The First Synthesis of the ABC-Ring System of ‘Upenamide Jan Peter Schmidt Sandra Beltrán-Rodil Rhona J. Cox Graeme D. McAllister Mark Reid Richard J. K. Taylor 10.1021/ol701772d.s002 https://acs.figshare.com/articles/journal_contribution/The_First_Synthesis_of_the_ABC_Ring_System_of_Upenamide/2983858 The first synthetic route to the spirooxaquinolizidinone core (ABC core) of the macrocyclic marine alkaloid ‘upenamide (<b>1</b>) has been developed. All five stereocenters were introduced with complete stereocontrol. The hydroxyl group at C-11 was introduced by a regio- and stereoselective SeO<sub>2</sub>-mediated allylic oxidation. The spirocyclic skeleton was formed by a stannous chloride induced deacetalization−bicyclization procedure. Further stereocenters were introduced by an enzymatic desymmetrization and by incorporation of an (<i>S</i>)-malic acid derived building block. 2007-09-27 00:00:00 alkaloid stereoselective stereocenter upenamide acid building block desymmetrization allylic ABC core spirooxaquinolizidinone core hydroxyl group stannous chloride First Synthesis oxidation spirocyclic skeleton regio incorporation SeO marine stereocontrol UpenamideThe macrocyclic deacetalization procedure