2306
R. Schobert, C. Jagusch / Tetrahedron 61 (2005) 2301–2307
(C-10), 189.0 (C-4); m/z (EI, 70 eV) 399 (MC, 30%), 379
(MCKHF, 15%), 216 (45%), 203 (100%), 188 (15%), 161
(10%).
3.8. Melophlins 1 from 8—general procedure
A stirred solution of the appropriate boron difluoride
complex 8 (0.5 mmol) in MeOH (10 mL) was heated
under reflux for 2 h. The cooled reaction mixture was
diluted with ethyl acetate (10 mL) and evaporated under
reduced pressure. The residue was taken up in ethyl acetate
(25 mL), washed with water (10 mL), dried, and evaporated
to yield the respective melophlin 1.
3.7.2. (5S)-3-[10-(Difluoroboryloxy)-40-methyldodecyl-
idene]-1,5-dimethyl-pyrrolidine-2,4-dione 8b. Orange oil
(267 mg, 72%) from (K)-5b (127 mg), Rf 0.27 (CHCl3)
(Found: C, 61.3; H, 8.5; N, 3.9. C19H32BF2NO3 requires C,
61.5; H, 8.7; N, 3.8%). nmax(ATR)/cmK1 2955, 2924, 2854,
1721, 1643, 1569, 1533, 1025; dH (300 MHz; CDCl3) 0.83
(3H, t, JZ6.96 Hz, 120-H), 0.86 (3H, d, JZ6.32 Hz, 40-
CH3), 1.10–1.40 (14H, m, CH2), 1.47 (3H, d, JZ7.14 Hz,
5-CH3) 1.41–1.49 (2H, m, CH2), 1.57–1.68 (1H, m, 40-H),
2.81 (2H, t, JZ7.6 Hz, 20-H), 3.12 (3H, s, NCH3), 3.88 (1H,
q, JZ7.14 Hz, 5-H); dC (75 MHz; CDCl3) 13.9 (C-120),
14.1 (5-CH3), 19.2 (40-CH3), 22.6, 26.8 (CH2), 27.9
(NCH3), 29.2, 29.5, 29.8, 31.7, 31.8 (CH2), 32.5 (C-20),
32.6 (C-40), 36.4 (CH2), 64.9 (C-5), 98.4 (C-3), 170.8 (C-2),
189.7 (C-10), 190.4 (C-4); m/z (EI, 70 eV) 371 (MC, 7%),
351 (MCKHF, 5%), 244 (7%), 230 (40%), 217 (100%), 202
(20%).
3.8.1. Melophlin A 1a. Yellow oil (158 mg, 90%) from 8a
(200 mg), Rf 0.35 (CH2Cl2–MeOH, 19:1). nmax(ATR)/cmK1
2915, 2850, 1717, 1617, 1470, 1250, 948; dH (300 MHz;
CDCl3) 0.84 (3H, t, JZ6.7 Hz, 160-H), 1.18–1.39 (24H, m,
CH2), 1.54–1.66 (2H, m, 30-H), 2.77 (2H, t, JZ7.4 Hz, 20-
H), 2.98 (3H, s, NCH3), 3.68 (2H, s, 5-H), 11.94 (br, 1H,
OH); dC (75 MHz; CDCl3) 14.1 (C-160), 22.6 (C-150), 25.9
(C-30), 28.3 (NCH3), 29.1, 29.2, 29.3, 29.4, 29.5, 29.6, 32.6
(C-20), 57.6 (C-5), 101.6 (C-3), 173.5 (C-2), 187.5 (C-10),
191.2 (C-4); m/z (EI, 70 eV) 351 (MC, 10%), 182 (5%), 168
(30%), 155 (100%), 140 (40%); HR-EI MS; m/z 351.2773
calcd. for C21H37NO3. Found: 351.2770.
3.7.3. 3-[10-(Difluoroboryloxy)-50-methyldodecylidene]-
1,5-dimethyl-pyrrolidine-2,4-dione 8c. Diastereomer a.
Orange oil (156 mg, 42%) from (G)-5b (127 mg), Rf 0.31
(CHCl3) (Found: C, 61.2; H, 8.6; N, 4.1. C19H32BF2NO3
requires C, 61.5; H, 8.7; N, 3.8%). nmax(ATR)/cmK1 2955,
2925, 2856, 1721, 1644, 1570, 1533, 1019, 936; dH
(300 MHz; CDCl3) 0.78–0.86 (6H, m, 50-CH3, 120-H),
1.10–1.40 (15H, m, 50-H, CH2), 1.41 (3H, d, JZ7.14 Hz,
5-CH3) 1.57–1.65 (2H, m, 30-H), 2.78 (2H, t, JZ7.61 Hz,
20-H), 3.12 (3H, s, NCH3), 3.88 (1H, q, JZ7.14 Hz, 5-H);
dC (75 MHz; CDCl3) 13.9 (C-120), 14.0 (5-CH3), 19.3 (50-
CH3), 22.6 (C-110), 23.2 (C-30), 26.8 (C-70), 27.8 (NCH3),
29.20 (C-80), 29.8 (C-100), 31.8 (C-90), 32.4 (C-50), 34.0
(C-2 ), 36.3 (C-40), 36.7 (C-60), 64.9 (C-5), 98.5 (C-3), 170.8
(C-2), 189.2 (C-10), 190.5 (C-4); m/z (EI, 70 eV) 371 (MC,
10%), 351 (MCKHF, 10%), 244 (7%), 233 (30%), 217
(100%), 202 (15%).
