Studies On The Asymmetric Total Synthesis Of Natural Eudesmanes And Cadinenes

This thesis aims at the studies on the asymmetric total synthesis of natural eudesmane and cadinene sesquiterpenes.It consists of the following four parts:Introduction Part:The background,intention and significance of the research of this thesis were introduced concisely.PartⅠ:The first asymmetric total synthesis of the enantiomers of natural 1β-hydroxy-eudesma-5,11-diene and 1β,11-dihydroxy-5-eudesmeneStarting from(+)-dihydrocarvone,using a substrate controlled hydromethylation to introduce the C-1 oxygenated group,a regioselective aldol reaction and a alkaline Robinson cyclization to assemble the decaIin skeleton,the first asymmetric total synthesis of the enantiomers of natural 1β-hydroxy-eudesma-5,11-diene and 1β,11-dihydroxy-5-eudesmene was accomplished.And the stereochemistry of the C-4 methyl group in natural 1β,11-dihydroxy-5-eudesmene was revised fromαtoβ.PartⅡ:The asymmetric total synthesis of cadinene sesquiterpenes.1.The basic configuration features and classes of cadinene sesquiterpenes were introduced concisely.2.The efficient synthesis of muurolane-type cadinenes was studied.Starting from R-(-)-carvone,using ring closing metathesis(RCM)reaction and allylic diazene rearrangement as the key steps,the first total synthesis of natural 10β-hydroxy-4-muurolen-3-one and the enantiomer of natural 10α-hydroxy-4-muurolen-3-one was accomplished.3.A highly efficient approach to the synthesis of the trans cadinane skeleton starting from R-(-)-carvone was developed.Using RCM reaction and a modified allylic diazene rearrangement as the key steps,the first asymmetric total synthesis of 4α,5α,10β-trihydroxycadinane and 4β,5α,10β-trihydroxycadinane was accomplished,the incorrect structural assignment of the natural cadinane made by Ahmed A.Mahmoud and et al.was revised and the absolute configuration of natural 4β,5α,10β-trihydroxycadinane was established.PartⅢ:ReviewIn this part,taking eudesmane-type and cadinene-type bicyclic sesquiterpenes for example,some published methods for construction of decalin ring system were reviewed.