522 J. Agric. Food Chem., Vol. 56, No. 2, 2008
Naef et al.
3H); 1.23 (d, 2H); 1.35–1.55 (m, 4H); 2.17–2.40 (m, 4H); 3.89 (sext.,
1H). 13C NMR: 83.2 (s); 76.1 (s); 66.5 (d); 31.1 (t); 29.4 (t); 22.1 (q);
22.0 (t); 18.4 (t); 13.6 (q).
(()-(4E)-4-Nonen-2-ol (55). In a flask, flame-dried under argon, 53
(5.32 g, 38 mmol) in toluene/THF 1:1 (50 mL) was added to LiAlH4
(4.64 g) in toluene/THF 1:1 (50 mL), the mixture was stirred at 90 °C
for 22 h. After cooling with an ice bath, NH4Cl was slowly added,
followed by HCl (10%). NaCl was added, and the mixture was extracted
with ether (2×) and dried over MgSO4, and the solvent was removed.
A 500 mg portion was bulb-to-bulb distilled to give 55, which was
used in the next step. b.p.: 140°/12 Torr. MS: m/z 142 (M+·, 3), 124
(4), 109 (3), 98 (53), 83 (10), 69 (46), 56 (83), 45 (100), 41 (38), 27
(15). 1H NMR: 0.90 (t, 3H); 1.18 (d, 3H); 1.25–1.40 (m, 4H); 2.00–2.25
(m, 4H); 3.78 (sext., 1H); 5.40 (ddd, J ) 15.2, 7.0, 6.8, 1H); 1.52
(ddd, J ) 15.2, 7.0, 7.0, 1H). 13C NMR: 134.7 (d); 125.8 (d); 67.2 (d);
42.6 (t); 32.4 (t); 31.6 (t); 22.6 (q); 22.2 (t); 13.9 (q).
(()-(3E)-1-Methyl-3-octenyl 4-methylbenzenesulfonate (57) was
prepared from 55 following Method A, yield: 53%. 1H NMR
(characteristic signals): 2.45 (s, 3H); 4.58 (sext., 1H); 5.64 (ddd, J )
15.1, 7.0, 7.0, 1H); 5.41 (ddd, J ) 15.1, 7.0, 7.0, 1H). 13C NMR: 144.4
(s); 135.0 (d); 134.6 (s); 129.7 (2s); 127.7 (2s); 123.4 (d); 80.1 (d);
39.7 (t); 32.2 (t); 31.4 (t); 22.2 (t); 21.6 (q); 20.3 (q); 13.9 (q).
(()-S-[(3E)-1-Methyl-3-octenyl] ethanethioate (59) was prepared
following Method B, using 57 as starting material. Yield: 63%, purity:
95% (GC/MS). MS: m/z 200 (M+·, 0.5), 157 (7), 124 (93), 103 (21),
95 (20), 81 (35), 68 (48), 61 (16), 55 (27), 43 (100), 27 (9). 1H NMR:
0.88 (t, 3H); 1.27 (d, 3H); 1.25–1.40 (m, 4H); 2.00 (m, 2H); 2.22 (m,
2H); 2.29 (s, 3H); 3.58 (sext., 1H); 5.35 (ddd, J ) 15.3, 6.8, 6.8, 1H);
5.48 (ddd, J ) 15.3, 6.6, 6.6, 1H). 13C NMR: 195.9 (s); 133.9 (d);
126.1 (d); 39.6 (t); 39.5 (d); 32.2 (t); 31.6 (t); 30.8 (q); 22.2 (t); 20.5
(q); 13.9 (q).
Figure 8. Syntheses of compounds 15, 24, 16, and 25.
(()-2-Mercapto-4-heptanol (17) was prepared following Method C
from 51. Two diastereoisomers (1:1), yield: 40%, purity: 99%. MS
(both isomers identical): m/z 148 (M+·, 4), 130 (17), 114 (42), 99 (32),
87 (23), 81 (21), 73 (45), 71 (64), 61 (94), 55 (100), 43 (58), 31 (8).
1H NMR (both isomers): 0.94 (t, 3H); 1.35–1.60 (m, 4H); 1.39 and
1.40 (d, 3H); 1.62 and 1.70 (d, 1H); 2.05 (br. s, 1H); 3.09 and 3.20 (m,
1H); 3.72 and 3.88 (m, 1H). 13C NMR (one isomer established by
HMBC): 70.2 (d); 48.4 (t); 40.1 (t); 32.9 (d); 25.8 (q); 18.6 (t);
14.1 (q).
