2), 2.61−2.56 (m, 1H, ArCH2), 1.05−
1.03 (d, 3H, J = 6.72 Hz, CH3). 13C{1H} NMR (100 MHz, CDCl3):
147.5, 138.9, 129.8, 129.7, 128.6, 126.6, 117.6, 113.7 (ArC), 49.6
(CH), 42.5 (ArCH2), 20.4 (CH3).
N-(1-Cyclohexylethyl)aniline (5i). 5i was prepared from 3a (0.091
mL, 1 mmol) and 4i (0.196 mL, 1.5 mmol) as a colorless oil in 97%
yield (0.20 g, 0.97 mmol). 1H NMR (400 MHz, CDCl3): δ 7.25−7.12
(m, 2H), 6.65−6.61 (m, 1H, ArH), 6.57−6.55 (m, 2H, ArH), 3.47 (s,
N-(1-Phenylethyl)aniline (5a). 5a was prepared from 3a (0.091 mL,
1 mmol) and 4a (0.165 mL, 1.5 mmol) as a colorless oil in 99% yield
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dx.doi.org/10.1021/om401158a | Organometallics 2014, 33, 994−1001