The Elbs reaction enables the synthesis of condensed aromatic systems. As already demonstrated by Elbs in 1884 it is possible to obtain anthracene through dehydration. Larger aromatic systems like pentacene are also feasible. This reaction does not take place in a single step but leads first to dihydropentacene that is dehydrogenated in a second step with copper as a catalyst.
The acyl compounds required for this reaction can be obtained through a Friedel-Crafts acylation with aluminum chloride.
The Elbs reaction is sometimes accompanied by elimination of substituents and can be unsuited for substituted polyaromatics.