P. Wipf et al. / Tetrahedron 56 (2000) 9143±9150
9149
was partitioned between 60 mL of H2O and 150 mL of
CH2Cl2. The layers were separated and the aqueous layer
extracted with CH2Cl2 (2£50 mL). The combined CH2Cl2
extracts were washed with brine (1£40 mL) and dried over
Na2SO4. Chromatography on silica gel (EtOAc/Hexanes,
1:1, followed by EtOAc) afforded westiellamide (10,
214 mg, 20%) and cyclotetramer 11 (266 mg, 25%) as
amorphous solids.
308 (30), 138 (75), 72 (80); HRMS calcd for C27H42N6O6:
546.3166, found: 546.3175.
5. [a]D2131 (c0.66, CH2Cl2, 238C); IR (neat) 3393,
2966, 2933, 2875, 1683, 1653, 1521, 1457, 1378, 1204,
;
1037, 736 cm21
1H NMR d 6.78 (d, 1H, J9.6 Hz),
4.77±4.67 (m, 2H), 4.18 (d, 1H, J6.6 Hz), 2.35±2.26
(m, 1H), 1.45 (d, 3H, J6.3 Hz), 1.04 (d, 3H, J6.9 Hz),
0.98 (d, 3H, J6.8 Hz); 13C NMR d 170.9, 168.2, 80.3,
74.7, 51.9, 31.4, 21.9, 19.4, 17.4; MS (EI) m/z (relative
intensity) 728 (M1, 100), 713 (20), 685 (20), 670 (30),
644 (20), 545 (25), 504 (15), 462 (35), 422 (15), 322 (20),
280 (30), 138 (90); HRMS calcd for C36H56N8O8: 728.4221,
found: 728.4178.
10. Mp 1688 C (dec.); [a]2D3130.0 (c0.1, MeOH); IR
(neat) 3376, 2965, 1694, 1651, 1526, 1456, 1372, 1202,
1
1038 cm21; H NMR d 7.76 (d, 1H, J7.9 Hz), 4.80 (dq,
1H, J8.7, 6.3 Hz), 4.65 (ddd, 1H, J7.9, 3.1, 2.1), 4.22
(dd, 1H, J8.7 Hz, 2.1 Hz), 2.32±2.26 (m, 1H), 1.58 (d, 3H,
J6.3 Hz), 0.89 (d, 3H, J7.0 Hz), 0.81 (d, 3H, J7.0 Hz);
13C NMR d 170.6, 168.5, 82.7, 73.8, 52.4, 31.5, 22.0, 18.7,
16.9; MS (EI) m/z (relative intensity) 546 (M1, 7), 531 (2),
503 (3), 462 (4), 447 (2), 363 (2), 308 (3), 280 (4), 252 (2),
183 (3), 168 (2), 153 (2), 138 (15), 69 (15); HRMS calcd for
C27H42N6O6: 546.3166, found: 546.3158.
Acknowledgements
This work was supported by a grant from the National
Institutes of Health (GM 55433). We thank Dr Steve Geib
(University of Pittsburgh) for X-ray analyses of 3 and 11.
11. Mp 2428 C (dec.); [a]D2169.0 (c0.1, MeOH); IR 3389,
2965, 2932, 1715, 1684, 1653, 1576, 1516, 1456, 1379,
1
1277, 1202, 1146, 1038, 864 cm21; H NMR d 7.31 (d,
References
1H, J9.7 Hz), 4.81 (dq, 1H, J7.6, 6.3 Hz), 4.69 (dd,
1H, J9.7, 5.0 Hz), 4.22 (d, 1H, J7.6 Hz), 2.17±2.04
(m, 1H), 1.50 (d, 3H, J6.3 Hz), 0.92±0.88 (m, 6H); 13C
NMR d 171.2, 169.4, 81.1, 74.4, 51.7, 31.7, 21.9, 18.9, 17.6;
MS (EI) m/z (relative intensity) 728 (M1, 100), 713 (20),
685 (40), 670 (30), 657 (30), 644 (40), 628 (20), 545 (24),
462 (20), 363 (14), 322 (12), 280 (30), 252 (20), 223 (20),
138 (90), 124 (30), 98 (40), 84 (55), 72 (100); HRMS calcd
for C36H56N8O8: 728.4221, found: 728.4286.
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1
1468, 1453, 1375, 1225, 1192, 1142, 1074, 1017 cm21; H
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NMR d 6.79 (d, 1H, J10.3 Hz), 5.15 (dq, 1H, J6.5,
2.7 Hz), 4.15 (dd, 1H, J10.3, 9.8 Hz), 4.15 (d, 1H,
J2.7 Hz), 2.12±2.00 (m, 1H), 1.28 (d, 3H, J6.6 Hz),
1.05 (d, 3H, J6.7 Hz), 0.99 (d, 3H, J6.7 Hz); 13C NMR
d 173.2, 172.5, 79.3, 72.8, 54.5, 31.7, 20.1, 19.1, 19.0; MS
(EI) m/z (relative intensity) 364 (M1, 8), 321 (12), 308 (60),
280 (80), 252 (25), 234 (20), 183 (20), 170 (25), 138 (25),
124 (30), 84 (20), 72 (45); HRMS m/z calcd for C18H28N4O4:
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;
10005, 845 cm21
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4.88 (dq, 1H, J9.0, 6.1 Hz), 4.52 (dd, 1H, J7.7,
4.8 Hz), 4.19 (d, 1H, J9.0 Hz), 2.35±2.26 (m, 1H), 1.51
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J6.9 Hz); 13C NMR d 169.4, 167.2, 79.1, 74.8, 52.5,
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