Communications
d = 215.3, 171.2, 156.3, 146.9, 132.0, 130.7, 128.6, 122.9, 114.5, 110.3,
106.0, 97.4, 96.9, 79.1, 78.8, 78.5, 78.0, 77.6, 74.0, 72.4, 71.3, 71.1, 64.2,
63.2, 49.1, 45.8, 40.8, 40.0, 39.5, 37.0, 35.1, 34.9, 34.8, 33.6, 32.6, 31.7,
31.7, 30.1, 29.9, 29.0, 28.4, 26.2, 26.1, 24.9, 23.2, 21.1, 19.7, 18.9, 18.6,
18.5, 18.2, 18.2, 16.7, 16.3, ꢁ1.4, ꢁ3.8, ꢁ4.9 ppm; HRMS (ESI-TOF):
calcd for C61H101NO14Si2Na+ [M+Na+]: 1150.6652; found: 1150.6662.
37: Rf = 0.2 (silica gel, EtOAc:hexanes 2:1); [a]2D5 = ꢁ6.2
(CH3OH, c = 0.13); IR (film): n˜max = 3383, 2955, 2921, 2874, 1698,
1674, 1568, 1555, 1411, 1252, 1170, 1259, 837 cmꢁ1
;
1H NMR
(500 MHz, CD3OD): d = 5.76–5.70 (m, 2H), 5.62 (d, J = 10.5 Hz,
1H), 5.42 (dd, J = 15.5, 7.5 Hz, 1H), 5.21 (br s, 1H), 4.96 (br s, 1H),
4.79–4.77 (m, 2H), 4.59 (d, J = 3.0 Hz, 1H), 4.49–4.45 (m, 1H), 4.29
(br s, 1H), 4.23 (d, J = 6.0 Hz, 1H), 4.20 (dd, J = 10.5, 6.5 Hz, 1H),
4.16–4.15 (m, 1H), 4.10–4.04 (m, 1H), 3.88 (br s, 1H), 3.80 (d, J =
4.0 Hz, 1H), 3.79–3.77 (m, 1H), 3.71 (d, J = 13.0 Hz, 1H), 3.26 (d, J =
13.0 Hz, 1H), 2.79 (q, J = 7.0 Hz, 1H), 2.45 (m, 1H), 2.34–2.26 (m,
3H), 2.24–2.22 (m, 4H), 2.15–2.10 (m, 3H), 2.08–2.05 (m, 1H), 2.03–
1.96 (m, 2H), 1.92 (dd, J = 12.1, 7.7 Hz, 1H), 1.86–1.83 (m, 1H), 1.82–
1.78 (m, 1H), 1.76–1.69 (m, 3H), 1.68–1.63 (m, 2H), 1.62–1.52 (m,
3H), 1.44–1.34 (m, 2H), 1.33–1.28 (m, 4H), 1.05 (d, J = 6.6 Hz, 3H),
1.03 (ddd, J = 9.9, 6.2, 3.0 Hz, 2H), 0.99 (d, J = 7.0 Hz, 3H), 0.96 (t, J =
8.0 Hz, 9H), 0.94(s, 9H), 0.93 (d, J = 7.0 Hz, 3H), 0.90 (d, J = 6.2 Hz,
3H), 0.86 (d, J = 6.6 Hz, 3H), 0.82 (d, J = 5.9 Hz, 3H), 0.62 (q, J =
8.0 Hz, 6H), 0.06 (s, 9H), 0.05 (s, 3H), 0.02 ppm (s, 3H); 13C NMR
(125 MHz, CD3OD): d = 215.6, 181.9, 157.6, 148.2, 133.9, 130.6, 129.4,
123.3, 115.3, 111.2, 107.1, 98.4, 97.8, 80.5, 80.2, 79.6, 78.8, 75.0, 73.4,
72.6, 72.1, 64.1, 50.0, 49.9, 47.0, 42.5, 41.7, 40.3, 38.7, 37.9, 37.6, 35.8,
35.4, 34.6, 34.5, 33.2, 32.9, 32.8, 32.5, 30.82, 30.78, 30.75, 30.5, 26.7,
25.8, 23.6, 20.9, 19.2, 19.1, 18.5, 16.8, 16.6, 7.2, 5.8, ꢁ1.3, ꢁ3.4,
ꢁ4.7 ppm; HRMS (ESI-TOF): calcd for C65H111NO14Na+ [M+Na+]:
1236.7204; found: 1236.7189.
Received: May 17, 2004[Z460696]
Published Online: June 29, 2004
Keywords: degradation studies · natural products · neurotoxins ·
.
structure elucidation · total synthesis
[1] See preceding Communication in this issue: K. C. Nicolaou, S.
Vyskocil, T. V. Koftis, Y. M. A. Yamada, T. Ling, D. Y.-K. Chen,
W. Tang, G. Petrovic, M. O. Frederick, Y. Li, M. Satake, Angew.
Chem. 2004, 116, 4412; Angew. Chem. Int. Ed. 2004, 43, 4312.
[2] M. Satake, K. Ofuji, H. Naoki, K. J. James, A. Fruey, T. McMahon,
J. Silke, T. Yasumoto, J. Am. Chem. Soc. 1998, 120, 9967 – 9968.
[3] K. C. Nicolaou, W. Qian, F. Bernal, N. Uesaka, P. M. Pihko, J.
Hinrichs, Angew. Chem. 2001, 113, 4192 – 4195; Angew. Chem. Int.
Ed. 2001, 40, 4068 – 4071.
[4] A. K. Chatterjee, T.-L. Choi, D. P. Sanders, R. H. Grubbs, J. Am.
Chem. Soc. 2003, 125, 11360 – 11370.
[5] T. Mukaiyama, J. Matsuo, H. Kitagawa, Chem. Lett. 2000, 1250 –
1251.
[6] A modification from the originally reported method
([Pd2dba3]·CHCl3, nBu3P, NaBH4, dioxane, H2O): H. Nakamura,
M. Ono, Y. Shida, H. Akita, Tetrahedron: Asymmetry 2002, 13,
705 – 713.
[7] We thank Prof. Dr. Masayuki Satake for providing us with a
1H NMR spectrum of degradatively derived compound 5 and with
an authentic sample of natural azaspiracid-1.
[8] K. C. Nicolaou, Y. Li, N. Uesaka, T. V. Koftis, S. Vyskocil, T. Ling,
M. Govindasamy, W. Qian, F. Bernal, D. Y.-K. Chen, Angew.
Chem. 2003, 115, 3777 – 3781; Angew. Chem. Int. Ed. 2003, 42,
3643 – 3648.
[9] K. C. Nicolaou, D. Y.-K. Chen, Y. Li, W. Qian, T. Ling, S.
Vyskocil, T. V. Koftis, M. Govindasamy, N. Uesaka, Angew.
Chem. 2003, 115, 3781 – 3783; Angew. Chem. Int. Ed. 2003, 42,
3649 – 3653.
4324
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2004, 43, 4318 –4324