Thiophen Analogues of Anthracene

In order to study the keto-enol tautomerism of thiophen analogues of anthrone, three of the monothieno-analogues (412)—(414) and five of the 

Dewar para localization energies for some anthracene analogues have been computed. Another route to heterocyclic analogues of triptycene (433) is through the reaction of (432) with phosphorus pentasulphide. The starting material (432) was prepared by the Diels-Alder reaction of anthracenes with dibenzoyl- or diacetyl-ethylenes.  

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Thiophen Analogues of Anthracene and Phenantbrene.— The remaining member (237) of the thieno-analogues of anthrone-anthrol has been synthesized from the known (238) by reduction of one of the carbonyl groups to the ketal, followed by... 

Thiophen Analogues of Anthracene and Phenanthrene.— The six possible isomers (317)—(322) resulting from the replacement of one or both benzene... 

Thiophen Analogues of Polycyclic Aromatic Hydrocarbons Analogues of Anthracene and Phenanthrene. - Keto-enol tautomerism in a naphtho- and several anthra-thiophen systems [such as (241) (242)] has been studied. The system (241) (242) was obtained via the Friedel-Crafts reaction of thiophen with naphthalene-2,3-dicarboxylic anhydride followed by ring-closure. A [c] -fused system was similarly obtained by starting from... 

Analogues of Anthracene and Phenanthrene.—The tandem-directed metalla-tion reaction between thiophen-3-aldehyde and thiophen-3-carboxylic acid diethylamide has been found to be a very useful method for the synthesis of thiophen analogues of anthraquinones. A detailed procedure for the synthesis of benzo[l,2-6 4,5-f)]dithiophen has been published. The reaction of l-(2-naphthyl)-5,5-dimethyl-3-oxocyclohexene with sulphur gave (168). ... 

Valence isomer formation is a feature also of the photochemistry of naphthalenes (3.33) and anthracenes for naphthalenes, as for benzenes, the extent ol steric crowding helps to determine which type of valence isomer predominates, since there is more severe interaction in the bicyclohexadiene products than in the benzvalene products. Amongst five-membered heteroaromalic compounds there are many known ring photoisomerizations that involve conversion of a 2-substituled to a 3-substituted system (e.g. 3.34). In some cases non-aromatic products can be isolated, such as bicyclo[2.1.0]pentene analogues from thiophenes 13.35). or acylcycfopropenes from furans (3.36) related species may be... 

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