Studies toward the total synthesis of Sch 202596, an antagonist of the galanin receptor subtype GalR1: synthesis of geodin, the spirocoumaranone subunit of Sch 202596

An efficient synthesis of (±)-geodin [(±)-2] corresponding to the spirocoumaranone subunit of Sch 202596 (1) was accomplished in a convergent manner by utilizing coupling reaction of the aryl aldehyde 5 with the aryl bromide 6 and oxidative spirocyclization of the benzophenone 4 as the key steps. The aromatic segments 5 and 6 were prepared from commercially available methyl 3,5-dihydroxybenzoate (7) and 5-methylresorcinol (8), respectively.