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Hypervalent Iodine Reagents in Organic Synthesis

Hypervalent Iodine Reagents in Organic Synthesis. Andrew T. Parsons March 23, 2007. Outline. Background Iodine(III) reagents Iodine(V) reagents Conclusions. Hypervalent Iodine: An Introduction.

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Hypervalent Iodine Reagents in Organic Synthesis

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  1. Hypervalent Iodine Reagents in Organic Synthesis Andrew T. Parsons March 23, 2007

  2. Outline • Background • Iodine(III) reagents • Iodine(V) reagents • Conclusions

  3. Hypervalent Iodine: An Introduction • Hypervalent iodine: Species that exceed eight electrons in the valence shell, typically IIII and IV • Can accommodate up to 12 valence electrons: • Species with 10 valence electrons are more common: Zhdankin, V. V.; Stang, P. J. Chem. Rev. 2002,102, 2523-2584.

  4. Hypervalent Iodine: A Brief History • Both Iodine(III) and (V) compounds were first prepared by Willgerodt in 1886 and 1900, respectively • Iodine(III) compounds are referred to as λ3-iodanes • Iodine(V) compounds are referred to as λ5-iodanes, periodanes, or periodinanes Stang, P. J.; Zhdankin, V. V. Chem. Rev. 1996,96, 1123-1178.

  5. Structural Characteristics • λ3-iodanes: • λ5-iodanes: Stang, P. J.; Zhdankin, V. V. Chem. Rev. 1996,96, 1123-1178.

  6. Outline • Background • Iodine(III) reagents • Iodine(V) reagents • Conclusions

  7. Preparation of IIII Reagents • Most reagents are prepared directly from iodobenzene: Varvoglis, A. Tetrahedron 1997,53, 1179-1255.

  8. Reactions of Iodine(III) Compounds • Reactivity is driven by the electrophilic nature of IIII • Typical reactions proceed through an initial nucleophilic attack of the iodine center: • PhIX is an excellent leaving group, on the order of 106 better than –OTf, and therefore substitutions and reductive eliminations are prevalent

  9. Reactions of Iodine(III) Compounds: Oxygenations

  10. Reactions of Iodine(III) Compounds: Oxygenations • Iodosylbenzene, PhIO: • Useful for a number of different oxidations • Exists as a polymer, which is activated through depolymerization when treated with alcoholic solvents and base • Can also be activated in the presence of a Lewis acid or Br - catalyst • The active IIII species, PhI(OMe)2, can also be generated from PhI(OAc)2 Moriarty, R. M.; Hu, H.; Gupta, S. C. Tetrahedron Lett. 1981,22, 1283. Moriarty, R. M. J. Org. Chem. 2005,70, 2893-2903.

  11. Oxidations with Iodosylbenzene • Useful in the α-hydroxylation of ketones • α-Hydroxylation of ketones can be carried out using CrO3, typically with higher yields • PhIO is a non-toxic alternative to CrVI Moriarty, R. M.; Gupta, S. C.; Hu, H.; Berenschot, D. R.; White, K. B. J. Am. Chem. Soc. 1981,103, 686-688. Moriarty, R. M.; Hu, H.; Gupta, S. C. Tetrahedron Lett. 1981,22, 1283.

  12. Oxidations with Iodosylbenzene Moriarty, R. M.; Hu, H.; Gupta, S. C. Tetrahedron Lett. 1981,22, 1283.

  13. Mechanism of α-Hydroxylation Moriarty, R. M. J. Org. Chem. 2005,70, 2893-2903.

  14. Applications in Total Synthesis • Synthesis of (-)-Xialenon • Carrying out this transformation using a Rubottom oxidation provided a dr of 3:1 Hodgson, D. M.; Galano, J.-M.; Christlieb, M. Tetrahedron 2003,59, 9719-9728. Rubottom, G.M.; Gruber, J.M. J. Org. Chem. 1978, 43, 1599-1602

  15. Catalytic α-Acetoxylation of Ketones Ochiai, M.; Takeuchi, Y.; Katayama, T.; Sueda, T.; Miyamoto, K. J. Am. Chem. Soc. 2005,127, 12244-12245.

  16. Catalytic Cycle Ochiai, M.; Takeuchi, Y.; Katayama, T.; Sueda, T.; Miyamoto, K. J. Am. Chem. Soc. 2005,127, 12244-12245.

