Functional group replacement

TABLE 11.1 Activity of Galanin Subtype-3 Receptor Antagonists4 

SCHEME 11.2 Optimization by independently modifying sections of the lead 

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Substitution reactions occur when one functional group replaces another. Two important types of substitution reactions are SN1 and SN2. These are substitution, nucleophilic, unimoleeular and bimolecular. The numbers represent the order of the rate law and NOT the number of steps. 

A strategy based on functional group replacement was developed to dissect the contribution of individual hydroxyl groups to the free energy... 

This generalization of the Centrally Inverted Map Method (CIMM) of molecular shape complementarity analysis [2] to FIDCOs of functional groups replaces the problem of complementarity evaluation with a conceptually and computationally simpler similarity evaluation. 

Carbonyl-like reactivity is found with a number of other functional groups. Replacement of the oxygen of the carbonyl (C=0) group with nitrogen leads to imines(C=N-R) and to nitriles (CsN). These possess both an electron-deficient carbon and adjacent substituents which are activated by the imine (see 3.9) or nitrile (see 3.10). 

Step 4. If the molecule includes Group A functional groups, replace the last "e" with the suffix of the highest priority functional group, and include its position number just before the name of the highest priority functional group. 

Both reactions are classified as substitutions, a term that describes the relationship between reactants and products—one functional group replaces another. In this chapter we go beyond the relationship of reactants and products and consider the mechanism of each reaction. A mechanism attempts to show how starting materials are converted into products during a chemical reaction. 

Identify the major functional group. Replace -ane (in the alkane) with a suffix. 

Oryzalin (6) is an anal( e of trifluralin (4) where the trifluoromethyl group is replaced with a sulfonamide group. This functional group replacement aids aqueous solubility, making oryzalin (6) a more attractive lead compound. Oryzalin (6) has been shown to inhibit the assemb of 7.5 pM leishmanial tubulin assembly by approximately 54% at a concentration of 25 pM."... 

Substitution is an extremely common type of chemical reaction in which one element or functional group replaces another rarely, however, is the product referred to as substituted. In the reaction of hydrogen chloride with ethanol. 

In assessing potential isosteres, it is important that functional group replacements give rise to broadly similar conformations, and the CSD System and Mogul are rich... 

Reaction in which one atom or functional group replaces another Usually involves saturated or aromatic compounds ... 

Functional group replacement by cyano is an important synthetic transformation since it frequently allows homologation by hydrolysis to the carboxylic acid, or by reduction to an amine. The replacement of sulphinyl by cyano via trimethyl-silylcyanide thus provides a preparation of aliphatic cyanomethyl ethers, and this useful reagent has been further employed to provide cyclic a-acylaminonitriles by the replacement of methoxy-groups. The replacement of a primary amino-group by cyano is an often sought after transformation, and... 

The guanine and hypoxanthine analogues of F-ara-A, F-ara-G (lb) and F-ara-H (Ic), were synthesized by us as well as by others, by condensation of 3-0-acetyl-5-0-benzoyl-2-deoxy-2-fluoro-D-arabinofuranosyl bromide with N -benzoyladenine, 6-chloropurine, 2,6-dichloropurine, or 2-acetamido-6-chloropurine, followed by appropriate functional group replacement and deprotection. It was found that the guanine nucleoside lb is selectively toxic to T-cells while the hypoxanthine congener Ic is a potent inhibitor of the growth of Leishmania tropica promastigotes . 

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