3.8.2. Melophlin B 1b. Yellow oil (147 mg, 91%)
from (5S)-8b (185 mg), Rf 0.37 (CH2Cl2–MeOH, 19:1).
nmax(ATR)/cmK1 2924, 2854, 1712, 1613, 1448, 1369, 926;
dH (300 MHz; CDCl3) 0.83 (3H, t, JZ6.9 Hz, 120-H), 0.86
(3H, d, JZ6.3 Hz, 40-CH3), 1.18–1.41 (16H, m, CH2), 1.34
(3H, d, JZ6.95 Hz, 5-CH3), 1.51–1.59 (1H, m, 40-H), 2.70–
2.80 (2H, m, 20-H), 2.93 (3H, s, NCH3), 3.64 (1H, q, JZ
6.95 Hz, 5-H), 12.16 (br, 1H, OH); dC (75 MHz; CDCl3)
14.0 (C-120), 14.7 (5-CH3), 19.2 (40-CH3), 22.6 (C-110),
26.2 (NCH3), 26.9 (C-30), 29.3, 29.6, 29.8, 30.4 31.8 (C-60
to C-100), 32.6 (C-40), 32.9 (C-20), 36.6 (C-50), 62.7 (C-5),
100.3 (C-3), 172.8 (C-2), 188.2 (C-10), 194.6 (C-4);); m/z
(EI, 70 eV) 323 (MC, 10%), 305 (10%), 182 (35%), 169
(100%); HR-EI MS; m/z 323.2460 calcd. for C19H33NO3.
Found: 323.2461.
3.8.3. Melophlin C 1c. Diastereomer a. Yellow oil
(160 mg, 91%) from 8ca (185 mg), Rf 0.29 (CH2Cl2–
MeOH, 19:1). nmax(ATR)/cmK1 2925, 2854, 1712, 1618,
1452, 1371, 926; dH (300 MHz; CDCl3) 0.79 (3H, d, JZ
6.9 Hz, 50-CH3), 0.82 (3H, t, JZ6.9 Hz, 120-CH3), 1.18–
1.41 (15H, m, CH2), 1.34 (3H, d, JZ6.9 Hz, 5-CH3), 1.51–
1.65 (2H, m, 30-H), 2.70–2.76 (2H, m, 20-H), 2.93 (3H, s,
NCH3), 3.64 (1H, q, JZ6.9 Hz, 5-H), 11.60 (br, 1H, OH);
dC (75 MHz; CDCl3) 14.0 (C-120), 14.8 (5-CH3), 19.4 (50-
CH3), 22.6 (C-110), 23.5 (C-30), 26.2 (NCH3), 26.9 (C-70),
29.30 (C-80), 29.90 (C-100), 31.8 (C-90), 32.4 (C-50), 32.7
(C-2 ), 36.4 (C-4 ), 36.8 (C-60), 62.7 (C-5), 100.4 (C-3),
172.7 (C-2), 187.8 (C-10), 194.6 (C-4); m/z (EI, 70 eV) 323
(MC, 10%), 182 (30%), 169 (100%), 154 (60%); HR-EI
MS; m/z 323.2460 calcd. for C19H33NO3. Found: 323.2460.
Diastereomer b Orange oil (17 mg, 5%) Rf 0.26 (CHCl3).
nmax(ATR)/cmK1 2955, 2925, 2856, 1721, 1644, 1570,
1533, 1019; dH (300 MHz; CDCl3) 0.81–0.89 (6H, m, 50-
CH3, 120-H), 1.10–1.40 (15H, m, 50-H, CH2), 1.44 (3H, d,
JZ7.14 Hz, 5-CH3) 1.60–1.71 (2H, m, 30-H), 2.85 (2H, t,
JZ7.61 Hz, 20-H), 3.14 (3H, s, NCH3), 3.88 (1H, q, JZ
7.14 Hz, 5-H).
3.7.4.
3-[10-(Difluoroboryloxy)-myristoylidene]-1-
methyl-pyrrolidine-2,4-dione 8g. Yellow solid (207 mg,
56%) Rf 0.35 (hexane/ethyl acetate, 1:1); mp 114–116 8C
(Found: C, 61.3; H, 8.7; N, 4.0. C19H32BF2NO3 requires C,
61.5; H, 8.7; N, 3.8%). nmax(ATR)/cmK1 2954, 2919, 2850,
1733, 1656, 1569, 1538, 1018; dH (300 MHz; CDCl3) 0.82
(3H, t, JZ6.9 Hz, 140-H), 1.15–1.33 (20H, m, CH2), 1.57–
1.65 (2H, m, 30-H), 2.79 (2H, t, JZ7.6 Hz, 20-H), 3.16 (3H,
s, NCH3), 3.91 (2H, s, 5-H); dC (75 MHz; CDCl3) 14.0
(C-140), 22.5 (C-30), 25.5, 29.0, 29.1 29.2, 29.3, 29.4, 29.5,
29.6, 30.1 (NCH3), 31.8, 33.8 (C-20), 58.9 (C-5), 99.8 (C-3),
171.7 (C-2), 186.9 (C-10), 189.0 (C-4); m/z (EI, 70 eV) 371
(MC, 20%), 351 (MCKHF, 20%), 216 (50%), 203 (100%),
188 (15%), 161 (10%).
Diastereomer b. Yellow oil (12 mg, 91%) from 8cb
(185 mg), Rf 0.24 (CH2Cl2–MeOH, 19:1).
3.8.4. Melophlin G 1g. Yellow oil (80 mg, 92%) from 8g
(100 mg), Rf 0.20 (CH2Cl2–MeOH, 19:1). nmax(ATR)/cmK1
2922, 2852, 1714, 1656, 1602, 1466, 1244; dH (300 MHz;
CDCl3) 0.80 (3H, t, JZ6.8 Hz, CH3), 1.18–1.37 (20H,
m, CH2), 1.51–1.65 (2H, m, CH2), 2.74 (2H, t, JZ7.55 Hz,