9.10- Dihydroanthracene, synthesis

Applied to the synthesis of hydrocarbons the following results have been obtained by this new method. 9 10-Diphenyl-9 10-dihydroanthracene is formed by the condensation of benzene and chloroform, whilst in the ordinary Friedel-Crafts reaction (A., 194, 254 227, 107) triphenyl-methane (Preparation 6) is the main product, traces of chlorarylmethanes and tetraphenylethane (B., 26, 1952) being also formed. The same compound is also obtained from benzal chloride and benzene. Carbon tetrachloride and benzene give 9 9 10 10-tetraphenyl-9 10-dihydroanthracene as do also phenylchloroform and benzene. In the older reaction triphenylchloromethane (p. 432) is the chief product. 

Cyclotriveratrylene was first prepared by Gertrude Robinson in 1915 (Scheme 7.2). Robinson was interested in following up earlier work on the synthesis of anthracene derivatives and concluded that her product (empirical formula, C7H10O2, was 2,3,6,7-tetramethoxy-9,10-dihydroanthracene (7.43), the dimer of the intermediate veratryl cation (7.42). During the 1950s, CTV was again reformulated erroneously as a hexamer (7.44) and it was not until 1963 that the onset of a variety of modern techniques established a trimeric formula. 

A synthesis of electrochemically amphoteric TTFAQ-ct-A derivatives 917 and 918 (TTFAQ = 9,10-bis(l,3-dithiol-2-ylidene)-9,10-dihydroanthracene, ct = saturated spacer, A = polynitrofluorene acceptor) involved esterification of the acid chloride 916 with the hydroxymethyl-substituted TTFAQ derivative 915 in pyridine. To increase acceptor properties, 917 was converted into the dicyanomethylene derivative 918 by reaction with malononitrile in DMF (Scheme 138) <2002JA14227>. 

The synthesis of 9,10-bis(l,3-dithiol-2-ylidene)-9,10-dihydroanthracene derivatives bearing two alkoxy chains attached to the anthracene spacer was also reported <2000EJ01199>. 

Wolthuis employed chloranil in refluxing xylene to effect nearly quantitative dehydrogenation of 1,4-dihydroanthracene derivatives such as (11) obtained by a synthesis starting with (9), the adduct of benzyne with furane. Functioning as an... 

Several extensions of this approach have been attempted, but none was successful. Only a faint odor results from the attempted synthesis of cyclopropa[Z)]naphthalene and none of the expected cyclopropa[a]naphthalene or cyclopropa[/]phenanthrene were generated in the corresponding reactions.- The same difficulties have been experienced with other benzyl derivatives. The reaction of 2-bromobenzyl bromide, 2-bromobenzyl chloride and 2-iodobenzyl bromide with butyllithium gave (partially) reduced bibenzyls or 9,10-dihydroanthracene, but no benzocyclopropene. Similarly, lithiation of 2-bromobcnzylsulfonates afforded only trace amounts (< 5%) of bcnzocyclopropene, while only methoxymethylbenzene was isolated on treatment of l-methoxymethyl-2-trimethylsiIylbenzene with fluoride ions. ... 

After last year s preliminary report on the synthesis of pentatetraene by a retro-Diels-Alder reaction involving flash thermolysis of (131), Ripoll has now published the full details and has also shown that the similar decomposition of ll-vinylidene-9,10-ethano-9,10-dihydroanthracene (132) at 750°C-10mm-Hg pressure gives an 85% yield of butatriene (133). To complement these developments, a timely publication has appeared on the theoretical basis and the instrumentation necessary for flash thermolyses, suitable for such experiments on a preparative scale. 

That the two carbon atoms joining the benzene rings are in the ortho-position followed from the synthesis by C. L. Jackson and J. F. White by heating o-bromobenzyl bromide with sodium and oxidising the resulting dihydroanthracene ... 

Anthracene and Related Compounds. The formation of anthracene by elimination of hydride from 9,10-dihydroanthracene has been reported in the preceding section. An improved high-yield synthesis of 7,12-dimethylbenz-[ajanthracene (336), a compound of biological interest, utilizes the reaction of 7,12-benz[a]anthraquinone with MeLi. Subsequent reaction with dry HCl in ethyl acetate produces 7-(chloromethyl)-12-methylbenz[a]anthracene, reduction of which gives (336). 

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