Synthesis of 9‐Substituted‐1,8‐Dioxooctahydroxanthenes by an Efficient Iodine‐Catalyzed Cyclization

Abstract

Abstract New 1,8‐dioxooctahydroxanthenes with substituents in the 2‐, 3‐, and 9‐positions were obtained by cyclization with iodine from tandem Michael/Michael adducts. The X‐ray molecular structure of the methyl 2‐(1,8‐dioxo‐2,3,4,5,6,7,8,9‐octahydro‐1 H ‐xanthen‐9‐yl)acetate ( 3a ) was solved and shows the parallel laminae packing of these molecules. Furthermore, we reported the structure of intermediate 4 isolated from this reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)