Interchange of functional groups

Apply stereoselective transforms to clear stereocenters by removal or interchange of functional groups with the establishment of the retron for a disconnective transform, especially with retrosynthetic generation of the core groups C=C, C=0 or C=N. 

General.—Much of organic chemistry is about the introduction and interchange of functional groups the following instances are given here to illustrate recent advances... 

Easier to come by and just as useful is information about conversion of the functional groups. Each link-up in reactions 10.4 and 10.5 eliminates the two functional end groups that react with one another, and any interchange by reaction 10.7 leaves their number unchanged. Accordingly, the disappearance of functional groups is a bimolecular reaction and so essentially follows second-order kinetics. If the reverse reaction and polymer split-up are insignificant or suppressed, e.g., by removal or elimination of the cast-off small molecule Q as it is formed, the rate is... 

Equal reactivity of functional groups has been demonstrated by measurements of reaction rates of several series of reactants which differ in molecular weight. Further evidence is provided by the occurrence of interchange reactions under... 

Titanium chelates are formed from tetraalkyl titanates or haUdes and bi- or polydentate ligands. One of the functional groups is usually alcohoHc or enoHc hydroxyl, which interchanges with an alkoxy group, RO, on titanium to Hberate ROH. If the second function is hydroxyl or carboxyl, it may react similarly. Diols and polyols, a-hydroxycarboxyflc acids and oxaUc acid are all examples of this type. P-Keto esters, P-diketones, and alkanolamines are also excellent chelating ligands for titanium. 

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