SYNTHESIS OF 9,10-DIHYDRO-9,10-PROPANOANTHRACENE-12-ONES FROM ANTHRACENES AND OXYALLYL CATION INTERMEDIATES GENERATED BY THE BSA [N,O-BIS(TRIMETHYLSILYL)ACETAMIDE] METHOD

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