920
L.-K. Sy, G. D. Brown / Tetrahedron 58 #2002) 909±923
+100); EIMS m/z +rel. int.) 281 +70), 249 +91), 231 +60), 204
+100), 195 +100); 21:20 +1 mg, 3%, Rt 12.4 min, 30% EtOAc/
n-hexane); 26a: H NMR d +CDCl3) ppm: 9.90 +1H, d,
of the mixture. 1H NMR d +CDCl3) ppm: 5.25 +1H, s), 3.94
+1H, dd, J11.6, 6.7 Hz), 3.29 +1H, dd, J11.6, 4.5 Hz),
1.53 +3H, s), 0.92 +3H, d, J7.3 Hz), 0.89 +3H, d, J
6.1 Hz)Ðsee Table 2; 13C NMRÐsee Table 1; 32b: Oil.
+2.5 mg, 8%; Rt 11.8 min, 50% EtOAc/n-hexane). [a]D
2175 +c 0.3, CHCl3); IR nmax +CHCl3): 3015, 2932, 2876,
1
J2.6Hz), 3.64 +3H, s), 3.19 +1H, m), 1.28 +3H, s), 1.22
+3H, d, J7.2 Hz), 0.89 +3H, d, J6.5 Hz); 27a, 28a and
29a13Ðisolated as a mixture with 13a and identi®ed by
characteristic NMR resonances in the mixture +ca. 2%
each from 1H NMR of crude mixture): dH 5.51 +H-5)
ppm; dH 5.82 +H-5), 4.72 +H-15a/b), 4.69 +H-15a/b) ppm;
dH 5.37 +H-5), 5.26+H-3) ppm, respectively; 30a: Oil.
+1.5 mg, 4%; Rt 13.0 min, 30% EtOAc/n-hexane). The
sample was unstable under laboratory conditions after
puri®cation and decomposed into compounds 13a, 21, 26a
1
1713, 1456cm 21; H NMR d +CDCl3) ppm: 8.07 +1H, s),
4.20 +1H, dd, J10.9, 4.7 Hz), 4.07 +1H, dd, J10.9,
6.3 Hz), 2.55 +1H, ddd, J17.1, 8.7, 5.9 Hz), 2.36+2H,
m), 2.24 +1H, m), 2.13 +3H, s), 1.08 +3H, d, J7.0 Hz),
1.00 +3H, d, J6.7 Hz)Ðsee Table 4; 13C NMRÐsee
Table 3; HREIMS m/z +rel. int.) 268.1671 [M1, C15H24O4
requires 268.1675] +10), 250 +36), 222 +21), 207 +50), 182
+53), 165 +100), 124 +100).
1
and 31a. H NMR d +CDCl3) ppm: 9.56+1H, s), 5.25 +1H,
s), 3.68 +3H, s), 3.54 +3H, s), 3.20 +1H, dq, J1.8, 7.1 Hz),
2.73 +1H, dq, J7.1, 6.8 Hz), 2.46 +1H, m), 2.39 +1H, m),
2.09 +3H, s), 1.36+3H, s), 1.21 +3H, d, J6.8 Hz), 1.16 +3H,
d, J7.1 Hz), 0.93 +3H, d, J6.4 Hz), 0.88 +3H, d, J
6.3 Hz)Ðsee Table 4; 13C NMRÐsee Table 3; CIMS:
281 +3), 269 +10), 251 +60), 249 +100), 237 +25), 209 +35);
31a:21 +1 mg, 3%; Rt 20.8 min, 30% EtOAc/n-hexane).
Compound 13c:22 Oil. +11 mg, 35%; Rt 10.2 min, n-hexane).
