New Phase Tags and Sorting Tags for Organic Synthesis

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DESCRIPTION (provided by applicant): Chemical separation methods should be efficient, scalable, predictable, and readily automated to increase the diversity of available drug candidates, reduce the amounts of waste solvent produced in chemical production, reduce human exposure to chemical agents, and reduce the time and cost of chemical discovery. Phase tags are molecular fragments, or aggregates, that control the solubility or chromatographic behavior of tagged molecules. Phase tags are frequently used in the synthesis of combinatorial libraries of drug candidates. The greater objective of this project at the University of Pittsburgh is to develop new types of phase tags and new methods for separating tagged molecules from complex mixtures. This project will investigate two new categories of phase tags. The first category - protean phase tags - includes molecules that can, on activation, change shape to switch between an "organic soluble state" and an "organic insoluble state". On activation of a mixture containing tagged and untagged molecules, only the tagged molecules precipitate. We call such tags "precipitons" - and these were the first example of protean phase tags. This project will study two types of protean phase tags: (1) recyclable precipitons based on stilbenes for controlling organic solubility, and (2) new protean phase tags for controlling water solubility. The second new category of phase tags - sorting tags* - is based on simple oligomers, here designated (X)N. Our objective is to demonstrate that a mixture of N tagged molecules, RN-O-(X)N, (where RNrepresent the molecules and (X)N represent the N phase tags) can be subjected to simultaneous reactions in one vessel and that after the reaction is complete the N molecules may be isolated as a mixture for a subsequent reaction, or easily separated to provide the N pure products. Sorting tags and the target technology will complement and extend fluorous mixture synthesis, a method pioneered by Curran in this department. The methods will be tested by molecular library syntheses and development of precipiton-bound reagents, new scavengers for solution phase synthesis, and can be extended to create new ligands for catalyst recovery or metal scavenging. *[Sort: 1. To arrange according to class. 2. To separate from others.]