Sharpless Asymmetric Dihydroxylation Reaction

Sharpless Asymmetric Dihydroxylation Reaction - Myers...

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Chem 2 15 Sharpless Asymmetric Dihydroxylation Reaction Os O O O O Os O L O O O Os O L O O O VIII VI 2 H 2 O, 2 OH H 4 OsO 6 2- O N O CH 3 K 3 Fe(CN) 6 VI HO HO Review : Kolb, H. C.; VanNieuwenhze, M. S.; Sharpless, K. B. Chem. Rev. 1994 , 9 4 , 2483-2547. Ligands such as pyridine accelerate the osmylation of olefins (Criegee, R.; Marchand, B.; Wannowius, H. Liebigs Ann. Chem. 1942 , 550 , 99-133.) + + L L 2 Fe(CN) 6 3– 2 Fe(CN) 6 4– Catalytic Cycle : Turnover is achieved by re-oxidation with stoichiometric oxidants : + UpJohn Process: VanRheenen, V.; Kelly, R. C.; Cha, D. Y. Tetrahedron Lett. 1976 , 1973-1976. Minato, M.; Yamamoto, K.; Tsuji, J. J. Org. Chem. 1990 , 5 5 , 766-768. In the original Sharpless procedure, using NMO, reoxidation was believed to compete with hydrolysis, leading to a competing 2nd-cycle oxidation that was less enantioselective: Ogino, Y.; Chen, H.; Kwong, H.-L.; Sharpless, K. B. Tetrahedron Lett. 1991 , 3 2 , 3965-3968. Balance of evidence appears to favor 3 + 2 Mechanism (vs. 2 + 2 pathway) . See, e.g., Corey, E.J.; Noe, M. C.; Grogan, M. J. Tetrahedron Lett. 1996 , 3 7 , 4899-4902. DelMonte, A. J.; Haller, J.; Houk, K. N.; Sharpless, K. B.; Singleton, D. A.; Strassner, T.; Thomas, A. A. J. Am. Chem. Soc. 1997 , 119 , 9907-9908.
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