  17. Oxidative Rearrangements of Aryl Alkenes • Koser’s reagent induces an oxidative rearrangement of aryl alkenes to afford α-aryl ketones Justik, M. W.; Koser, G. F. Tetrahedron Lett. 2004,45, 6159-6163.

  18. Oxidative Rearrangements of Aryl Alkenes Justik, M. W.; Koser, G. F. Tetrahedron Lett. 2004,45, 6159-6163.

  19. Oxidative Rearrangements of Aryl Alkenes Justik, M. W.; Koser, G. F. Tetrahedron Lett. 2004,45, 6159-6163.

  20. Oxidative Cleavage of Alkenes • Works well for electron-rich olefins • Reaction times typically 0.5-5 h • Safer than ozonolysis, cheaper than transition-metal reagents Miyamoto, K.; Tada, N.; Ochiai, M. J. Am. Chem. Soc. 2007,129, 2772-2773.

  21. Oxidative Cleavage of Alkenes Miyamoto, K.; Tada, N.; Ochiai, M. J. Am. Chem. Soc. 2007,129, 2772-2773.

  22. Oxidative Cleavage of Alkenes • Suggests that an epoxidation precedes cleavage Miyamoto, K.; Tada, N.; Ochiai, M. J. Am. Chem. Soc. 2007,129, 2772-2773. Moriarty, R. M.; Gupta, S. C.; Hu, H.; Berenschot, D. R.; White, K. B. J. Am. Chem. Soc. 1981,103, 686-688.

  23. Oxidative Cleavage of Alkenes • Suggests that an epoxidation precedes cleavage Miyamoto, K.; Tada, N.; Ochiai, M. J. Am. Chem. Soc. 2007,129, 2772-2773.

  24. Reactions of Iodine(III) Compounds: Oxidation of Phenols • Previously: Stang, P. J.; Zhdankin, V. V. Chem. Rev. 1996,96, 1123-1178.

  25. Application to Spirocyclizations • Tether a nucleophile to the phenol: • Possible applications in natural product synthesis

  26. Spirocyclization of Phenols: Early Studies Tamura, Y.; Yakura, T.; Haruta, J.-I.; Kita, Y. J. Org. Chem. 1987,52, 3927-3930.

  27. Mechanism Tamura, Y.; Yakura, T.; Haruta, J.-I.; Kita, Y. J. Org. Chem. 1987,52, 3927-3930.

  28. Current Standard: Catalytic Spirocyclizations Dohi, T.; Maruyama, A.; Yoshimura, M.; Morimoto, K.; Tohma, H.; Kita, Y. Angew. Chem. Int. Ed. 2005,44, 6192-6196.

  29. Catalytic Cycle Dohi, T.; Maruyama, A.; Yoshimura, M.; Morimoto, K.; Tohma, H.; Kita, Y. Angew. Chem. Int. Ed. 2005,44, 6192-6196.

  30. Applications in Total Synthesis • Synthesis of Aranorosin: Wipf, P.; Kim, Y.; Fritch, P. C. J. Org. Chem. 1993,58, 7195-7203.

  31. PhI(OCOCF3)2-Promoted Formation of Lactols Kita, Y.; Matsuda, S.; Fujii, E.; Horai, M.; Hata, K.; Fujioka, H. Angew. Chem. Int. Ed. 2005,44, 5857-5860.

  32. PhI(OCOCF3)2-Promoted Formation of Lactols Kita, Y.; Matsuda, S.; Fujii, E.; Horai, M.; Hata, K.; Fujioka, H. Angew. Chem. Int. Ed. 2005,44, 5857-5860.

  33. Applications in Total Synthesis • Synthesis of (+)-Tanikolide Kita, Y.; Matsuda, S.; Fujii, E.; Horai, M.; Hata, K.; Fujioka, H. Angew. Chem. Int. Ed. 2005,44, 5857-5860.

  34. Applications in Total Synthesis • Synthesis of (+)-Tanikolide Kita, Y.; Matsuda, S.; Fujii, E.; Horai, M.; Hata, K.; Fujioka, H. Angew. Chem. Int. Ed. 2005,44, 5857-5860.

