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Introduction of Combinatorial Chemistry 5th Year Pharmacy 2016-2017 Definition A branch of applied chemistry concerned • with the rapid synthesis and screening of large numbers of different but related chemical compounds generated from a mixture of known building blocks in order to recover new substances optimally suited for a specific function Other definition that make it possible to prepare a large • number (tens to thousands or even millions) of compounds in a single process. These compound libraries (products ) can be made as mixtures, sets of individual compounds or chemical structures generated in silico Disadvantages High affected molecular size, solubility, • Achiral products • 1- Solid Phase Synthesis A common combinatorial technique uses • organic synthesis on solid support. Linker groups are attached to resin beads in the solid phase and the reactants are passed over in solution to make the intermediates and a final detachment-from-resin reaction is run to get the desired product out of the column. SUPPORTS AND LINKERS Most solid-state combinatorial chemistry is • conducted by using polymer beads 10 to 750 µm in diameter. The polymers are inert, except for the • functional groups to which the molecules are attached. In general, the compounds 10 be synthesized are not attached directly to the polymer molecules. They are usually attached using a "linker"" • moiety that : • a) enables attachment in a way that can be • easily reversed without destroying the molecule that is being synthesized and b ) allows some room for rotational freedom • of the molecules attached to the polymer The types of solid supports that are used include Poly styrene resins, • TentaGel resins • Polyacyamide resins • Glass & Ceramic resins • Mixed Combinatorial Synthesis There 20 amino acids • AA1 + AA2 AA1-AA2 ( 20 )n n=2 20 X 20 = 400 DIPEPTIDES AA1 + AA2 + AA3 AA1-AA2-AA3 ( 20 )3 20 X 20 X20 = 8000 TRIPEPTIDES Home work calculate mixed combinatorial synthesis of Tetrapeptides ? DETECTION, PURIFICATION, AND ANALYSIS Detection, analysis, and purification of combinatorial • libraries places high demands on exiciting analytical techniques • because {a) the quantities to be analyzed are very small, • sometimes pico-moles of materials (b) the analysis should • be non destructive, to allow recovery of the compound if • possible, and c) the methods must be suitable for rapid • parallel analysis • Chromatographic methods used ( HPLC – MS). • FT-IR ( Fourier transmission Infra-red )spectroscopy • NMR ( Nuclear Magnetic Resonance ) Spectroscopy •