J Am Oil Chem Soc
The progress of the reaction was monitored by TLC. The
enzyme was filtered off and washed with dichloromethane.
Evaporation of the solvent provided a crude solid product,
which was purified by crystallization in acetone. Pure
amide 2-R (0.44 g) was a white solid of >98% purity (GC);
1H NMR (δ ppm): 5.54 (m, 3H; NH2; CH ), 5.39 (m,
1H; CH ), 3.60 (qn J = 6.3 Hz, 1H; CHOH), 2.21 (m,
4H; CHCH2CH ; CH2CO ), 2.04 (m, 2H), 1.62
(qn J = 7.3 Hz, 2H), 1.45 (m, 3H), 1.30 (m, 15H), 0.87
(t J = 6.5 Hz; CH3); 13C NMR: 176.08 (s; CO ),
855.2; and GC–MS (EI, 70 eV) m/z (%): 529 (0) [M+],
282 (2), 188 (14), 187 (97), 103 (31), 97 (27), 75 (20),
73 (100), 55 (32), 41 (13).
(S,Z)-N,12-Dihydroxyoctadec-9-Enamide (3-S)
Hydroxamic acid 3-S was synthesized in the same way as
compound 3-R, and its purity was >98% (GC after derivati-
zation of the sample). Its IR, MS, and NMR spectra mat-
ched those determined for enantiomer 3-R.
133.10 (d;
CH ), 125.24 (d;
CH ), 71.39 (d;
CHOH ), 36.74 (t), 35.82 (t), 35.26 (t), 31.75 (t), 29.43
(t), 29.27 (t), 29.02 (t, 2xCH2), 28.94 (t), 27.23 (t), 25.63
(t), 25.38 (t), 22.53 (t), 14.01 (q; CH3); IR (cm−1, neat):
3353.6, 3184.0, 2922.4, 2850.8, 1658.4, 1631.8, 1469.4,
1072.9, 813.1; and GC MS (EI, 70 eV) m/z (%):
297 (0) [M+], 279 (1) [M+–18], 183 (5), 97 (10), 72 (54),
69 (15), 59 (100), 55 (70), 44 (22), 43 (35), 41 (36).
(R,Z)-12-Hydroxy-N-Methyloctadec-9-Enamide (4-R)
A solution of potassium hydroxide (1.1 g, 0.019 mol) in
methanol (5 mL) was added to a solution of methylamine
hyꢁdrochloride (0.9 g, 0.013 mol) in methanol (10 mL) at
0 C. The mixture was stirred in an ice bath for 15 min,
and then, the precipitated potassium chloride was filtered
off. The filtrate was added to methyl esters of RA (1-R;
2 g, 0.006 mol) and, after thorough mixing, was maintained
at room temperature for 24 hours. Then, Dowex 50WX8
resin was added to obtain a pH of 6, and the solution was
filtered. The solvent was evaporated, and the crude product
was purified on a silica gel column using ethyl acet-
ate/hexane (40:60, v/v) as an eluent, providing compound
(S,Z)-12-Hydroxyoctadec-9-Enamide (2-S)
It was prepared analogously as compound 2-R. Amide 2-S
was a solid of >98% purity (GC). Its IR, MS, and NMR
spectra matched those determined for compound 2-R.
1
(R,Z)-N,12-Dihydroxyoctadec-9-Enamide (3-R)
4-R of >99% purity (GC); H NMR (δ ppm): 5.54 (m, 2H;
CH ; NH ), 5.38 (m, 1H; CH ), 3.60 (qn J = 5.9 Hz,
1H; CHOH), 2.79 (d J = 4.8 Hz, 3H; NHCH3), 2.18
(m, 4H), 2.04 (m, 2H), 1.35 (br.m, 18H), 0.87 (t J = 6.5 Hz,
3H; CH3); 13C NMR: 173.92 (s; CO ), 132.78 (d;
CH ), 125.24 (d; CH ), 71.26 (d; CHOH ), 36.66
(t), 36.36 (t), 35.19 (t), 31.67 (t), 29.36 (t), 29.19 (t), 29.06
(t), 29.01 (t), 28.89 (t), 27.15 (t), 26.01 (q; NHCH3),
A solution of potassium hydroxide (1.1 g, 0.019 mol) in
methanol (5 mL) and a solution of hydroxylamine hydro-
chloride (0.9 g, 0.013 mol) in methanol (10 mL) were
obtained by heating to the boiling point of the solvent.
ꢁ
Then, both were cooled to 30 C, and a solution of KOH
was added to the NH2OHꢀHCl solution. The mixture was
stirred in an ice bath for 15 min, and then, the precipitated
potassium chloride was filtered off. The filtrate was added
to methyl ester of RA (1-R; 2 g, 0.006 mol) and, after thor-
ough mixing, was maintained at room temperature for
24 hours. Then, Dowex 50WX8 resin was added to obtain
a pH of 6, and the solution was filtered. Evaporation of
methanol delivered a crude product, which was subjected
to crystallization in acetone giving pure (>96%, GC after
25.58 (t), 25.55 (t), 22.44 (t), 13.90 (q; CH3); IR (cm−1
,
neat): 3297.6, 2925.2, 2854.4, 1648.1, 1560.9, 1046.9,
725.7; and GC–MS (EI, 70 eV) m/z (%): 311 (0) [M+],
293 (1) [M+–18], 97 (8), 86 (53), 73 (100), 69 (12),
58 (36), 55 (56), 43 (21), 41 (23).
(S,Z)-12-Hydroxy-N-Methyloctadec-9-Enamide (4-S)
1
derivatization of the sample) hydroxamic acid; H NMR
The method for the preparation of compound 4-S was anal-
ogous to the one used for its enantiomer 4-R (purity >99%,
GC). Its IR, MS, and NMR spectra were the same as those
of derivative 4-R.
(500 MHz, δ ppm): 9.39 (br.s, 1H; -NH ), 5.52 (m, 1H;
CH ), 5.38 (m, 1H; CH ), 3.62 (qn J = 6 Hz, 1H;
CHOH), 2.20 (m, 2H; CHCH2CH ), 2.11 (t J = 7.3 Hz,
2H; CH2CO ), 2.03 (m, 2H; CHCH2CH2 ), 1.59 (m,
2H), 1.46 (m, 3H), 1.29 (m, 16H), 0.87 (t J = 6.8 Hz, 3H;
CH3); 13C NMR (500 MHz): 171.69 (s; CO ), 133.24
(d; CH ), 125.22 (d; CH ), 71.61 (d; CHOH ),
36.68 (t), 35.23 (t), 32.84 (t), 31.81 (t), 29.36 (t), 29.33 (t),
28.86 (t), 28.84 (t), 28.82 (t), 27.18 (t), 25.69 (t), 25.28 (t),
22.60 (t), 14.07 (q; CH3); IR (cm−1, neat): 3403.3,
3278.5, 3015.5, 2918.6, 2847.6, 1662.6, 1621.2, 1077.4,
Preparation of (R)- and (S)-3-Hydoxynonanoic Acid
Derivatives
The first step was preparation of dimethyl acetals of
3-hydroxynonanal, which were then oxidized to corresponding
methyl esters (5-R and 5-S) in the way described by Takeda
et al. (Takeda et al., 1997).
J Am Oil Chem Soc (2019)