A single precision Telefunken TR 440 version of this program, written by H.-U. Wagner, was employed. Convergence was achieved by means of an SCF damping routine (D. Poppinger, unpublished). The ' T -N M R chemical shifts of the lithium-bearing carbons are (THF solution, &values): vinyllithium, 183.4; phenyllithium, 186.4 [J. P. C.
Ein auf Deprotonierung-Hydrideliminierung basierendes Prinzip der Aromatisierung wurde experimentell gepruft, indem Dihydroaromaten mit verschiedenen Base-Hydridacceptor-Paaren umgesetzt wurden. Dabei erwies sich Kaliumfencholat-Fenchon als besonders wirksam. So lassen sich nicht nur einfache Dihydroaromaten aromatisieren, sondern auch Vertreter, die zu reaktiven, mit konventionellen Dehydrierungsagenzien praparativ nicht darstellbare Aromaten fuhren. Kontrollversuche in Abwesenheit von Hydridacceptoren zeigen, da8 metallierte Dihydroaromaten selbst nur langsam Hydridionen abspalten.
Hydride Eliminations, VIII). -Deprotonation -Hydride Elimination as a Method of AromatizationA new aromatization technique based on deprotonation -hydride elimination has been experimentally tested by reacting dihydroarenes with various base -hydride acceptor pairs. It turned out that postassium fencholate -fenchone is particularly suitable:Thus, not only simple dihydroarenes can be aromatized, but also those which afford reactive arenes which cannot be prepared using conventional dehydrogenation agents. Control experiments in the absence of hydride acceptors show that metalated dihydroarenes themselves only undergo slow hydride eliminations.
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