First Total Synthesis of 4,5-Sccoeudesmane-type and Iphionane-type Compounds-Synthesis of 4,5-Dioxo-seco-γ-eudesmol and 5β,11-Dihydroxyiphionan-4-one

4, 5-Secoeudesmane-type and iphionane-type compounds are sesquiterpenes with newcarbon skeletons found in natrual sources in recent years.1-6 The co-occurence of 4, 5secoeudesmanes, iphionanes and eudesmanes as natrual products suggests that 4, 5secoeudesmanes, iphionanes most likely are generated biogenetically tyom eudesmanes,and iphionanes are formed biogenetically by aldol reaction of 4, 5dioxosecoeudesmanes1,4,6,7 The study on the synthesis of this two kind of newsesquiterpenes has not be…