4 D. P. Curran and Z. Luo, J. Am. Chem. Soc., 1999, 121, 9069.
5 For excellent reviews, see: (a) C. V. Galliford and K. A. Scheidt, Angew.
Chem., Int. Ed., 2007, 46, 8748; (b) C. Marti and E. M. Carreira,
Eur. J. Org. Chem., 2003, 2209; (c) B. M. Trost and M. K. Brennan,
Synthesis, 2009, 3003.
11 (a) L. A. McAllister, R. A. McCormick, S. Brand and D. J. Procter,
Angew. Chem. Int. Ed., 2005, 44, 452; (b) L. A. McAllister, R. A.
McCormick, K. M. James, S. Brand, N. Willetts and D. J. Procter,
Chem. Eur J., 2007, 13, 1032; (c) K. M. James, N. Willetts and D. J.
Procter, Org. Lett., 2008, 10, 1203; (d) C. Ovens, J. C. Vogel, N. G.
Martin and D. J. Procter, Chem. Commun., 2009, 3101.
6 For syntheses of spirotryprostatin A and B, see: (a) S. D. Edmondson
and S. J. Danishefsky, Angew. Chem. Int. Ed., 1998, 37, 1138; (b) S. D.
Edmondson, S. J. Danishefsky, L. Sepp-Lorenzino and N. Rosen, J. Am.
Chem. Soc., 1999, 121, 2147; (c) F. von Nussbaum and S. J. Danishefsky,
Angew. Chem. Int. Ed., 2000, 39, 2175; (d) P. R. Sebahar and R. M.
Williams, J. Am. Chem. Soc., 2000, 122, 5666; (e) L. E. Overman and
M. D. Rosen, Angew. Chem. Int. Ed., 2000, 39, 4596; (f) H. Wang and
A. Ganesan, J. Org. Chem., 2000, 65, 4685; (g) P. R. Sebahar, H. Osada,
T. Usui and R. M. Williams, Tetrahedron, 2002, 58, 6311; (h) C. Meyers
and E. M. Carreira, Angew. Chem. Int. Ed., 2003, 42, 694; (i) F. Y.
Miyake, K. Yakushijin and D. A. Horne, Angew. Chem. Int. Ed., 2004,
43, 5357; (j) C. Marti and E. M. Carreira, J. Am. Chem. Soc., 2005, 127,
11505; (k) B. M. Trost and D. T. Stiles, Org. Lett., 2007, 9, 2763.
7 For selected examples, see: (a) M. M.-C. Lo, C. S. Neumann, S.
Nagayama, E. O. Perlstein and S. L. Schreiber, J. Am. Chem. Soc.,
2004, 126, 16077; (b) K. Ding, Y. Lu, Z. Nikolovska-Coleska, S. Qiu,
Y. Ding, W. Gao, J. Stuckey, K. Krajewski, P. P. Roller, Y. Tomita, D. A.
Parrish, J. R. Deschamps and S. Wang, J. Am. Chem. Soc., 2005, 127,
10130; (c) S. Shangary, D. Qin, D. McEachern, M. Liu, R. S. Miller, S.
Qiu, Z. Nikolovska-Coleska, K. Ding, G. Wang, J. Chen, D. Bernard,
J. Zhang, Y. Lu, Q. Gu, R. B. Shah, K. J. Pienta, X. Ling, S. Kang, M.
Guo, Y. Sun, D. Yang and S. Wang, Proc. Natl. Acad. Sci. USA, 2008,
105, 3933; (d) S. Yu, D. Qin, S. Shangary, J. Chen, G. Wang, K. Ding,
D. McEachern, S. Qiu, Z. Nikolovska-Coleska, R. Miller, S. Kang, D.
Yang and S. Wang, J. Med. Chem., 2009, 52, 7970.
12 For cleavage of an analogous linker in solid-phase synthesis, see:
(a) L. A. McAllister, S. Brand, R. de Gentile and D. J. Procter, Chem.
Commun., 2003, 2380; (b) K. L. Turner, T. M. Baker, S. Islam, D. J.
Procter and M. Stefaniak, Org. Lett., 2006, 8, 329; (c) L. A. McAllister,
K. L. Turner, S. Brand, M. Stefaniak and D. J. Procter, J. Org. Chem.,
2006, 71, 6497. For a review of sulfur and selenium linkers in phase
tag-assisted synthesis, see: L. A. McAllister, R. A. McCormick and
D. J. Procter, Tetrahedron, 2005, 61, 11527.
13 For a review of the chemistry of Sm(III) enolates, see: I. M. Rudkin,
L. C. Miller and D. J. Procter, Organometallic Chemistry, 2008, 34,
19.
14 (a) P. B. Alper, C. Meyers, A. Lerchner, D. R. Siegel and E. M. Carreira,
Angew. Chem. Int. Ed. Engl., 1999, 38, 3186; (b) A. Lerchner and
E. M. Carreira, J. Am. Chem. Soc., 2002, 124, 14826; (c) A. Lerchner
and E. M. Carreira, Chem. –Eur. J., 2006, 12, 8208. See also ref. 6h
and 6j.
15 See the Supporting Information for CCDC numbers and X-ray
crystallographic data†.
16 The ratio of the product diastereoisomers 19a and 19b remains constant
throughout the course of the reaction, suggesting epimerisation at
the quaternary stereocentre in the products is not taking place.
The epimerisation of pyrrolidinyl–spirooxindoles through a retro–
Mannich/Mannich pathway is well known. See ref. 6j and references
therein.
8 J. Yoshida and K. Itami, Chem. Rev., 2002, 102, 3693.
17 Carreira obtained several diastereoisomers from his stepwise cyclisa-
tion process in a ratio of 8 : 1 : 8 (major : minor : other diastereoisomers).
Epimerisation gave improved ratios of 5 : 1 to 7 : 1. See ref. 6j.
18 See the Supporting Information for details of the recycling of the
fluorous thiol†.
9 For reviews on the Pummerer reaction, see: (a) S. K. Bur and A. Padwa,
Chem. Rev., 2004, 104, 2401; (b) K. S. Feldman, Tetrahedron, 2006, 62,
5003; (c) S. Akai and Y. Kita, Top. Curr. Chem., 2007, 274, 35; (d) L. H. S.
Smith, S. C. Coote, H. F. Sneddon and D. J. Procter, Angew. Chem. Int.
Ed., 2010, 49, 5832.
10 (a) M. Miller, W. Tsang, A. Merritt and D. J. Procter, Chem. Commun.,
2007, 498; (b) M. Miller, J. C. Vogel, W. Tsang, A. Merrit and D. J.
Procter, Org. Biomol. Chem., 2009, 7, 589; (c) C. Ovens, N. G. Martin
and D. J. Procter, Org. Lett., 2008, 10, 1441.
19 For an example of the use of the BnF protection on nitrogen, see: S.
Werner and D. P. Curran, Org. Lett., 2003, 5, 3293.
20 MTT assays assessing cytotoxicity in MDA-468 cells. Spirotryprostatin
A (110 mM ref. 6b), 36 (95 mM). The synthesis and biological evaluation
of more active spirooxindoles is currently underway.
5108 | Org. Biomol. Chem., 2011, 9, 5104–5108
This journal is
The Royal Society of Chemistry 2011
©