Atyl alkylation

The triphenyls are probably polymeric and the first fully-characterized compound was [Li(thf)4][Lu(C6H3Me2)4] in which the Lu is tetrahedrally coordinated to four cr-atyl groups. More stable products, of the form [LnR3(thf)2], are obtained by the use of bulky alkyl groups such as -CH2CMe3 and -CH2SiMe3. 

Despite its utility, the Friedel-Crafts alkylation has several limitations. For one thing, only alkyl halides can be used. Aromatic (atyl) halides and vinylic halides do not react because aryl and vinylic carbocations are too high in energy to form under Friedel-Crafts conditions. 

Note that the Wolff-Kishner reduction accomplishes the same overall trans-fonnation as the catalytic hydrogenation of an acylbenzene to yield an alkyl-benzene (Section 16.10). The Wolff-Kishner reduction is more general and more useful than catalytic hydrogenation, however, because it works well with both alkyl and atyl ketones. 

The catalytic cycles for reduction of alkyl and atyl halides using Ni(o), Co(i) or Pd(o) species are interrupted by added carbon dioxide and reaction between the first formed carbon-metal bond and carbon dioxide yields an alkyl or aryl car-boxylate. These catalyses reactions have the advantage of occuriiig at lower cathode potentials than the direct processes summarised in Table 4.14. Mechanisms for the Ni(o) [240] and Pd(o) [241] catalysed processes have been established. Carbon dioxide inserts into the carbon-metal bond in an intermediate. Once the carboxy-late-metal species is formed, a further electron transfer step liberates the carboxy-late ion reforming the metallic complex catalyst. 

R R = H, alkyl, alkenyl, atyl R R = H, alkyl, aryl, Oalkyl... 

N-lithioethylenediamine, 567-570 Lithium, 18, 570-573 alkyl and atyl derivatives, 571-573 Lithium acetylide, 573-574 Lithium acetylide-Ethylenediamine, 574 Lithium alkanyls, 280 Lithium-Alkylamine reduction, 137, 138, 574-581... 

A series of 2-alkyl(aTyl)thio-3//-quinolin-4-ones 120 were synthesized in a thermally induced cyclization <05OL5281>. Initially, the ketenimine 121 undergoes a [1,5] sigmatropic migration of the alkyl(aryl)thio group to form 122 followed by a 67t-electrocyclic ring closure resulting in the formation of 120, illustrated in Scheme 34. 

Abbreviations Aik, alkyl AN, acetonitrile Ar, atyl Bu, butyl cod, 1,5-cyclooctadiene Cp, cy-clopentadienyl Cp, pentamethylcyclopentadienyl Cy, cyclohexyl dppm, diphenylphosphinome-thane dpme, Ph2PC2li(PMe2 Et, ethyl fod, 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octane-dionate HOMO, highest occupied molecular orbital LUMO, lowest unoccupied molecular oibital Me, methyl MO, molecular orbital nbd, noibomadiene Nuc, nucleophile OTf, triflate Ph, phenyl Pr, propyl py, pyridine THF, tetrahydrofliran TMEDA Al,AyV, lV -tetramethylethylenediamine. 

R = H (reductive coupling), R = alkyl or atyl (alkylaHve coupling)... 

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