M. Ngatimin et al. / Tetrahedron Letters 50 (2009) 6008–6011
6011
2007, 48, 8607; For bromination using TBAB with oxidants including BAIB, see
Rho, H. S.; Ko, B.-S.; Kim, H. K.; Ju, Y.-S. Synth. Commun. 2002, 32, 1303;
Ramanarayanan, G. V.; Shukla, V. G.; Akamanchi, K. G. Synlett 2002, 2059.
9. (a) Johnson, C. R.; Adams, J. P.; Braun, M. P.; Senanayake, C. B. W.; Wovkulich, P.
M.; Uskokovic, M. R. Tetrahedron Lett. 1992, 33, 917; For a recent example, see
(b) Kim, J. M.; Na, J. E.; Kim, J. N. Tetrahedron Lett. 2003, 44, 6317; For a review
on iodination covering enones, see: (c) Stavber, S.; Jereb, M.; Zupan, M.
Synthesis 2008, 1487.
10. (a) Dieter, R. K.; Nice, L. E.; Velu, S. E. Tetrahedron Lett. 1996, 37, 2377; (b) Kim,
K.-M.; Park, I.-H. Synthesis 2004, 16, 2641; (c) Schulze, A.; Pagona, G.; Giannis,
A. Synth. Commun. 2006, 36, 1147; (d) Kim, K. M.; Chung, K. H.; Kim, J. N.; Ryu,
E. K. Synthesis 1993, 283; (e) Righi, G.; Bovicelli, P.; Sperandio, A. Tetrahedron
Lett. 1999, 40, 5889; (f) Ley, S. V.; Whittle, A. J. Tetrahedron Lett. 1981, 34, 3301;
(g) Kamigata, N.; Satoh, T.; Yoshida, M. Bull. Chem. Soc. Jpn. 1988, 61, 449.
11. Rho, H. S.; Ko, B.-S.; Ju, Y.-S. Synth. Commun. 2001, 31, 2101.
12. A magnetically stirred solution of cyclohexen-2-one (51.2 mg, 0.518 mmol) in
CH2Cl2 (4 mL) was treated with BAIB (193.8 mg, 0.60 mmol) and pyridineꢁHCl
(145 mg, 1.25 mmol). The solution was stirred for 6 h at which point the
starting enone had been consumed as judged by TLC analysis. The reaction
mixture was diluted with CH2Cl2 (5 mL), then, washed with HCl (10 mL of a
1 M solution). The aqueous phase was extracted with CH2Cl2 (2 ꢂ 5 mL) and
the combined organic extracts washed with brine (5 mL), dried (MgSO4),
filtered, and concentrated in vacuo to afford a yellow oil that was subjected to
flash column chromatography (silica gel, 1:4 v/v ethyl acetate/hexanes) and,
upon collection and evaporation of the appropriate fractions (Rf 0.2) gave 6b
(61.2 mg, 91%) the 1H NMR and 13C NMR data of which matched those reported
in the literature.10a
Acknowledgements
We acknowledge the financial support of the Australian Re-
search Council through the Discovery program, (DP0881137) and
Monash University through the Early Career Researcher program.
The support of Roche Palo Alto through the donation of equipment
is also gratefully acknowledged.
References and notes
1. Amagata, T.; Minoura, K.; Numata, A. J. Nat. Prod. 2006, 69, 1384; For the
structurally related isariotins, see: Haritakun, R.; Srikitikulchai, P.;
Khoyaiklang, P.; Isaka, M. J. Nat. Prod. 2007, 70, 1478.
2. Wipf, P.; Kim, Y.; Fritch, P. C. J. Org. Chem. 1993, 58, 7195; For a recent oxidative
dearomatization, see: Tang, B.-X.; Tang, D.-J.; Tang, S.; Yu, F.; Zhang, Y.-H.;
Liang, Y.; Zhong, P.; Li, J.-H. Org. Lett. 2008, 10, 1063.
3. Compound 5a was prepared using an approach analogous to: (a) Schinzer, D.;
Solyom, S.; Becker, M. Tetrahedron Lett. 1985, 26, 1831; (b) Banwell, M. G.;
Lupton, D. W.; Willis, A. C. Aust. J. Chem. 2005, 58, 722. using as the key step a
Stork–Danheiser alkylation; (c) Stork, G.; Danheiser, R. L. J. Org. Chem. 1973, 38,
1775.
