Synthesis of 25-oxygenated D: A-friedooleananes: Part V-Conversion of putranjivadione (D: A-friedoolean-3,7-dione) to 25-formyl D: A-friedoolean-3-one

摘要

Structure of the natural product 25-formyl-D: A-friedoolean-3-one 1 has been established by its synthesis from putranjivadione 2. Compound 2 is converted into 7#beta#, 25-oxido-D:A-friedoolean-3#beta#-ol 4 which on treatment with lithium in ethylenediamine yields D:A-frieaoolean-3#beta#,25-diol 5 as one of the products. 5 on oxidaton with CrO_3 in pyridine affords 1.