Synthesis of 9-substituted 1,8-dioxooctahydroxanthenes by using diethyl ethoxymethylenemalonate as a double Michael acceptor synthon

Tandem Michael addition/elimination/Michael addition/cyclization reactions of diethyl ethoxymethylenemalonate as a double Michael acceptor with cyclic β-diketones furnished novel 9-substituted 1,8-dioxooctahydroxanthenes.