4. Chandrasekhar, S.; Mohanty, P. K.; Takhi, M. J. Org. Chem. 1997, 62, 2628; For
another one-pot desilyation–oxidation, see: Karimi, B.; Rajabi, J. Org. Lett. 2004,
6, 2841.
5. In other studies directed towards the synthesis of the gymnastatins it has been
observed that the deprotected form of compound 5a is unstable. These studies
will be reported in due course.
13. Prepared by alkylation of the corresponding amine: Gribov, D. V.; Hultzsch, K.
C. Angew. Chem., Int. Ed. 2004, 43, 5542.
14. For a recent dichlorination in synthesis, see: Shibuya, G. M.; Kanady, J. S.;
Vanderwal, C. D. J. Am. Chem. Soc. 2008, 130, 12514. and references therein; For
the use of PhI(Cl)2, see: Shellhamer, D. P.; Ragains, M. L.; Gipe, B. T.; Heasley, V.
L. J. Fluorine Chem. 1982, 20, 13.
15. Although enantioslective monohalogenations (specifically fluorinations) have
been investigated, see: Ibrahim, H.; Togni, A. Chem. Commun. 2004, 1147. The
chlorinations are yet to be reported.
16. For preliminary work, see: Ochiai, M.; Kitagawa, Y.; Takayama, N.; Takaoka, Y.;
Motoo, S. J. Am. Chem. Soc. 1999, 121, 9233; For recent advances, see: Dohi, T.;
Maruyama, A.; Takenaga, N.; Senami, K.; Minamitsuji, Y.; Fujioka, H.;
Caemmerer, S. B.; Kita, Y. Angew. Chem., Int. Ed. 2008, 47, 3787. For a recent
review of I[III] chemistry, see: Ref. 6c.
6. (a) De Mico, A.; Margarita, R.; Parlanti, L.; Vescovi, A.; Piancatelli, G. J. Org.
Chem. 1997, 62, 6974; For a recent example of the use of BAIB in the oxidation
of alcohols, see: (b) Karimipour, G. R.; Shadegan, H. A.; Ahmadpour, R. J. Chem.
Res. 2007, 4, 252; For a review of the use of polyvalent iodine in organic
synthesis see: (c) Zhdankin, V. V.; Stang, P. J. Chem. Rev. 2008, 108, 5299.
7. 4-(3-(tert-Butyldimethylsilyloxy)propyl)-2-chlorocyclohex-2-enone 6a 1H
NMR (500 MHz, CDCl3) d 7.04 (dd, J = 3.0 and 1.5 Hz, 1H), 3.64 (t, J = 6.0 Hz,
2H), 2.70 (dt, J = 17.0 and 5.0 Hz, 1H), 2.64–2.55 (m, 1H), 2.54–2.44 (m, 1H),
2.19–2.10 (m, 1H), 1.80–1.70 (m, 1H), 1.66–1.48 (m, 4H), 0.89 (s, 9H), 0.04 (s,
6H); 13C NMR (125 MHz) 151.2, 131.9, 62.9, 38.1, 37.5, 31.2, 30.2, 28.7, 26.2,
18.6, -5.1; m ;
max 2953, 2930, 2858, 1702, 1605, 1472, 1463, 1256, 836, 777 cmꢀ1
HRMS (ESI) Found (M+Na+), 325.1366 C15H27ClO2Si requires (M+Na)+ 325.1367.
8. For typical procedures, see: (a) Smith, A. B.; Branca, S. J.; Pilla, N. N.; Guaciaro,
M. A. J. Org. Chem. 1982, 47, 1855; For a recent example, see: (b) Bovonsombat,
P.; Rujiwarangkul, P.; Bowornkiengkai, T.; Leykajarakul, J. Tetrahedron Lett.
17. Boppisetti, J. K.; Birman, V. B. Org. Lett. 2009, 11, 1221.
18. Prepared using a modification of Tani, K.; Behenna, D. C.; McFadden, R. M.;
Stoltz, B. M. Org. Lett. 2007, 9, 2529.
19. Enantiomeric excess determined by HPLC using a Daicel OD-H chiral column.