Synthesis of Biaryls, Fluorenones,
Cyclopenta[<i>def</i>]phenanthren-4-ones, and
Benzophenones Based on Formal [3+3] Cyclocondensations
of 1,3-Bis(silyloxy)buta-1,3-dienes with 3-(Silyloxy)-2-en-1-ones
prepared by cyclization of 3-aryl-3-(silyloxy)-2-en-1-ones with 1,3-bis(silyloxy)buta-1,3-dienes and subsequent intramolecular Friedel-Crafts acylation of the 6-arylsalicylates thus formed. In this context, the synthesis of novel cyclopenta[def]phenanthren-4-ones is reported. In addition, the synthesis of functionalized benzophenones is reported. cyclizations - fluorenones - regioselectivity - silyl