Synthesis of 9,10–Dihydro–9,10–propanoanthracen–12–ones Substituted at the Bridgehead

A variety of 9,10–dihydro–9,10–propanoanthracen–12–ones 1–11 has been prepared from anthracenes 15–23 , α,α′‐dibromo ketones 12–14 and zinc/copper couple by using dioxane as solvent and ultrasonication at 15–20°C. 2,2,4,4–Tetrabromoacetone ( 12 ) afforded cycloadducts, in which the two bromine atoms at C–11 and C–13 are introduced stereoselectively cis and adopt a syn diaxial instead of a cis ‐diequatorial position (5 examples). Even the cis ‐configurated methyl groups in adducts 8, 9 and cis ‐ 11 adopt syn diaxial positions preferentially.