Analogues of Anthracene and Phenanthrene

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). ... 

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

The nx)st imponam ring system of organic chemistry is (he benzene nng. either as a separate entity or in polynuclear hydrocarbons such as naphthalene, anthracene, and phenanthrene. Inorganic chemistry has two (at (east) analogues ofbenzene borazincs. and trimeric cyclophosphazene compounds. 

This is the first attempt to review all fused heterocyclic systems (6 6 6) containing at least one ring junction heteroatom. There are three classes of these systems, namely heterocyclic analogues of anthracene, phenanthrene, and phenalene, which are surveyed in Tables 1-3 respectively. Please... 

C-3 of the naphthalene nucleus that controls the electrophilic ring-closure of the vinyl ketene intermediate moreover, the degree of aromaticity of the angular rings in the phenanthrene skeleton exceeds that in the anthracene analogues. This regioselectivity observed in the benzannulation of chromium carbenes is paralleled by results observed for 2-naphthyl cyclo-butenones [77] and for the palladium-catalyzed cyclocarbonylation of 2-naphthyl allyl acetates [78]. 

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