Abstract The 1: 1 intermediate generated by the addition of triphenylphosphine to dialkyl acetylenedicarboxylates is trapped by alizarin to produce alkyl 6, 11-dihydro-12-hydroxy-2, 6, 11-trioxo-2 H-naphtho [2, 3-g] chromene-4-carboxylates in good yields. When ethyl propiolate was used, the reaction afforded ethyl 6, 11-dihydro-6, 11-dioxoanthra [1, 2-d][1, 3]- dioxole-2-acetate. The reaction of dialkyl acetylenedicarboxylates, alizarin, and trialkyl ...