(()-(4E)-4-Heptene-2-thiol (15) and (()-(4E)-4-nonene-2-thiol (24).
See Figure 8. (()-4-Heptyn-2-ol (52) was prepared following the
procedures described by Jones and Knight (21). Yield: 46%, purity:
95%. MS: m/z 112 (M+·, 0), 97 (12), 68 (86), 67 (100), 53 (38), 45
(59), 41 (24), 27 (8). 1H NMR: 1.12 (t, 3H); 1.24 (d, 3H); 2.1–2.4 (m,
4H); 3.90 (sext., 1H). 13C NMR: 84.6 (s); 75.5 (s); 66.6 (d); 29.4 (t);
22.2 (q); 14.2 (q); 12.4 (t).
(()-(4E)-4-Hepten-2-ol (54). Same procedure as described for 55,
but using 52 as starting material. The product was purified using a
Vigreux-column. b.p.: 60°/15 Torr. Yield: 33%, purity: 90%. MS: m/z
114 (M+·, 1), 96 (6), 81 (10), 70 (90), 55 (84), 45 (100), 42 (32), 27
(11). 1H NMR: 0.98 (t, 3H); 1.20 (d, 3H); 2.0–2.3 (m, 4H); 3.78 (sext.,
1H); 5.40 (ddd, J ) 15.7, 7.6, 7.6, 1H); 5.59 (ddd, J ) 15.7, 6.2, 6.2,
1H). 13C NMR: 136.2 (d); 124.8 (d); 67.2 (d); 42.5 (t); 25.7 (t); 22.6
(q); 13.8 (q).
(()-(3E)-1-Methyl-3-hexenyl 4-methylbenzenesulfonate (56), Method
A, yield 73%. 1H NMR: 0.90 (t, 3H); 1.25 (d, 3H); 1.92 (m, 2H);
2.15–2.35 (m, 2H); 2.44 (s, 3H); 4.57 (sext., 1H); 5.16 (ddd, J ) 15.7,
7.1, 7.1, 1H); 5.45 (ddd, J ) 15.7, 5.8, 5.8, 1H); 7.32 (d, 2H); 7.79 (d,
2H). 13C NMR: 144.4 (s); 136.4 (d); 134.6 (s); 129.7 (2s); 127.8 (2s);
80.1 (d); 39.6 (t); 25.5 (t); 21.6 (q); 20.4 (t); 20.4 (q); 13.5 (q).
(()-S-[(3E)-1-Methyl-3-hexenyl] ethanethioate (58) was prepared
following Method B, yield: 39%, purity: 95% (GC/MS). MS: m/z 172
(M+·, 0), 129 (2), 103 (12), 96 (57), 81 (38), 61 (16), 55 (22), 43
(100), 27 (8). 1H NMR: 0.97 (t, 3H); 1.27 (d, 3H); 2.02 (m, 2H); 2.25
(m, 2H); 2.30 (s, 3H); 3.57 (sext., 1H); 5.36 (ddd, J ) 15.7, 6.2, 6.2,
1H); 5.52 (ddd, J ) 15.7, 7.6, 7.6, 1H). 13C NMR: 195.9 (s); 135.4
(d); 125.1 (d); 39.5 (d); 39.5 (t); 30.8 (q); 25.6 (t); 20.4 (q); 13.8 (q).
(()-(4E)-4-Heptene-2-thiol (15) was prepared following Method C,
yield: 71%, purity: 95%. MS: m/z 130 (M+·, 1), 115 (2), 101 (24), 96
(9), 81 (11), 69 (12), 61 (100), 55 (37), 45 (5), 41 (43), 27 (16). 1H
NMR: 0.98 (t, 3H); 1.30 (d, 3H); 1.62 (d, 1H); 2.03 (m, 2H); 2.21 (m,
2H); 2.96 (m, 1H); 5.39 (ddd, J ) 15.2, 6.2, 6.2, 1H); 5.55 (ddd, J )
15.2, 6.6, 6.6, 1H). 13C NMR: 135.4 (d); 125.8 (d); 44.0 (t); 35.5 (d);
25.6 (t); 24.5 (q); 13.8 (q).
