Functionalization arene-catalyzed lithiation

Oxido functionalized organolithium compounds of type 128 or 131 are also accessible by sulfur-lithium exchange using the arene-catalyzed lithiation technology. 

In this section, functionalized aryl and heteroaryl compounds prepared by arene-catalyzed lithiation will be considered. 

The preparation of functionalized aryllithium compounds bearing an oxygen- or sulfur-containing functionality in a benzylic position is also possible by arene-catalyzed lithiation. When chlorinated materials 239 were deprotonated (for Y = OH, SH) with n-butyllithium in THF at —78 °C and then lithiated using DTBB as the catalyst at the same temperature. 

Cyclic alkyl aryl ethers lead also to functionalized organolithium compounds by reductive carbon-oxygen bond cleavage in arene-catalyzed lithiation process. Thus, the treatment of 2,3-dihydrobenzofuran (47) with an excess of lithium in the presence of a catalytic amount of DTBB in THF at 0°C gives the dianion (48) which after reaction with different carbonyl compounds and final hydrolysis with water leads to... 

On the basis of the catalytic roles of calix[4]arene derived model 18-[Zn"]2 (99JOC3896) and cis-diaqua Cu complexes for cleavage of phosphate diesters, Reinhoudt designed a calix[4]arene derivative 66-[Cu ]2 functionalized with two ds-diaqua Cu° centers at the distal positions of the upper rim as a model for dinuclear metalloenzymes that catalyze chemical transformations of phosphate esters. It was synthesized from Cu(C104)2 and 5,17-bis(bis(l-methylimidazol-2-yl)hydroxy-methyl)-25,26,27,28-tetrakis(2-ethoxyethoxy)calix[4]arene which was conveniently obtained from the precursor diester and lithiated 1-methyl-imidazole. In this model, the two Cu° centers are well organized on the calixarene scaffold for performing S5mergistic action. 

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