95% yield.16 Reduction with lithium aluminium hydride produced
N-methyltryptamine 4 in 89% yield.16 This intermediate 4 was then
reacted with different 4-substituted bromo acetophenone deriva-
tives to afford the compounds 5a–c.17 Clearly, a wide range of
diverse compounds can be created at this point in the route, which
can be carried out on a large scale without extensive purification.
The coupling of N-methyl tryptamine 4 with 2-bromoacetophe-
none, 2-bromo-4A-chloroacetophenone and 2,4A-dibromoacetophe-
none gave compounds 5a–c in yields between 49 and 61% after
column chromatography. The tertiary amines 5a–c were unstable
after a week when stored at 225 °C, as indicated by NMR. These
materials were reacted separately with methyl p-toluene sulfonate
to furnish the tosylate salts 6a–c. Ion exchange using Dowex® Cl2
138–400 ion exchange resin produced the chloride salts 7a–c in
yields between 46% and 100%.18
The CDK4 activities of fascaplysin 1 and compounds 7a–c were
assayed in vitro, IC50 values (Table 1) were measured for inhibition
of CDK4 using RB-152 fusion protein as a substrate. These results
show that compounds 7a–c are CDK4 active, confirming our
predictions. Furthermore, whilst they fall a little (5-fold or so) short
of the activities expected of a lead compound, they raise the distinct
possibility that potent fascaplysin analogues can be produced in
which the toxicity of fascaplysin has been designed out.
In summary, our strategy to design the first biologically active
non-planar analogues of fascaplysin has proved successful. Com-
pounds 7a–c are active against CDK4, and are likely to pave the
way for more potent non-planar, and by inference non-toxic,
fascaplysin analogues.
This work was supported by Cancer Research UK.
Notes and reference
1 M. E. Wall, M. C. Wani, C. E. Cook, K. H Palmer and H. T. McPhail,
J. Am. Chem. Soc., 1971, 88, 3888; M. E. Wall and M. C. Wani, Chapter
2 in Taxane Anticancer Agents, ACS Symposia Series 583, ACS,
Washington 1995.
2 R. J. B. King, Cancer Biology, Pearson, Harlow, 2nd edn., 2000.
3 L. T. Vassilev, B. T. Vu, B. Graves, D. Carvajal, F. Podlaski, Z.
Filipovic, N. Kong, U. Kammlott, C. Lukacs, C. Klein, N. Fotouhi and
E. A. Liu, Science, 2004, 303, 844.
4 A. Huwe, R. Mazitschek and A. Giannis, Angew. Chem. Int. Ed., 2003,
42, 2122.
5 B. Alberts, A. Johnson, J. Lewis, M. Raff, K. Roberts and P. Walter,
chapter 17 in Molecular Cell Biology, Garland, New York, 4th edn,
2002.
6 W. G. Kaelin, BioEssays, 1999, 21, 950.
7 D. O. Morgan, Nature, 1995, 374, 131.
8 C. McInnes, S. Wang, S. Anderson, J. O’Boyle, W. Jackson, G.
Kontopidis, C. Meades, M. Mezna, M. Thomas, G. Wood, D. P. Lane
and P. M. Fischer, Chem. Biol., 2004, 11, 525.
Fig. 2 Relative positions of fascaplysin 1 (C is in grey, N in cyan, O in
magenta and H in yellow) and compound 7a (C in black, N in blue, O in red
and H in white) when docked into the active site of CDK4. This prediction
concurs with the strategy adopted (Fig. 1).
9 D. M. Roll, C. M. Ireland, H. S. M. Lu and J. Clardy, J. Org. Chem.,
1988, 53, 3276.
10 R. Soni, L. Muller, O. Furet, J. Schoepfer, Ch. Stephan, S. Zumstein-
Mecker, H. Fretz and B. Chaudhuri, Biochem. Biophys. Res. Commun.,
2000, 275, 877.
11 A. Hormann, B. Chaudhuri and H. Fretz, Bioorg. Med. Chem., 2001, 9,
917.
12 A. Sali and T. L. Blundell, J. Mol. Biol., 1993, 234, 779.
13 U. Schulze-Gahmen, H. L. De Bondt and S. H. Kim, J. Med. Chem.,
1996, 39, 4540. PDB, H. M. Berman, J. Westbrook, Z. Feng, G.
Gilliland, T. N. Bhat, H. Weissig, I. N. Shindyalov and P. E. Bourne,
Nucleic Acids Res., 2000, 28, 235; PDB accession code 1hck.
14 D. H. Brotherton, V. Dhanaraj, S. Wick, L. Brizuela, P. J. Domaille, E.
Volyanik, X. Xu, E. Parisini, B. O. Smith, S. J. Archer, M. Serrano, S.
L. Brenner, T. L. Blundell and E. D. Laue, Nature, 1998, 395, 244; PDB
accession code 1blx.
15 G. Jones, P. Willett, R. C. Glen, A. R. Leach and R. Taylor, J. Mol. Biol.,
1997, 267, 727.
16 S. C. Benson, L. Lee, L. Yang and J. K. Snyder, Tetrahedron, 2000, 56,
1165.
Scheme 1 Reagents and conditions. (a) Ethyl choroformate, NaOH 4M,
17 J. Clews, C. J. Cooksey, P. J. Garrat, E. J. Land, C. A. Ramsden and P.
A. Riley, J. Chem. Soc., Perkin Trans.1, 2000, 24, 4306.
18 J. M. Grisar, M. A. Petty, F. N. Bolkenius, J. Dow, J. Wagner, E. R.
Wagner, K. D. Haegele and W. De Jong, J. Med. Chem., 1991, 34,
257.
CHCl3,
3 h, 95%; (b) LiAlH4, THF, N2, reflux, 1 h, 89%; (c)
BrCH2COC6H4R, toluene, N2, NaHCO3, Na2SO4, H2O, 4 h, 49–61%; (d)
methyl-p-toluenesulfonate, acetonitrile, reflux, 4 h, (e) Dowex® Cl2
138–400 ion exchange resin, overnight stirring and column, 46–100%.
C h e m . C o m m u n . , 2 0 0 4 , 1 6 9 6 – 1 6 9 7
1697