Synthesis of 9,10‐Dihydro‐9,10‐propanoanthracene‐12‐ones from Anthracenes and Oxyallyl Cation Intermediates Generated by the the BSA [ N,O ‐Bis(trimethylsilyl)acetamide] Method

Sonication of a zinc/copper couple, N,O ‐bis(trimethylsilyl)‐acetamide (BSA) and α,α'‐oligobromo ketones in benzene gives rise to oxyallyl intermediates which cycloadd to anthracene. Starting from 1,1,3,3‐tetrabromoacetone ( 2a ) and anthracene ( 1a ), we obtained 11,11,13‐tribrominated adduct 4 as the major product (42%). The expected 11,13‐dibrominated adduct trans ‐ 3 was formed as a minor product (5%), but it became the main product when the known oxyallyl methodology was applied. Dibenzohomobarrelenes 9 and 17 were prepared by short routes.