Deprotonation‐Hydride Elimination as a Method of Dehydrogenation

Abstract

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 Convergence was achieved by means of an SCF damping routine (D. Poppinger, unpublished).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.

Synthesis ofcis‐ andtrans‐Configured Octahydroperylenes

“…A pK a value of about 30-35 was estimated for these compounds (for diphenylmethane a pK a of 33.5 has been given [14] ), which should allow for a deprotonation with alcoholates. We also tested a method proposed by Reetz, [15] aiming for anthracene derivative 7 (vide infra), in which fenchone is used as a hydride acceptor together with butyllithium and N,N′-tetramethylethylenediamine (TMEDA). Nevertheless, not even a trace of deuterium incorporation was observed in the 1 H NMR spectra when trans-6 was treated with a solution of potassium tert-butoxide in deuterated methanol for 2 d (Table 1, Entry 1).…”

“…Nevertheless, not even a trace of deuterium incorporation was observed in the 1 H NMR spectra when trans-6 was treated with a solution of potassium tert-butoxide in deuterated methanol for 2 d ( Table 1, Entry 1). We also tested a method proposed by Reetz, [15] aiming for anthracene derivative 7 (vide infra), in which fenchone is used as a hydride acceptor together with butyllithium and N,N′-tetramethylethylenediamine (TMEDA). It turned out that in our hands, this combination was suitable for a deprotonation/protonation of octahydroperylene trans-6 ( Table 1, Entries 2-5).…”

The Dibenzosuberenone Scaffold as a Privileged Substructure: From Synthesis to Application

“…59 Reetz and Eibach developed a method for the dehydrogenation of dihy-droarenes, based on deprotonation-hydride elimination, in which potassium fencholate (45) serves as the base and fenchone (46) as the hydride acceptor. 60 Since potassium fencholate (45) is regenerated in the aromatization step, only a catalytic amount is required. In this way, the conversion of dibenzosuberone (6) into 5-dibenzosuberenone (1) proceeded in 90% yield.…”