(()-(4E)-4-Nonene-2-thiol (24) was prepared following Method C,
using 59 as starting material. Yield: 33%, purity: 93%. MS: m/z 158
(M+·, 4), 143 (2), 124 (7), 115 (6), 101 (43), 81 (12), 69 (20), 61
1
(100), 55 (46), 41 (28), 27 (10). H NMR: 0.90 (t, 3H); 1.30 (d, 3H);
1.25–1.40 (m, 4H); 1.62 (d, 1H); 2.02 (m, 2H); 2.22 (m, 2H); 2.97
(sext., 1H); 5.38 (ddd, J ) 15.4, 7.0, 7.0, 1H); 5.51 (ddd, J ) 15.4,
7.0, 7.0, 1H). 13C NMR: 133.9 (d); 126.7 (d); 44.0 (t); 35.5 (d); 32.3
(t); 31.6 (t); 24.5 (q); 22.2 (t); 13.9 (q).
(()-(4Z)-4-Heptene-2-thiol (16) and (()-(4Z)-4-nonene-2-thiol (25).
See Figure 8.
(()-(4Z)-4-Hepten-2-ol (60). A solution of 52 (4.03 g, 36 mmol) in
hexane (400 mL) was hydrogenated at room temperature in the presence
of Pd 5% on BaSO4 (40 mg). After filtration and concentration, the
pure 60 (3.41 g, yield: 83%) was used in the next step.
(()-(3Z)-1-Methyl-3-hexenyl 4-methylbenzenesulfonate (62) was
prepared following Method A, using 60 as starting material. Yield:
1
7%. H NMR: 0.90 (t, 3H); 1.26 (d, 3H); 1.93 (m, 2H); 2.2–2.4 (m,
2H); 2.43 (s, 3H); 4.58 (sext., 1H); 5.16 (ddd, J ) 12.5, 1H); 5.43
(ddd, J ) 12.5, 1H); 7.32 (d, 2H); 7.79 (d, 2H). 13C NMR: 144.4 (s);
135.3 (d); 134.5 (s); 129.7 (2s); 127.8 (2s); 79.9(d); 34.1 (t); 21.6 (q);
20.6 (t); 20.3(q); 14.0 (q).
(()-S-[(3Z)-1-Methyl-3-hexenyl] ethanethioate (64) was prepared
following Method B, using 62 as starting material. Purification was by
chromatography on silica gel using 5% ether in pentane. Yield: 74%,
purity by GC/MS: ca. 80%. MS: m/z 172 (M+·, 1), 129 (7), 103 (18),
1
96 (92), 81 (50), 61 (20), 55 (22), 43 (100), 27 (6). H NMR: 0.97 (t,
3H); 1.28 (d, 3H); 2.05 (m, 2H); 2.30 (s, 3H); 2.31 (m, 2H); 3.58 (sext.,
1H); 5.3–5.6 (m, 2H). 13C NMR: 196.0 (s); 134.4 (d); 125.0 (d); 39.5
(d); 33.8 (t); 30.8 (q); 20.7 (t); 20.5 (q); 14.1 (q). The compound
decomposed before NMR measurements could be taken.
(()-(4Z)-4-Heptene-2-thiol (16) was prepared following Method C,
using 64 as starting material. Purification was by chromatography on
silica gel with pentane. Yield: 90%, purity by GC/MS: 85%. MS: m/z
130 (M+·, 2), 115 (3), 101 (37), 96 (13), 81 (20), 61 (100), 55 (38), 45
(7), 41 (38), 27 (17).
(()-4-Nonyn-2-ol (53) was prepared following the procedures
described by Jones and Knight (21). Pure compound 53 was obtained
(6.51 g) by chromatography on silica gel using 30% ether in pentane.,
yield: 35%, purity: 99%. MS: m/z 140 (M+·, 0), 125 (3), 96 (11), 81
(52), 67 (33), 54 (100), 45 (50), 43 (23), 27 (12). 1H NMR: 0.91 (t,
(()-(4Z)-4-Nonen-2-ol (61). A solution of 53 (11.9 g, 85 mmol) in
ethanol (100 mL) was hydrogenated at room temperature in the presence
of 5% Pd on CaCO3 (Strem Chemicals, 500 mg). After filtration and
concentration, the product was purified by chromatography on silica
gel using pentane with 20% ether. A 7.87 g portion of compound 61