Dibenzothiophene → Anthra[2,3-b]benzo[d]thiophene-7,12-dione

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Reaction Steps

The synthesis of the anthra[2,3-b]benzo[d]thiophene unit with added trialkylsilylethynyl groups is shown in Scheme 1. Commercially available dibenzothiophene undertakes a Friedel-Crafts reaction with phthalic anhydride to give 2-(2′-carboxybenzoyl)dibenzothiaphene. The acid is then treated with aluminum chloride and phosphorus pentachloride to yield anthra[2,3-b]benzo[d]thiophene-7,12-dione. The dione is alkylated with the lithium salt of the trialkylsilylacetylene reagent followed by aromatisation utilising tin (II) chloride under acidic conditions to give 7,12-bis(trialkylsilylethynyl)anthra[2,3-b]benzo[d]thiophene.

Provenance & Evidence