Application of asymmetric Sharpless aminohydroxylation in total synthesis of natural products and some synthetic complex bio-active molecules

Abstract

This work shows applications of Asymmetric Sharpless Aminohydroxylation (ASAH) in the stereoselective synthesis of vicinal amino alcohols as important intermediates in the total synthesis of complex molecules and natural products with significant biological activities.

Applications of Wittig Reaction in the Total Synthesis of Natural Macrolides

“…On the other hand as we mentioned macrolides are significant natural products from structural and biological points of view. Thus, due to our interest in Wittig reaction [37,38] and in the applications of other name reactions in the total synthesis of natural products, [39][40][41][42][43][44][45][46][47] herein, we try to underscore the applications of the Wittig reaction in the total synthesis of natural products, classified as macrolide family, especially those showing biological potencies.…”

Kinetic detection of osmium(VI) ester intermediates during the OsO4‐mediated aqueous dihydroxylation of chloroethylenes

“…Therefore, it is often imperative to use osmium as a catalyst in the process, which can be readily achieved by adding a less expensive stoichiometric oxidizing agent that is able to transform the product osmium(VI) back into osmium tetroxide. Hydrogen peroxide, tert ‐butyl‐hydroperoxide, N ‐methylmorpholine N ‐oxide, dioxygen, chlorate ion, hypochlorite ion, and periodate ion have all been reported to be suitable for this purpose under certain conditions . Despite the vastly different properties of these oxidants, it is a common aspect that they do not react with the substrate olefin directly, and their only role is to reproduce the initial form of the catalysts .…”

“…However, these molecules might very well represent unreactive dead ends as far as the dihydroxylation process is concerned. The process can be carried out in an enantioselective way by adding coordinating chiral amines as coligands . These are understood to exert an influence on the process by coordinating to the osmium center directly.…”

“…Hydrogen peroxide, tert-butylhydroperoxide, N-methylmorpholine N-oxide, dioxygen, chlorate ion, hypochlorite ion, and periodate ion have all been reported to be suitable for this purpose under certain conditions. [1,2,[7][8][9][10][11][12][13] Despite the vastly different properties of these oxidants, it is a common aspect that they do not react with the substrate olefin directly, and their only role is to reproduce the initial form of the catalysts. [1,2] Therefore, it is clear that the kinetics and the efficiency of a catalytic method are dominantly determined by the interaction of the oxidizable substrate with osmium tetroxide, and kinetic studies on this process in the absence of an extra oxidizing agent may provide insightful information on the mechanism and the potential application of the method.…”

“…The process can be carried out in an enantioselective way by adding coordinating chiral amines as coligands. [2,8,9,11,13] These are understood to exert an influence on the process by coordinating to the osmium center directly.…”