Benz a anthracene antibiotics

Danishefsky et al. succeeded in preparing the benz[a] anthracene core structure 111 of angucycline antibiotics by performing a benzannulation reaction with the cycloalkynone 109 [69]. Deprotonation of the naphthoquinone 110 with DBU yields the desired anthraquinone 111 (Scheme 49). 

In the laboratory of S.J. Danishefsky, the synthesis of antibiotics containing the benz[a]anthracene core structure was... 

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