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R. Ottria et al. / Chemistry and Physics of Lipids 165 (2012) 705–711
3-CH2), 2.34 (2H, t, J = 6.8, 2-CH2), 3.42 (2H, dt, J = 4.8, 5.0,
2ꢀ-CH2), 4.16 (2H, t, J = 5.0, 1ꢀ-CH2), 4.77 (1H, bs, NH).
Calcd for C22H42F3NO4 (441.57): C, 59.84; H, 9.59; N, 3.17. Found:
C, 59.98; H, 9.45; N, 3.21.
2.4.2.4. 5d. 1H NMR ı: 0.90 (3H, J = t, 6.8, 18-CH3), 1.24–1.36 (20
H, m, 4–7 and 12–17 CH2), 1.47 (9H, s, C(CH3)3), 1.61–1.68
(2H, m, 3-CH2), 2.01–2.05 (4H, m, 8- and 11-CH2), 2.35 (2H,
t, J = 7.2, 2-CH2), 3.41 (2H, dt, J = 4.8, 4.8, 2ꢀ-CH2), 4.15 (2H, t,
J = 4.8, 1ꢀ-CH2), 4.79 (1H, bs, NH), 5.33–5.40 (2H, m, 9- and
10-CH).
2.4.7. O-oleoylethanolamine-N-trifluoroacetate salt (2d)
The title compound 2d was obtained from oleic acid as
amorphous solid; isolated overall yield 58.7 mg (89%). Rf 0.20
(CH2Cl2/MeOH 95:5). 1H NMR ı: 0.90 (3H, J = t, 6.8, 18-CH3),
1.25–1.37 (20 H, m, 4–7 and 12–17 CH2), 1.59–1.66 (2H, m, 3-CH2),
2.04–2.08 (4H, m, 8- and 11-CH2), 2.38 (2H, t, J = 7.4, 2-CH2), 3.26
(2H, bt, J = 5.5 2ꢀ-CH2), 4.37 (2H, bt, J = 5.5, 1ꢀ-CH2), 5.35–5.41 (2H,
2.4.2.5. 5e. 1H NMR ı: 0.91 (3H, t, J = 7.0, 18-CH3), 1.30–1.39 (14
H, m, 4–7 and 15–17 CH2), 1.46 (9H, s, C(CH3)3), 1.59–1.67
(2H, m, 3-CH2), 2.08 (4H, dt, J = 6.9, 6.9, 8-CH2 and 14-CH2),
2.33 (2H, t, J = 7.6, 2-CH2), 2.79 (2H, t, J = 6.2, 11-CH2), 3.41
(2H, dt, J = 4.8, 5.0, 2ꢀ-CH2), 4.15 (2H, t, J = 5.0, 1ꢀ-CH2), 4.78
(1H, bs, NH), 5.32–5.43 (4H, m, 9- 10- 12- and 13-CH).
2.4.2.6. 5f. 1H NMR ı: 1.00 (3H, t, J = 6.9, 18-CH3), 1.31–1.39 (8H, m,
4–7 CH2), 1.47 (9H, s, C(CH3)3), 1.62–1.67 (2H, m, 3-CH2),
2.06–2.13 (4H, m, 8-CH2 and 17-CH2), 2.34 (2H, t, J = 7.6,
2-CH2), 2.81–2.84 (4H, m, 11- and 14-CH2), 3.41 (2H, dt,
J = 4.9, 4.7, 2ꢀ-CH2), 4.15 (2H, t, J = 4.9, 1ꢀ-CH2), 4.77 (1H, bs,
NH), 5.31–5.45 (6H, m, 9- 10- 12- 13- 15- and 16-CH).
2.4.2.7. 5g. 1H NMR ı: 1.00 (3H, t, J = 7.4, 20-CH3), 1.47 (9H, s,
C(CH3)3), 1.73 (2H, tt, J = 6.9, 7.6, 3-CH2), 2.10 (2H, dq, J = 7.6,
7.6, 19-CH2), 2.13 (2H, dt, J = 6.9, 7.6, 4-CH2), 2.35 (2H, t,
J = 7.6, 2-CH2), 2.82–2.88 (8H, m, 7- 10- 13- and 16-CH2),
3.41 (2H, dt, J = 5.0, 5.0, 2ꢀ-CH2), 4.15 (2H, t, J = 4.9, 1ꢀ-CH2),
4.78 (1H, bs, NH),5.32–5.45 (10H, m, 5- 6- 8- 9- 11- 12- 14-
15- 17- and 18-CH).
