A total synthesis of (+)-Goniodiol using an anomeric oxygen-to-carbon rearrangement

Abstract

References

1. B. Talapatra, S. K. Talapatra, D. Basu, T. Deb and S. Goswami, Indian J. Chem., Sect. B, 1985, 24, 29.
2. X.-P. Fang, J. E. Anderson, C.-J. Chang, J. L. McLaughlin and P. E. Fanwick, J. Nat. Prod., 1991, 54, 1034.
3. For example, Y.-C. Wu, C.-Y. Duh, F.-R. Chang, G.-Y. Chang, S.-K. Wang, J.-J. Chang, D. R. McPhail, A. T. McPhail and K.-H. Lee, J. Nat. Prod., 1991, 54, 1077.
4. (a) M. F. Buffet, D. J. Dixon, G. L. Edwards, S. V. Ley and E. W. Tate, Synlett, 1997, 1055; (b) M. F. Buffet, D. J. Dixon, S. V. Ley and E. W. Tate, Synlett, in press; (c) D. J. Dixon, S. V. Ley and E. W. Tate, Synlett, in press.
5. For previous total syntheses of this molecule, see (a) M. Tsubuki, K. Kanai and T. Honda, J. Chem. Soc., Chem. Commun., 1992, 1640; (b) J.-P. Surivet, J. Goré and J.-M. Vatèle, Tetrahedron Lett., 1996, 37, 371; (c) C. Mukai, S. Hirai and M. Hanaoka, J. Org. Chem., 1997, 62, 6619.
6. R. J. K. Taylor, Organocopper Reagents, Oxford University Press, Oxford, 1994, and references cited therein.
7. Direct treatment of the lactol 3 with α-bromoacetophenone in the presence of a variety of bases gave extensive decomposition of the starting material.
8. S. M. Weinreb and S. Nahm, Tetrahedron Lett., 1981, 22, 3815.
9. The configuration of the silyl enol ether was tentatively assigned by analogy with previous work.
10. Typical experimental procedure for the conversion of 4 into 5 and 6: to a stirred solution of 4(410 mg, 0.84 mmol) in CH₂Cl₂(4.0 mL) at 0 °C was added Et₃N (0.17 mL, 1.18 mmol) followed by TMSOTf (0.18 mL, 0.10 mmol). After 30 min the reaction mixture was quenched by the rapid addition of saturated NaHCO₃(aq)(10 mL) and extracted with CH₂Cl₂(3 × 10 mL). Drying (anhydrous Na₂SO₄), filtration and evaporation of the combined organic extracts in vacuo gave the crude TMS enol ether which was dissolved in CH₂Cl₂(1.0 mL) and cooled to –30 °C. To this stirred solution was added TMSOTf (0.015 mL, 0.084 mmol) and after 5 min at –30 °C the reaction mixture was quenched by the addition of saturated NaHCO₃(aq)(5 mL). Extraction with CH₂Cl₂(3 × 10 mL) was followed by drying (anhydrous MgSO₄), filtration and concentration in vacuo, to leave a yellow oil. The product ratio of 5 and 6 was determined to be 1∶1 by the integration of signals at 5.17 (CHOH in 5), and 4.90 (CHOH in 6) in the ¹H NMR (600 MHz; CDCl₃) spectrum of the crude product. Purification of this oil by medium pressure liquid chromatography (MPLC) on a Biotage FLASH 40S column, eluting with 15% ethyl acetate–40/60 petroleum ether isolated 5(179 mg, 44%) and 6(182 mg, 44%) as yellow oils. Selected spectroscopic data for 5: δ_H(600 MHz; CDCl₃): 7.88–7.33 (15H, m, Ph), 5.17 (1H, dd, J 7.1 and 4.2, CHOH), 4.04–4.01 (1H, m, OCH₂CH), 3.89 (1H, dt, J 8.6 and 4.2, CHCHOH), 3.68 (1H, dd, J 10.4 and 6.2, OCHH), 3.63 (1H, d, J 7.1, OH), 3.57 (1H, dd, J 10.4 and 6.7, OCHH), 1.75–1.32 (6H, m, CH₂CH₂CH₂), 1.02 (9H, s, (CH₃)₃Si). Selected spectroscopic data for 6: δ_H(600 MHz; CDCl₃): 7.80–7.33 (15H, m, Ph), 4.90 (1H, dd, J 6.2 and 3.3, CHOH), 3.93–3.90 (1H, m, CHCHOH), 3.86 (1H, m, OCH₂CH), 3.73 (1H, d, J 6.2, OH), 3.46 (1H, dd, J 10.1 and 7.5, OCHH), 3.26 (1H, dd, J 10.1 and 5.3, OCHH), 1.79–1.51 (6H, m, CH₂CH₂CH₂), 0.97 (9H, s, (CH₃)₃Si).
11. S. L. Huang, K. Omura and D. Swern, Synthesis, 1978, 297.
12. For example: J. E. Baldwin, A. K. Forrest, S. Ko and L. N. Sheppard, J. Chem. Soc., Chem. Commun., 1987, 81.
13. L. S. Jeong, R. F. Schinazi, J. W. Beach, H. O. Kim, S. Nampalli, K. Shanmuganathan, A. J. Alves, A. McMillan, C. K. Chu and R. Mathis, J. Med. Chem., 1993, 36, 181.
14. S. V. Ley, J. Norman, W. P. Griffith and S. P. Marsden, Synthesis, 1994, 639.