674
LETTERS
SYNLETT
References and Notes
1.
a) Balkenhohl, F.; von dem Bussche-Hünnefeld, C.; Lansky, A.;
Zechel, C. Angew. Chem., Int. Ed. Engl. 1996, 35, 2288. b)
Hermkens, P.H.H.; Ottenheijm, H.C.J.; Rees, D. Tetrahedron
1996, 52, 4527. c) Gallop, M.A.; Barrett, R.W.; Dower, W.J.;
Foder, S.P.A.; Gordon, E.M. J. Med. Chem. 1994, 37, 1233. d)
Gordon, E.M.; Barrett, R.W.; Dower, W.J.; Foder, S.P.A.; Gallop,
M.A. J. Med. Chem. 1994, 37, 1385.
2.
For Stille couplings see: a) Forman, F.W.; Sucholeiki, I. J. Org.
Chem. 1995, 60, 523. b) Plunkett, M.J.; Ellman, J.A. J. Am. Chem.
Soc. 1995, 117, 3306. c) Deshpande, M.S. Tetrahedron Lett. 1994,
35, 5613. For Suzuki couplings see: d) Frenette, R.; Friesen, R.W.
Tetrahedron Lett. 1994, 35, 9177. e) Backes, B.J.; Ellman, J.A. J.
Am. Chem. Soc. 1994, 116, 11171. f) Piettre, S.R.; Baltzer, S.
Tetrahedron Lett. 1997, 38, 1197. g) Yoo, S.; Seo, J.; Yi, K., Gong,
Y. Tetrahedron Lett. 1997, 38, 1203. For Heck reactions see: h)
Yu, K.-L.; Deshpande, M.S.; Dolatrai, M.V. Tetrahedron Lett.
1994, 35, 8919. i) Hiroshige, M.; Hauske, J.R.; Zhou, P.
Tetrahedron Lett. 1995, 36, 4567. j) For others see: Young, K.Y.;
Nelson, J.C.; Moore, J.S. J. Am. Chem. Soc. 1994, 116, 10841. For
use of polymer bound Pd-catalyst see: k) Jang, S.-B. Tetrahedron
Lett. 1997, 38, 1793.
3.
In most examples (reference 2) much more reactive electron poor
aromatic halides are used in the Pd-coupling reactions.
4.
5.
Manuscripts in preparation.
Polystyrene beads, cross-linked with 1% divinyl benzene were
used for all experiments; functionalization was approximately 0.7
mmol/g.
6.
7.
Rink, H. Tetrahedron Lett. 1987, 28, 3787.
Miyaura, N.; Yanagi, T.; Suzuki, A. Synth. Commun. 1981, 11,
513.
8.
9.
Wallow, T.I.; Novak, B.M. J. Org. Chem. 1994, 59, 5034.
Beller, M.; Fischer, H.; Herrmann, W.A.; Öfele, K.; Brossmer, C.
Angew. Chem., Int. Ed. Eng. 1995, 34, 1848.
10. Double couplings imply complete removal of all reagents and side
products through washing of the resin before submitting it under
identical coupling conditions for a second time. If the washing
step is avoided, no significantly increased yields were observed,
presumably due to accumulation of catalyst poisoning side
products.
11. a) Sato, M; Miyaura, N.; Suzuki, A. Chem. Lett. 1989, 1405. b)
Watanabe, T.; Miyaura, N.; Suzuki, A. Synlett 1992, 3, 207.
12. Miyaura, N.; Ishiyama, T.; Sasaki, H.; Ishikawa, M.; Satoh, M.;
Suzuki, A. J. Am. Chem. Soc. 1989, 111, 314.
13. Wright, S.W.; Hageman, D.L.; McClure, L.D. J. Org. Chem. 1994,
59, 6095.
14. Representative protocol for the Suzuki-coupling on the solid
phase: To resin 5 (0.4 g, 0.205 mmol) were added freshly distilled
dioxane (3.5 ml,), p-trifluoromethylbenzene boronic acid (156
mg, 0.820 mmol) and K CO (138 mg, 1.85 mmol) dissolved in
2
3
H O (0.56 ml) and the resulting suspension was degassed with
2
argon for 20 min. Pd(OAc) (5 mg, 0.02 mmol) was added at once
2
and the reaction was shaken at 100°C for 24h. The solid phase was
filtered and washed with 5 ml each of dioxane (6 x), H O (6 x),
2
EtOH:H O (1:1, 3 x), EtOH (3 x) and Et O (3 x). The resin was
2
2
dried under high vacuum and suspended in dioxane (6.6 ml).
Sodium (28 mg, 1.23 mmol) was dissolved in MeOH (1.6 ml) and
the resulting solution of NaOMe was added. The reaction mixture
was shaken for 24h at RT. The resin was filtered off and further