+
m, 9- and 10-CH), the NH3 signal was too broad to be detected.
Anal. Calcd for C22H40F3NO4 (439.55): C, 60.11; H, 9.17; N, 3.19.
Found: C, 60.21; H, 9.25; N, 3.16.
2.4.8. O-linoleylethanolamine-N-trifluoroacetate salt (2e)
The title compound 2e was obtained from linoleic acid as colour-
less oil; isolated overall yield 53.2 mg (81%). Rf 0.18 (CH2Cl2/MeOH
95:5). 1H NMR ı: 0.91 (3H, t, J = 7.0, 18-CH3), 1.28–1.39 (14 H, m,
4–7 and 15–17 CH2), 1.59–1.67 (2H, m, 3-CH2), 2.07 (4H, dt, J = 6.4,
7.6, 8-CH2 and 14-CH2), 2.36 (2H, t, J = 7.4, 2-CH2), 2.79 (2H, t, J = 6.7,
11-CH2), 3.27 (2H, bt, J = 5.5, 2ꢀ-CH2), 4.36 (2H, bt, J = 5.5, 1ꢀ-CH2),
+
5.32–5.43 (4H, m, 9- 10- 12- and 13-CH), the NH3 signal was
too broad to be detected. Anal. Calcd for C22H38F3NO4 (437.54):
C, 60.39; H, 8.75; N, 3.20. Found: C, 60.51; H, 8.85; N, 3.22.
2.4.9. O-˛-linolenylethanolamine-N-trifluoroacetate salt (2f)
The title compound 2f was obtained from ␣-linolenic acid
as colourless oil; isolated overall yield 52.3 mg (80%). Rf 0.16
(CH2Cl2/MeOH 95:5). 1H NMR ı: 0.99 (3H, t, J = 7.0, 18-CH3),
1.30–1.38 (8H, m, 4–7 CH2), 1.59–1.65 (2H, m, 3-CH2), 2.05–2.13
(4H, m, 8-CH2 and 17-CH2), 2.37 (2H, t, J = 7.6, 2-CH2), 2.82–2.84
(4H, m, 11- and 14-CH2), 3.27 (2H, bt, J = 4.9, 2ꢀ-CH2), 4.37 (2H,
bt, J = 4.9, 1ꢀ-CH2), 5.31–5.44 (6H, m, 9- 10- 12- 13- 15- and 16-
2.4.3. Deprotection of compounds 5a–5g. General method
The appropriate crude Boc-derivative (0.15 mmol) was dis-
solved in TFA 5% in CH2Cl2 (3 ml) and stirred overnight. The solvent
was removed and crude was purified by column chromatography
(CH2Cl2/MeOH 95:5 containing 0.5% TFA) to give the desired com-
pound.
+
CH), the NH3 signal was too broad to be detected. Anal. Calcd for
C22H36F3NO4 (435.52): C, 60.67; H, 8.33; N, 3.22. Found: C, 60.79;
H, 8.25; N, 3.14.