[a]D140.8 +c 0.13, CHCl3). IR nmax +CHCl3): 3020, 2958,
1
2937, 2853 cm21; H NMR d +CDCl3) ppm: 6.22 +1H, s,
H-5), 3.03 +1H, sept, J6.9 Hz, H-11), 1.77 +3H, s, H-15),
0.99 +3H, d, J5.9 Hz, H-14), 0.96+3H, d, J6.9 Hz, H-12/
13), 0.95 +3H, d, J6.9 Hz, H-12/13); 13C NMRÐ135.3 +C,
C-4), 135.0 +C, C-7), 127.9 +C, C-6), 120.4 +CH, C-5), 43.2
Compound 6b: Oil. +12 mg, 40%; Rt 7.6min, 50% EtOAc/
n-hexane). [a]D142.4 +c 0.18, CHCl3); IR nmax +CHCl3):
2930, 2872, 1456cm 21; 1H NMR d +CDCl3) ppm: 5.59 +1H,
s), 3.90 +1H, dd, J8.4, 8.4 Hz), 3.37 +1H, dd, J9.6,
8.4 Hz), 2.83 +1H, m), 2.06+1H, dd, J18.4, 6.8 Hz), 1.66
+3H, s), 0.96+3H, d, J6.9 Hz), 0.90 +3H, d, J6.6 Hz)Ð
see Table 2; 13C NMRÐsee Table 1; HREIMS m/z +rel. int.)
220.1822 [M1, C15H24O requires 220.1827] +70), 205 +55),
177 +42), 165 +100); 12b: Oil. +4.5 mg, 15%; Rt 8.4 min,
+CH, C-1), 34.6+CH, C-10), 31.8 +CH , C-9), 31.2 +CH2,
2
C-3), 28.2 +CH2, C-2), 28.1 +CH, C-11), 24.1 +CH3, C-15),
23.9 +CH2, C-8), 21.0 +CH3, C-12/13), 20.5 +CH3, C-14),
20.4 +CH3, C-12/13); 16c: Oil. +4.5 mg, 15%; Rt 12.0 min,
n-hexane). The sample was unstable under laboratory con-
ditions following puri®cation and was converted into 22c
1
and 26c within 24 h. Tentative identi®cation by H NMR
only +however, cf. data for compound 16 in the preceding
paper).3 1H NMR d +CDCl3) ppm: 6.10 +1H, s, H-5), 4.93
+1H, dd, J6.4, 6.4 Hz, H-3), 2.53 +1H, m, H-2), 2.07 +1H,
m, H-7), 1.77 +3H, s, H-15), 0.94 +3H, d, J6.6 Hz, H-12/
13), 0.88 +3H, d, J6.6 Hz, H-12/13), 0.85 +3H, d, J
6.4 Hz, H-14); 20c: Oil. +2.5 mg, 8%; Rt 31.3 min, 10%
EtOAc/n-hexane). [a]D211.0 +c 0.3, CHCl3); IR nmax
1
50% EtOAc/n-hexane). H NMR d +CDCl3) ppm: 5.65
+1H, s), 4.18 +1H, dd, J9.1, 9.0 Hz), 3.52 +1H, dd, J
9.1, 5.6Hz), 2.46+1H, m), 1.68 +3H, s), 1.10 +3H, d, J
7.4 Hz), 0.93 +3H, d, J6.5 Hz)Ðsee Table 2; 13C NMRÐ
see Table 1; HREIMS m/z +rel. int.) 220.1820 [M1, C15H24O
requires 220.1827] +40), 205 +42), 165 +100); 13b: Oil.
+2.5 mg, 9%; Rt 9.9 min, 50% EtOAc/n-hexane). [a]D
1100.3 +c 0.38, CHCl3); IR nmax +CHCl3): 3538 +br),
1
+CHCl3): 2959, 2928, 1734, 1717, 1458 cm21; H NMR d
+CDCl3) ppm: 9.81 +1H, dd, J1.6, 1.6 Hz), 6.05 +1H, s),
2.12 +3H, s), 2.07 +3H, s), 0.95 +6H, d, J6.7 Hz), 0.94 +3H,
d, J6.7 Hz), 0.93 +3H, d, J7.1 Hz), 0.90 +3H, d, J
6.5 Hz), 0.65 +3H, d, J6.8 Hz)Ðsee Table 2; 13C
NMRÐsee Table 1; CIMS: 474 [M1] +7), 431 +2), 281
+6), 237 +100), 219 +14); HREIMS m/z +rel. int.) 474.3704
[M1, C30H50O4 requires 474.3709] +3), 432 +3), 416+3), 237
+100), 219 +36), 195 +100); 26c: Oil. +1 mg, 3%; Rt 50.8 min,
13% EtOAc/n-hexane and 47.3 min in 10% EtOAc/n-hex-
ane). [a]D178.4 +c 0.3, CHCl3); IR nmax +CHCl3): 3580,
1
3009, 2965, 2928, 2874, 2830, 1456 cm21; H NMR d
+CDCl3) ppm: 6.22 +1H, s), 3.48 +2H, m), 3.14 +1H, sext,
J7.1 Hz), 1.76+3H, s), 1.01 +3H, d, J5.9 Hz), 0.97 +3H,
d, J7.1 Hz)Ðsee Table 2; 13C NMRÐsee Table 1;
HREIMS m/z +rel. int.) 220.1821 [M1, C15H24O requires
220.1827] +27), 189 +100), 159 +33), 133 +26), 119 +40);
14b: Oil. +1.5 mg, 6%; Rt 13.7 min, 50% EtOAc/n-hexane).
