Synthesis and some annelation reactions of 1,4-diketones

Abstract

Methods for the synthesis of 1,4-diketones are briefly reviewed. A new route to 1,4-diketones involves the Wittig reaction between the stable ylides, Ph₃PCHCOCH₃ and Ph₃PCHCOPh, and 1,2-diones, followed by seduction of the (E)-diacylethylene.     Pyrolysis of diphenacylsulphone yields a derivative of thiet 1,1- dioxide. Phenylglyoxal, acetic anhydride, and pyridine give ?dibenzoylformoin diacetate?, probably by a benzoin condensation involving catalysis of a novel type.     Annelation reactions of 1,4-diketones are reviewed. The reactions with indole have been extended. The structures of the products from pyrogallol (trihydroxy-naphthalenes), and from quinol and 1,4- dihydroxynaphthalene (anthraquinones) have been established.