2.4.4. O-arachidonoylethanolamine-N-trifluoroacetate salt (2a)
The title compound 2a was obtained from arachidonic acid
as colourless oil; isolated overall yield 55.4 mg (80%). Rf 0.18
(CH2Cl2/MeOH 95:5). NMR ı: 0.91 (3H, t, J = 7.4, 20-CH3), 1.26–1.39
(6 H, m, 17–19 CH2), 1.70 (2H, tt, J = 7.0, 7.6, 3-CH2), 2.07 (2H, dq,
J = 7.6, 7.6, 16-CH2), 2.14 (2H, dt, J = 7.0, 7.4, 4-CH2), 2.39 (2H, t,
J = 7.0, 2-CH2), 2.81–2.87 (6H, m, 7- 10- and 13-CH2), 3.29 (2H, bt,
J = 5.0, 2ꢀ-CH2), 4.37 (2H, bt, J = 5.0, 1ꢀ-CH2), 5.33–5.45 (8H, m, 5- 6-
2.4.10. O-eicosapentaenoylethanolamine-N-trifluoroacetate
salt (2g)
The title compound 2g was obtained from eicosapentaenoic
acid as colourless oil; isolated overall yield 53.8 mg (78%). Rf 0.19
(CH2Cl2/MeOH 95:5). 1H NMR ı: 1.00 (3H, t, J = 7.0, 20-CH3), 1.73
(2H, tt, J = 6.9, 7.6, 3-CH2), 2.10 (2H, dq, J = 7.6, 7.6, 19-CH2), 2.14
(2H, dt, J = 6.9, 7.6, 4-CH2), 2.39 (2H, t, J = 7.6, 2-CH2), 2.81–2.87 (8H,
m, 7- 10- 13- and 16-CH2), 3.29 (2H, bt, J = 5.0, 2ꢀ-CH2), 4.37 (2H,bt,
J = 5.0, 1ꢀ-CH2), 5.32–5.45 (10H, m, 5- 6- 8- 9- 11- 12- 14- 15- 17-
+
8- 9- 11- 12- 14- and 15-CH), the NH3 signal was too broad to be
detected. Anal. Calcd for C24H38F3NO4 (461.56): C, 62.45; H, 8.30;
N, 3.03. Found: C, 62.51; H, 8.45; N, 3.02.
+
and 18-CH), the NH3 signal was too broad to be detected. Anal.
Calcd for C24H36F3NO4 (459.54): C, 62.73; H, 7.90; N, 3.05. Found:
C, 62.85; H, 7.75; N, 3.15.
2.4.5. O-palmitoylethanolamine-N-trifluoroacetate salt (2b)
The title compound 2b was obtained from palmitic acid as white
solid; isolated overall yield 55.8 mg (90%). Rf 0.22 (CH2Cl2/MeOH
95:5). Mp 104–105 ◦C. 1H NMR ı: 0.90 (3H, t, J = 7.6, 16-CH3),
1.23–1.33 (24 H, m, 4–15 CH2), 1.58–1.65 (2H, m, 3-CH2), 2.36 (2H,
t, J = 7.0, 2-CH2), 3.26 (2H, bt, J = 5.0, 2ꢀ-CH2), 4.35 (2H, bt, J = 5.0, 1ꢀ-
3.1. Chemical synthesis of NAEs (1a–1g) and OAEs (2a–2g)
are shown in Fig. 1. NAEs (1a–1g) of matched acyl chain lengths
(n = 16–20) have been synthesized in fair yields by the reaction
of the corresponding acid with 2-ethanolamine (3), as shown in
Scheme 2.
+
CH2), the NH3 signal was too broad to be detected. Anal. Calcd for
C20H38F3NO4 (413.52): C, 58.09; H, 9.26; N, 3.39. Found: C, 58.21;
H, 9.12; N, 3.24.
2.4.6. O-stearoylethanolamine-N-trifluoroacetate salt (2c)
The starting compound 3 was linked to palmitic acid (C16),
stearic acid (C18), oleic acid (C18:1), linoleic acid (C18:2),
␣-linolenic acid (C18:3), arachidonic acid (C20:4), or 5,8,11,14,17-
eicosapentaenoic acid (C20:5) by coupling in the presence of COMU
and the base N,N-diisopropylethylamine (DIPEA). After purifica-
tion via flash chromatography, substituted products (1a, 1e, 1f,
1g) were obtained in high yield (85–90%). Column purification
The title compound 2c was obtained from stearic acid as colour-
less white solid; isolated overall yield 60.9 mg (92%). Rf 0.26
(CH2Cl2/MeOH 95:5). Mp 114–115 ◦C. 1H NMR ı: 0.91 (3H, t, J = 7.0,
18-CH3), 1.25–1.36 (28 H, m, 4–17 CH2), 1.61–1.77 (2H, m, 3-CH2),
2.35 (2H, t, J = 7.4, 2-CH2), 3.27 (2H, bt, J = 5.5 2ꢀ-CH2), 4.36 (2H, bt,
J = 5.5, 1ꢀ-CH2), the NH3 signal was too broad to be detected. Anal.
+