Summary Epoxide Syntheses

Summary Epoxide Syntheses 648 14-12 Acid-Catalyzed Ring Opening of Epoxides 649... 

In summary, epoxides are produced not only as endproducts, but also as intermediates because they are valuable building blocks in synthetic organic chemistry [82-84] (Table 1.3). Until recently, epoxide intermediates were produced by direct oxygen transfer to olefins by a variety of stoichiometric methods. Recently, considerable efforts have been made to conduct the transformations selectively under catalytic conditions. Because epoxides are reactive substances, they can undergo diverse transformations by reactions with acids and bases, and their reactivity has been exploited to form a diverse range of products by so-called click chemistry [85,86], which combines the breadth of combinatorial methods with the precise synthesis of organic chemistry. 

Table 8, Summary of Synthesis of Linear Polyoxazolidones (Different Epoxides with MDI)... 

In summary, the organically functionalized Ti-substituted MCM-41 materials have been successfully synthesized by one-step synthesis method with a varied Ti-incorporation of the Si/Ti ratio from 50 to 600. The hydrothermal treatment resulted in the increase of Ti-incorporation. The epoxidation selectivity was improved by organic functionalization than alcohol oxidation probably due to the increased hydrophobicity nearby the Ti-active sites. 

Summary Reactions of Ethers 641 14-10 Thioethers (Sulfides) and Silyl Ethers 642 14-11 Synthesis of Epoxides 646... 

Asymmetric Induction at the Allylic Alcohol Centre AE is anti-Selective No Asymmetric Induction from Remote Allylic Alcohol Centre Reagent Control Asymmetric Synthesis of Diltiazem Summary of Sharpless Epoxidation... 

In summary, the goal of this combinatorial approach - the discovery of catalysts for the asymmetric epoxidation of olefins using dihydrogen peroxide as the terminal oxidant - was met The Fe-complexes of the ligands 12a-14f, 12a-14g, and 13c-14b indeed afforded up to 20% ee, at epoxide yields of up to 78 %. In this study proof-of-principle was clearly achieved. For practical applications in asymmetric synthesis, further improvement of the catalyst enantioselectivity appears desirable and represents the next challenge to be met. 

In summary, the broad application of the Shi epoxidation in the total synthesis of natural products and in drug discovery is a good indication that the reaction will receive more attention and find extended use in the future. Together with the Sharpless epoxidation and the Jacobsen epoxidation, Shi epoxidation has been considered one of the three major catalytic enantioselective epoxidations useful for the synthesis of ehiral epoxides. 

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