of methoxycarbonyl group and a p-Claisen rearrangement
serve as the key steps for the total synthesis of clausamine C
and clausevatine D. The developed route has been successfully
implemented in the first total synthesis of clausine F and
clausamine D. Further extension of this strategy to the
asymmetric synthesis of clausevatine D and furanoclausamines
is underway.
(b) H.-J. Knolker, Chem. Lett., 2009, 38, 8–13; (c) S. Agarwal,
¨
S. Cammerer, S. Filali, W. Frohner, J. Knoll, M. P. Krahl,
K. R. Reddy and H.-J. Knolker, Curr. Org. Chem., 2005, 9,
1601–1614.
¨
7 D. Mal, B. K. Senapati and P. Pahari, Tetrahedron, 2007, 63,
3768–3781.
8 (a) M. R. Naffziger, B. O. Ashburn, J. R. Perkins and R. G. Carter,
J. Org. Chem., 2007, 72, 9857–9865; (b) T. P. Lebold and
M. A. Kerr, Org. Lett., 2008, 10, 997–1000; (c) T. P. Lebold and
M. A. Kerr, Org. Lett., 2007, 9, 1883–1886; (d) R. Forke,
This work was supported by the Council of Scientific and
Industrial Research, New Delhi. A. K. J. is grateful to the
UGC, New Delhi for his research fellowship. The authors are
thankful to FIST program of DST, New Delhi, for providing
NMR facilities.
M. P. Krahl, T. Krause, G. Schlechtingen and H.-J. Kno
Synlett, 2007, 268–272; (e) M. P. Krahl, A. Jager, T. Krause and
H.-J. Knolker, Org. Biomol. Chem., 2006, 4, 3215–3219;
¨
lker,
¨
(f) H.-J. Knolker and F. Wolfgang, Synlett, 1997, 1108–1110;
¨
(g) H.-J. Knolker, W. Frohner and A. Wagner, Tetrahedron Lett.,
¨
¨
1998, 39, 2947–2950; (h) H.-J. Knolker and K. R. Reddy, Synlett,
¨
1999, 596–598; (i) H.-J. Knolker, E. Baum and K. R. Reddy,
Notes and references
¨
Tetrahedron Lett., 2000, 41, 1171–1174; (j) R. Czerwonka,
1 (a) H.-J. Knolker and K. R. Reddy, Chem. Rev., 2002, 102,
¨
4303–4427; (b) D. P. Chakraborty, in The Alkaloids, ed.
K. R. Reddy, E. Baum and H.-J. Knolker, Chem. Commun.,
¨
¨
2006, 711–713; (k) W. Frohner, K. R. Reddy and H.-J. Knolker,
G. A. Cordell, Academic Press, New York, 1993, vol. 44, p. 257,
and references therein; (c) H.-J. Knolker, Curr. Org. Synth., 2004,
Heterocycles, 2007, 74, 895–912.
9 C. Ito, S. Katsuno, N. Ruangrungsi and H. Furukawa, Chem.
Pharm. Bull., 1998, 46, 344–346.
10 C. Ito, S. Katsuno, M. Itoigawa, N. Ruangrungsi, T. Mukainaka,
M. Okuda, Y. Kitagawa, H. Tokuda, H. Nishino and
H. Furukawa, J. Nat. Prod., 2000, 63, 125–128.
11 C. Ito, M. Itoigawa, A. Sato, C. M. Hasan, M. A. Rashid,
H. Tokuda, T. Mukainaka, H. Nishino and H. Furukawa,
J. Nat. Prod., 2004, 67, 1488–1491.
¨
1, 309–331; (d) H.-J. Knolker, Top. Curr. Chem., 2005, 244,
¨
115–148; (e) H.-J. Knolker and K. R. Reddy, in The Alkaloids,
¨
ed. G. A. Cordell, Academic Press, Amsterdam, 2008, vol. 65,
pp. 1–430.
2 Organic Light Emitting Devices: Synthesis, Properties, and
Applications, ed. K. Mullen and U. Scherf, Wiley-VCH, Weinheim,
Germany, 2006.
¨
3 (a) D. Crich and S. Rumthao, Tetrahedron, 2004, 60, 1513–1516;
(b) H.-Y. Cheng, C. S. Randall, W. W. Holl, P. P. Constantinides,
T.-L. Yue and G. Z. Feuerstein, Biochim. Biophys. Acta,
Biomembr., 1996, 1284, 20–28; (c) R. Kumar, U. Ramachandran,
K. Srinivasan, P. Ramarao, S. Raichur and R. Chakrabarti,
Bioorg. Med. Chem., 2005, 13, 4279–4290.
4 (a) L. Ackermann and A. Althammer, Angew. Chem., Int. Ed.,
2007, 46, 1627–1629; (b) J. A. Jordan-Hore, C. C. C. Johansson,
M. Gulias, E. M. Beck and M. J. Gaunt, J. Am. Chem. Soc., 2008,
130, 16184–16186; (c) K. E. Knott, S. Auschill, A. Jager and
12 (a) N. J. P. Broom and P. G. Sammes, J. Chem. Soc., Chem.
