Toward a total synthesis of stigmatellin; an unproductive C-1′–C-2′ disconnection

Although the lithio derivative of the dimethylchromone 6c could be condensed with reactive organic electrophilic species and iodine to give, respectively, homologated at C-1′ (stigmatellin numeration) chromones and the iodide 6a, it proved impossible to convert efficiently either 6a or 6c into stigmatellin 1a by an anionic alkylation process.