1H NMR d +CDCl3) ppm: 4.29 +1H, dd, J9.2, 8.9 Hz), 3.60
+1H, dd, J9.2, 6.0 Hz), 2.92 +1H, s), 2.51 +1H, m), 1.35
+3H, s), 1.11 +3H, d, J7.0 Hz), 0.91 +3H, d, J6.6 Hz)Ð
see Table 2; 13C NMRÐsee Table 1; HREIMS m/z +rel. int.)
236.1774 [M1, C15H24O2 requires 236.1776] +10), 221 +12),
178 +50), 165 +100); 18b: Oil. +1 mg, 3%; Rt 21.3 min, 50%
EtOAc/n-hexane). [a]D171.4 +c 0.98, CHCl3); IR nmax
+CHCl3): 3603, 3400 +br), 3011, 2963, 2924, 2858, 1711,
1460 cm21; 1H NMR d +CDCl3) ppm: 5.17 +1H, dd, J1.8,
1.8 Hz), 4.16+1H, dd, J11.1, 2.8 Hz), 3.33 +1H, dd, J
11.1, 1.1 Hz), 2.40 +1H, m), 2.36+1H, m), 2.25 +1H, br s,
±OH), 2.15 +3H, s), 0.99 +3H, d, J7.1 Hz), 0.87 +3H, d,
J6.4 Hz)Ðsee Table 2; 13C NMRÐsee Table 1;
HREIMS m/z +rel. int.) 254.1884 [M1, C15H26O3 requires
254.1882] +2), 236+56), 181 +45), 178 +70), 150 +100); 21b:
1
3393 +br), 3028, 2963, 2936, 2872, 1732, 1456 cm21; H
NMR d +CDCl3) ppm: 9.91 +1H, d, J2.6Hz), 2.58 +1H,
d sept, J6.9, 6.7 Hz), 1.28 +3H, s), 0.93 +3H, d, J6.7 Hz),
0.89 +3H, d, J6.7 Hz), 0.75 +3H, d, J6.7 Hz)Ðsee Table
4; 13C NMRÐsee Table 3; CIMS: 253 [M112H2O] +10),
237 +41), 235 +60), 225 +100); HREIMS m/z +rel. int.)
238.1928 [M12O2, C15H26O2 requires 238.1933] +5), 224
+16), 209 +30), 195 +100); 27c, 28c and 29cÐisolated as a
mixture with 13c and identi®ed by characteristic resonances
1
1
in H NMR +ca. 2% each from H NMR of the crude
mixture):22 dH 5.61 +H-5) ppm; dH 5.90 +H-5), 4.72
+H-15a/b), 4.66 +H-15a/b) ppm; dH 5.48 +H-5), 5.30 +H-3)
ppm, respectively; 30c: Oil. +1.5 mg, 5%; Rt 11.7 min, 10%
EtOAc/n-hexane). Sample was unstable under laboratory
conditions after isolation and decomposed into 13c, 22c
1
+ca. 5% by H NMR of the crude mixture; isolated as a
mixture with 12b). NMR assignments made by 2D-NMR
1
and 26c within 24 h. Tentative identi®cation by H NMR