Tetracyclic bishomobenzoctamine as a homologue of benzoctamine 1 was synthesised. The key intermediate 9-(prop-2-en-1-yl)-9,10-dihydro-9,10-propanoanthracen-12-one was successfully synthesised via [3+4] cycloaddition of tetrabromoacetone on 9-allylanthracene by using ultrasonication at 15–20 °C followed by debromination.