Commun., 1978, 162–164; (b) D. Mal and P. Pahari, Chem. Rev.,
2007, 107, 1892–1918.
13 (a) J. J. Sperry, T. Y. Yuen and M. A. Brimble, Synthesis, 2009,
2561–2569; (b) N. P. H. Tan and C. D. Donner, Tetrahedron Lett.,
2008, 49, 4160–4162.
14 Mitsunobu etherification of carbazole 26 with prenyl alcohol was
unsuccessful.
15 (a) X. Lei, M. Dai, Z. Hua and S. J. Danishefsky, Tetrahedron
Lett., 2008, 49, 6383–6385; (b) A. S. R. Anjaneyulu and B. M. lsaa,
J. Chem. Soc., Perkin Trans. 1, 1991, 2089–2094; (c) A. M. Martin
Castro, Chem. Rev., 2004, 104, 2939–3002.
16 D. Mal, A. Jana, S. Ray, S. Bhattacharya, A. Patra and S. R. De,
Synth. Commun., 2008, 38, 3937–3946.
17 The established methods for N-debenzylation such as
O2-KTB- DMSO, AlCl3 and TFA-TfOH did not work out. With
O2-KTB-DMSO, the corresponding carboxylic acid was obtained
in 69% yield.
H.-J.
Kno
¨
lker,
Chem.
Commun.,
2009,
1467–1469;
(d) M. E. Buden, V. A. Vaillard, S. E. Martin and R. A. Rossi,
J. Org. Chem., 2009, 74, 4490–4498; (e) M. Hussain, D. T. Tung
and P. Langer, Synlett, 2009, 1822–1826; (f) T. Watanabe, S. Oishi,
N. Fujii and H. Ohno, J. Org. Chem., 2009, 74, 4720–4726; (g) K.
1. Thevissen, A. Marchand, P. Chaltin, E. M. K. Meert and B. P.
A. Cammue, Curr. Med. Chem., 2009, 16, 2205–2211;
(h) V. Sridharan, M. A. Martin and J. C. Menendez, Eur. J.
Org. Chem., 2009, 4614–4621.
18 For the N-debenzylation of 28, the standard reagents: (i) NBS,
NMA, (ii) CAN, (iii) IBX, (iv) ClCO2Et, (v) Me3SiCl and NaI, (vi)
BF3ÁOEt2, (vii) diisopropyl azodicarboxylate in toluene, (viii) H2,
10% Pd–C, (ix) Li, C10H8, (x) Na/ liq. NH3 failed to afford the
desired product i.e. N-debenzylated analog of 28.
19 T.-S. Wu and S.-C. Huang, Chem. Pharm. Bull., 1992, 40,
1069–1071.
5 (a) W. Q. Kong, C. L. Fu and S. M. Ma, Chem. Commun., 2009,
4572–4574; (b) C. Ito, M. Itoigawa, K. Aizawa, K. Yoshida,
N. Ruangrungsi and H. Furukawa, J. Nat. Prod., 2009, 72,
1202–1204; (c) S. Tohyama, T. Choshi, S. Azuma, H. Fujioka
and S. Hibino, Heterocycles, 2009, 79, 955–965; (d) N. Ramesh,
G. G. Rajeshwaran and A. K. Mohanakrishnan, Tetrahedron,
2009, 65, 3592–3602; (e) C. N. Della, G. Sassi and M. Catellani,
Adv. Synth. Catal., 2008, 350, 2179–2182; (f) W. C. P. Tsang,
R. H. Munday, G. Brasche, N. Zheng and S. L. Buchwald, J. Org.
Chem., 2008, 73, 7603–7610; (g) J. T. Kuethe and K. G. Childers,
Adv. Synth. Catal., 2008, 350, 1577–1586; (h) Z. J. Liu and
R. C. Larock, Tetrahedron, 2007, 63, 347–355.
20 T.-S. Wu, S.-C. Huang and P.-L. Wu, Chem. Pharm. Bull., 1998,
46, 1459–1461.
21 H. Hamamoto, Y. Suzuki, H. Takahashi and S. Ikegam, Adv.
Synth. Catal., 2007, 349, 2685–2689.
22 (a) Q. Lin, H. Xu, B. Wu, G. Guo and W. Zhou, Tetrahedron Lett.,
1985, 26, 1233–1236; (b) M. Ochiai, T. Ukita, S. Iwaki, Y. Nagao
and E. Fujita, J. Org. Chem., 1989, 54, 4832–4840.
6 (a) J. S. Russel, E. T. Pelkey and S. J. P. Yoon-Miller, Progress in
Heterocyclic Chemistry, 2009, vol. 21, pp. 145–178;
ꢀc
This journal is The Royal Society of Chemistry 2010
Chem. Commun., 2010, 46, 4411–4413 | 4413