10.1002/ejoc.202000309
European Journal of Organic Chemistry
FULL PAPER
13C-NMR spectra were recorded at 23°C on a Bruker Ultrashield 300
spectrometer operating at 300.36 MHz (1H) and 75.53 MHz (13C).
Deuterated solvents were purchased from Cambridge Isotope
Laboratories.
3-(2-Methyl-1H-imidazol-1-yl)propanenitrile (2A): Acrylonitrile (0.9 mL,
0.0136 mol, 1.2 eq.) was added to imidazole (1.034 g, 0.0126 mol, 1.0 eq.)
in a 10 mL Schlenk tube. The tube was sealed and the suspension was
heated up to 80 °C under constant stirring whereupon dissolution of
imidazole occurred within approx. 20 min. After 3 h the reaction mixture
was cooled to room temperature and the resulting colourless oil was dried
under reduced pressure. The magnetic stirrer bar was removed from the
product. Yield: 1.69 g, (0.00125 mol), 99.0 % o. Th., colourless oil.
Analytical data in accordance with literature.[22] 1H-NMR (300 MHz, CDCl3)
δ = 6.97, 6.90 (s, 2H, M.Im4,5), 4.17 (t, J = 6.7 Hz, 2H, N-CH2CH2-CN),
2.75 (t, J = 6.7 Hz, 2H, N-CH2CH2-CN), 2.43 (s, 3H, Me) ppm. 13C{1H}-
NMR (75 MHz, CDCl3) δ = 144.5 (M.Im2), 128.5, 118.8 (CH, M.Im4,5), 116.6
(CN), 41.6 (CH2), 20.1 (CH2), 13.1 (CH3, Me) ppm.
3-(1H-Imidazol-1-yl)propanenitrile
(1A):
Acrylonitrile
(0.9 mL,
0.0136 mol, 1.2 eq.) was added to imidazole (0.912 g, 0.0134 mol, 1.0 eq.)
in a 10 mL Schlenk tube. The tube was sealed and the suspension was
heated up to 80 °C under constant stirring whereupon dissolution of
imidazole occurred within approx. 20 min. After 3 h the reaction mixture
was cooled to room temperature and the resulting colorless oil was dried
under reduced pressure (to get rid of the excess of acrylonitrile). The
magnetic stirrer bar was removed from the product. Yield: 1.61 g,
(0.00133 mol), 98.0 % o. Th., colorless oil. Analytical data in accordance
with literature.[22] 1H-NMR (300 MHz, CDCl3) δ = 7.58, 7.12, 7.02 (s, 3H,
Im2,4,5), 4.27 (t, J = 6.5 Hz, 2H, N-CH2CH2-CN), 2.81 (t, J = 6.6 Hz, 2H, N-
CH2CH2-CN) ppm. 13C{1H}-NMR (75 MHz, CDCl3) δ = 137.1 (CH, Im2),
130.6, 118.7 (CH, Im4,5), 116.6 (CN), 42.6 (CH2), 20.8 (CH2) ppm.
Methyl 3-(2-methyl-1H-imidazol-1-yl)propanoate (2B): Methyl acrylate
(3.3 mL, 0.0364 mol, 1.2 eq.) was added to 2-methylimidazole (2.487 g,
0.0303 mol, 1.0 eq.) in a 15 mL Schlenk tube. The tube was sealed and
the suspension was heated up to 80 °C under constant stirring whereupon
dissolution of 2-methylimidazole occurred within approx. 5 min. After 6 h
the reaction mixture was cooled to room temperature and the resulting oil
was dried under reduced pressure whereupon the colourless oil solidified.
The magnetic stirrer bar was removed from the product. Yield: 4.97 g,
(0.0295 mol), 97.5 % o. Th., colorless powder. Analytical data in
accordance with literature.[20,23] 1H-NMR (300 MHz, CDCl3) δ = 6.91, 6.85
(s, 2H, Im4,5), 4.17 (t, J = 6.8 Hz, 2H, N-CH2CH2-COO), 3.70 (s, 3H, COO-
CH3), 2.75 (t, J = 6.8 Hz, 2H, N-CH2CH2-COO), 2.41 (s, 3H, Me) ppm.
