Abstract: Organic reactions encounter difficulties with selectivities, especially when multiple reactive sites are present within the molecules. A newly emerging concept to address selectivities in a reaction is built up through determining the relative reactivities of the varied reactive sites of the substrate by experimental methods. This method provides a parameter to quantify the reactivity of varied reactive sites and enable prediction of reactivity and selectivity. In this presentation, I will discuss this concept and its application in the field of complex oligosaccharide synthesis. Previous work done in the area of glycosylation reactions involves the manipulation of the protecting groups to vary the reactivity of the glycosyl donor. This enabled a chemoselectivity in the reaction. The Wong group1-3 attempted to express the reactivity of a series of reactive substrates, with different protecting groups, yet present with a particular activation moiety, and characterized the reactions in terms of a parameter called Relative Reactivity Value (RRV). In this presentation, I will cover the method used to determine RRV values and observations made on the structural factors which affect the reactivities. Softwares, namely, OptiMer and Auto-CHO, were developed, using these RRV values. Such software enables the selection of building blocks (BBL’s), so as to achieve the best yield for multi-step target molecule synthesis in one pot. This emerging concept opens up possibilities for predictions of other reactions as well – by creating a database of substrates along with their reactivity parameter. Using this emerging tool, which combines experimental observations with machine learning predictions, it should be possible to devise optimal routes for multistep organic synthesis of complex target structures.
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