  35. Carbon-Carbon Bond Forming Reactions

  36. Carbon-Carbon Bond Forming Reactions: Cyclizations with PhI(OCOR)2 • PhI(OCOR)2 reagents have been shown to promote attack by carbon nucleophiles: Kita, Y.; Takada, T.; Ibaraki, M.; Gyoten, M.; Mihara, S.; Fujita, S.; Tohma, H. J. Org. Chem. 1996,61, 223-227.

  37. C-C Bond Forming Cyclizations Kita, Y.; Takada, T.; Ibaraki, M.; Gyoten, M.; Mihara, S.; Fujita, S.; Tohma, H. J. Org. Chem. 1996,61, 223-227.

  38. Applications in Total Synthesis • Synthesis of (±)-Stepharine Honda, T.; Shigehisa, H. Org. Lett. 2006,8, 657-659.

  39. C-C Bond Forming Reactions: C-H Activation Kalyani, D.; Deprez, N.; Desai, L. V.; Sanford, M.S. J. Am. Chem. Soc. 2005,127, 7330-7331. Deprez, N.; Kalyani, D.; Krause, A.; Sanford, M. S. J. Am. Chem. Soc. 2006,128, 4972-4973.

  40. C-C Bond Forming Reactions: C-H Activation Kalyani, D.; Deprez, N.; Desai, L. V.; Sanford, M.S. J. Am. Chem. Soc. 2005,127, 7330-7331. Deprez, N.; Kalyani, D.; Krause, A.; Sanford, M. S. J. Am. Chem. Soc. 2006,128, 4972-4973.

  41. Mechanism of C-H Activation Dick, A. R.; Hull, K. L.; Sanford, M. S. J. Am. Chem. Soc. 2004,126, 2300-2301. Kalyani, D.; Deprez, N.; Desai, L. V.; Sanford, M.S. J. Am. Chem. Soc. 2005,127, 7330-7331.

  42. Outline • Background • Iodine(III) reagents • Iodine(V) reagents • Conclusions

  43. Preparation of IV Reagents • Caution: There have been reports of violent explosions occurring upon heating of these reagents to >200 °C Boeckman, Jr., R.K.; Shao, P.; Mullins, J.J. Org. Synth. 2000, 77, 141-152. Frigerio, M.; Santagostino, M.; Sputore, S. J. Org. Chem. 1999, 64, 4537-4538.

  44. Oxidations of Alcohols: A Brief Overview • DMP and IBX have been widely used for the mild oxidation of alcohols to ketones and aldehydes: Zoller, T.; Breuilles, P.; Uguen, D. Tetrahedron Lett. 1999,40, 6253-6256. Myers, A. G.; Zhong, B.; Movassaghi, M.; Kung, D. W.; Kwon, S. Tetrahedron Lett. 2000,41, 1359-1362. Smith, A.B., III; Kanoh, N.; Ishiyama, H.; Minakawa, N.; Rainier, J.D.; Hartz, R.A.; Cho, Y.S.; Moser, W.H. J. Am. Chem. Soc.2003, 125, 8228-8237.

  45. Dehydrogenation of Saturated Aldehydes and Ketones with IBX Nicolaou, K. C.; Zhong, Y.-L.; Baran, P. S. J. Am. Chem. Soc. 2000,122, 7596-7597.

  46. Dehydrogenation of Saturated Aldehydes and Ketones with IBX Nicolaou, K. C.; Zhong, Y.-L.; Baran, P. S. J. Am. Chem. Soc. 2000,122, 7596-7597.

  47. Mechanism of Dehydrogenation by IBX • Single electron transfer is likely operative: Nicolaou, K. C.; Montagnon, T.; Baran, P. S.; Zhong, Y.-L. J. Am. Chem. Soc. 2002,124, 2245-2258.

  48. Applications in Total Synthesis • Efforts toward the synthesis of Phomoidride B Ohmori, N. J. Chem. Soc., Perkin Trans. 1 2002, 755-767.

  49. Tandem Conjugate Addition/Dehydrogenation with IBX Nicolaou, K. C.; Gray, D. L. F.; Montagnon, T.; Harrison, S. T. Angew. Chem. Int. Ed. 2002,41, 996-1000.

  50. Tandem Conjugate Addition/Dehydrogenation with IBX Nicolaou, K. C.; Gray, D. L. F.; Montagnon, T.; Harrison, S. T. Angew. Chem. Int. Ed. 2002,41, 996-1000.

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