13C{1H}-NMR (75 MHz, CDCl3) δ = 170.9 (COO), 144.6 (Im2), 127.7 (CH,
Im4), 119.0 (CH, Im5), 52.2 (CH3, Me), 41.4 (CH2), 35.3 (CH2), 13.1 (CH3,
Me) ppm.
Methyl 3-(1H-imidazol-1-yl)propanoate (1B): Methyl acrylate (3.6 mL,
0.0392 mol, 1.2 eq.) was added to imidazole (2.224 g, 0.0327 mol, 1.0 eq.)
in a 10 mL Schlenk tube. The tube was sealed and the suspension was
heated up to 80 °C under constant stirring whereupon dissolution of
imidazole occurred within approx. 3 min. After 5 h the reaction mixture was
cooled to room temperature and the resulting oil was dried under reduced
pressure (to get rid of the excess of methyl acrylate) whereupon the
yellowish oil solidified. The magnetic stirrer bar was removed from the
product. Yield: 4.94 g, (0.0320 mol), 98.0 % o. Th., colorless powder.
Analytical data in accordance with literature.[20,23] 1H-NMR (300 MHz,
CDCl3) δ = 7.50 (s, 1H, Im2), 7.03, 6.92 (s, 2H, Im4,5), 4.26 (t, J = 6.5 Hz,
2H, N-CH2CH2-COO), 3.68 (s, 3H, COO-CH3), 2.77 (t, J = 6.6 Hz, 2H, N-
CH2CH2-COO) ppm. 13C{1H}-NMR (75 MHz, CDCl3) δ = 171.0 (COO),
137.4 (CH, Im2), 129.8, 118.9 (CH, Im4,5), 52.2 (CH3, Me), 42.4 (CH2), 35.9
(CH2) ppm.
Methyl 3-(2-methyl-1H-imidazol-1-yl)butanoate (2C): Methyl crotonate
(1.66 mL, 0.0156 mol, 1.2 eq.) was added to 2-methylimidazole (1.072 g,
0.0131 mol, 1.0 eq.) in a 10 mL Schlenk tube. The tube was sealed and
the suspension was heated up to 80 °C under constant stirring whereupon
dissolution of 2-methylimidazole occurred within approx. 5 min. After 24 h
the reaction mixture was cooled to room temperature and the resulting
brown oil was dried under reduced pressure. The magnetic stirrer bar was
removed from the product. Yield: 2.35 g, (0.0129 mol), 98.5 % o. Th.,
brownish oil. Analytical data in accordance with literature.[22,24] 1H-NMR
(300 MHz, CDCl3) δ = 6.93, 6.84 (s, 2H, M.Im4,5),4.71–4.60 (m, J = 7.1 Hz,
1H, N-CH(CH3)-CH2), 3.63 (s, 3H, COO-CH3), 2.73 (m, J = 6.7 Hz, 2H,
N-CH(CH3)CH2-COO), 2.42 (s, 3H, Me) 1.46-1.44 (d, J = 6.8 Hz, 3H,
N-CH(CH3)-CH2) ppm. 13C{1H}-NMR (75 MHz, CDCl3) δ = 170.5 (COO),
144.2 (M.Im2), 127.8, 114.6 (CH, M.Im4,5), 52.0 (CH3, COO-CH3), 48.3 (CH,
N-CH(CH3 )-CH2), 41.9 (CH2, N-CH(CH3)-CH2), 21.8 (CH3, N-CH(CH3)-
CH2), 13.1 (CH3, Me) ppm.
Methyl 3-(1H-imidazol-1-yl)butanoate (1C): Methyl crotonate (1.56 mL,
0.0147 mol, 1.2 eq.) was added to imidazole (0.856 g, 0.0123 mol, 1.0 eq.)
in a 10 mL Schlenk tube. The tube was sealed and the suspension was
heated up to 80 °C under constant stirring whereupon dissolution of
imidazole occurred within approx. 30 min. After 24 h the reaction mixture
was cooled to room temperature and the resulting oil was dried under
reduced pressure. The magnetic stirrer bar was removed from the product.
