Crowded Anthracenes. I. 1,4,5,8-Tetraphenyl- and 1,4-Diphenyl-9,10-dihydroantracene

Crowded Anthracenes. I. 1,4,5,8-Tetraphenyl- and 1,4-Diphenyl-9,10-dihydroantracene

“…Molecular orbital calculations indicate that quinodimethanes, which lack substituents on the methylene groups, possess unusually high free valence at the terminal carbon atoms. 1 In agreement with these predictions compounds such as /7-xylylene2 and 9,10- (2) The chemistry of p-xylylene and its polymers has been reviewed by L. A. Errede and M. Szwarc, Quart. Rev.…”

“…We are actively investigating the synthesis of other potentially stable quinodimethanes and the chemistry of 1 and 2.16 We wish to report the synthesis of the crowded molecules 1,4,5,8-tetraphenyl-9,10-dimethylanthracene (1) and 1,4,5,8-tetraphenyl-10-methyl-9-methylene-9,10-di-hydroanthracene (2) from 1,4,5,8-tetraphenyl-9,10-dimethylene-9,10-dihydroanthracene.1 The results of equilibration studies are given, and applications to quantitative aspects of long-range magnetic shielding are discussed.…”

“…Catalytic hydrogenation of l,4,5,8-tetraphenyl-9,10dimethylene-9,10-dihydroanthracene1 gave a mixture composed of about 34% 1 and 66% 2. The combined solids were extracted and then recrystallized under nitrogen to yield the less soluble component, 1 (singlet, six methyl protons), 7.0-7.6 (multiplet, 24 aromatic protons). Column chromatography of the hydrogenation mixture furnished 2, C40H30, mp 212.5-214°, m/e 510, X^f% µ (log e) 250 (4.76), nmr (CDC13, internal TMS)…”

Stereoisomeric p-Quinodimethanes

“…The only solution-phase experimental evidence for the boat geometry in hydrocarbon systems is a single dipole moment measurement …”

“…A small number of isolable 9,10-anthraquinodimethanes − have been described briefly in the literature. Our own first effort in this area included the first X-ray crystal structure of an isolable all-carbon quinodimethane, namely 1 . , There have been no reports of stereoisomerism in isolable quinodimethanes though compounds capable of stereoisomerism (geometric isomers) such as E,E-1,4-dimethyl-9,10-(bis)ethylidene-9,10-dihydroanthracene (( E , E ) -2 ), among the simplest of anthraquinodimethanes capable of having geometric isomers, have been reported .…”