Studies On The Asymmertric Total Synthesis Of γ-Rubromycin

This thesis is specific to the studies on the asymmertric total synthesis of natural products γ-Rubromycin.The progress on the total synthesis of Rubromycins was summarized firstly.The main structural features of these compounds are: naphthoquione fragment and isocoumarin precursor are connected through a [5,6] spiroketal skeleton.On the basis of our previous works toward the construction of [5,6] spiroketals,a new route for the asymmetric protocols was designed for the synthesis of the key fragments isocoumarin and naphthoquione.For isocoumarin fragment,the synthesis of precursor fragment 2-51 from 2-43 was completed over 9 steps.The synthesis of naphthoquione fragment was a great challenge because its electron-rich high regioselective and highly oxidized properties.3 new routes was designed to synthesize the naphthalene fragment via a Diels-Alder reaction.Starting from 2-15,the naphthoquinone diene precuisor 2-24、2-25 and 2-37 were obtained successfully.According to the traditional route,we successfully obtained the γ-Rubromycin as a racemate.Correlational research on asymmertric synthesis of [5,6] spiroketal skeleton is still on working.