Molecular sieves, chiral metal complex

Molecular sieves, chiral metal complex catalysis, 395... 

The discovery, in the mid-eighties, of the remarkable activity of TS-1 as a catalyst for selective oxidations with aqueous H2O2 fostered the expectation that this is merely the progenitor of a whole family of redox molecular sieve catalysts with unique activities. However, the initial euphoria has slowly been tempered by the realization that framework substitution/attachment of redox metal ions in molecular sieves does not, in many cases, lead to a stable heterogeneous catalyst. Nevertheless, we expect that the considerable research effort in this area, and the related zeolite-encapsulated complexes, will lead to the development of synthetically usefril systems. In this context the development of chiral ship-in-a-bottle type catalysts for intrazeolitic asymmetric oxidation is an important goal. Such an achievement would certainly justify the appellation mineral enzyme . 

Katsuki-Sharpless asymmetric epoxidation. Since its introduction in 1980 [10], the Katsuki-Sharpless asymmetric epoxidation (AE) reaction of allylic alcohols has been one of the most popular methods in asymmetric synthesis ([11-14]). In this work, the metal-catalyzed epoxidation of allylic alcohols described in the previous section was rendered asymmetric by switching from vanadium catalysts to titanium ones and by the addition of various tartrate esters as chiral ligands. Although subject to some technical improvements (most notably the addition of molecular sieves, which allowed the use of catalytic amounts of the titanium-tartrate complex), this recipe has persisted to this writing. 

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