Yield: 2.02 g, (0.0120 mol), 97.5 % o. Th., slightly yellow oil. Analytical data
in accordance with literature.[24] 1H-NMR (300 MHz, CDCl3) δ = 7.54, 7.05,
6.94 (s, 3H, Im2,4,5), 4.76–4.65 (m, J = 6.9 Hz, 1H, N-CH(CH3)-CH2), 3.64
(s, 3H, COO-CH3), 2.74 (m, J = 6.4 Hz, 2H, N-CHCH2-COO), 1.55-1.53 (d,
J = 6.8 Hz, 3H, N-CH(CH3)-CH2) ppm. 13C{1H}-NMR (75 MHz, CDCl3) δ =
170.5 (COO), 135.9 (CH, Im2), 129.6, 116.5 (CH, Im4,5), 52.1 (CH,
N-CH(CH3)-CH2), 50.1 (CH3, Me), 42.6 (CH2, N-CH(CH3)-CH2), 21.7 (CH3,
N-CH(CH3)-CH2) ppm.
Methyl
2-methyl-3-(2-methyl-1H-imidazol-1-yl)propanoate
(2D):
Methyl methacrylate (2.00 mL, 0.018 mol, 1.2 eq.) was added to 2-
methylimidazole (1.280 g, 0.0156 mol, 1.0 eq.) in a 15 mL Schlenk tube.
The tube was sealed and the suspension was heated up to 80 °C under
constant stirring whereupon dissolution of 2-methylimidazole occurred
within approx. 60 min. After 24 h the reaction mixture was cooled to room
temperature and the resulting oil was dried under reduced pressure. The
magnetic stirrer bar was removed from the product. Yield: 2.79 g,
(0.0153 mol), 98.0 % o. Th., yellow oil. Analytical data in accordance with
literature.[22] 1H-NMR (300 MHz, CDCl3) δ = 6.89, 6.79 (s, 2H, M.Im4,5),
4.20–3.83 (m, 2H, N-CH2-CH(CH3)-COO), 3.66 (s, 3H, COO-CH3), 2.89–
2.82 (m, J = 7.2 Hz, 1H, N-CH2-CH(CH3)-COO), 2.38 (s, 3H, Me),
1.20-1.18 (d, 3H, N- CH2-CH(CH3)-COO) ppm. 13C{1H}-NMR (75 MHz,
CDCl3) δ = 174.3 (COO), 144.7 (M.Im2), 127.5, 119.4 (CH, M.Im4,5), 52.2
(CH2, N- CH2-CH(CH3)-COO), 48.4 (CH3, COO-CH3), 41.1
(N- CH2-CH(CH3)-COO), 15.1, 13.1 (CH3, Me) ppm.
Methyl
3-(1H-imidazol-1-yl)-2-methylpropanoate
(1D):
Methyl
methacrylate (2.66 mL, 0.0250 mol, 1.2 eq.) was added to imidazole
(1.416 g, 0.0208 mol, 1.0 eq.) in a 15 mL Schlenk tube. The tube was
sealed and the suspension was heated up to 80 °C under constant stirring
whereupon dissolution of imidazole occurred within approx. 50 min. After
24 h the reaction mixture was cooled to room temperature and the
resulting oil was dried under reduced pressure. The magnetic stirrer bar
was removed from the product. Yield: 3.43 g, (0.0204 mol), 98.0 % o. Th.,
slightly yellow oil. Analytical data in accordance with literature.[22] 1H-NMR
(300 MHz, CDCl3) δ = 7.46, 7.04, 6.88 (s, 3H, Im2,4,5), 4.28–3.97 (m, 2H,
N- CH2-CH(CH3)-COO, 3.67 (s, 3H, COO-CH3), 2.91–2.84 (m, J = 6.8 Hz,
1H, N-CH2-CH(CH3)-COO), 1.19-1.18 (d, 3H, N-CH2-CH(CH3)-COO) ppm.
13C{1H}-NMR (75 MHz, CDCl3) δ = 174.3 (COO), 137.7 (CH, Im2), 129.7,
119.3 (CH, Im4,5), 52.3 (CH2, N-CH2-CH(CH3)-COO), 49.4 (CH3, COO-
CH3), 41.5 (N-CH2-CH(CH3)-COO), 15.0 (CH3 N-CH2-CH(CH3)-COO) ppm.
Methyl 3-(1H-1,2,4-triazol-1-yl)propanoate (3B): Methyl acrylate (1.7 mL,
0.0188 mol, 1.2 eq.) was added to 1,2,4-triazole (1.053 g, 0.0152 mol,
1.0 eq.) in a 10 mL Schlenk tube. The tube was sealed and the suspension
was heated up to 80 °C under constant stirring whereupon dissolution of
4
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