Alcohols asymmetric epoxidation

Chiral endoperoxides, synthesis, 260, 261 Chiral hydroperoxides aUyhc alcohol asymmetric epoxidation, 401-6, 407-9... 

Sharpless asymmetric epoxidation of allylic alcohols, asymmetric epoxidation of conjugated ketones, asymmetric sulfoxidations catalyzed, or mediated, by chiral titanium complexes, and allylic oxidations are the main classes of oxidation where asymmetric amplification effects have been discovered. The various references are listed in Table 4 with the maximum amplification index observed. 

Unlike the Sharpless epoxidation, which gives ehiral epoxides fix)m allylic alcohols, asymmetric epoxidation of unfimctionalized alkenes achieved by Jacobsen et al. [74],by using chiral salen-metal catalysts. Salen-Mn catalysts are preferred since manganese itself is relatively a low eost and nontoxic metal, primarily because of fewer side reaetions over other metal eomplexes. Variety of simple oxidants, such as PhlO, NaClO, and oxone are employed as reoxidants and best possible enantioselectivity for a given substrate could be achieved by choosing the proper metal-salen catalyst and reaction conditions [81], The catalyst can be Irne-tuned for required steric and electronic properties by making a variety of chiral salen ligands fi om various chiral diamines with salicylaldehyde derivates [82]. 

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