First Asymmetric Total Synthesis Of (S)-Ethyl 3-O-acetylniduloate & Studies On The Synthesis Of Coriandrone B

This thesis aims at the studies on First asymmetric total synthesis of (S)-Ethyl 3-O-acetylniduloate and studies on the synthesis of Coriandrone B. It is divided into three chapters as follows:Chapter 1. First Asymmetric total synthesis of (S)-Ethyl 3-O-acetylniduloateThe important intermediate aldehyde 7 was synthesised from commercially available 4-hydroxybenzaldehyde 2 in five steps. Asymmetric alkylation of aldehyde 7 with (-)-5-allydiisopinocampheylborane under Brown's conditions afforded homoallylic alcohol 8. Treatment of 8 with Ac₂O in pyridine provided the corresponding ester 9. Ozonizing of the olefin ester 9 and subsequently reducing it with Ph₃P afforded aldehyde 10. Further oxidation of 10 with m-Chloroperbenzoic acid and esterification of 11 gave the ester 12. Afterwards the benzyl group of 12 was removed with Raney Ni- catalyzed hydrogenation in CH₃OH, the title compound 1 was obtained. The spectra data for the 1 was coincide with those for the natural compound. The stereochemistry was addressed by asymmetric alkylation with B-allydiisopinocamphenylboran under Brown's conditions.Chapter 2. Studies on the synthesis of Coriandrone BA development of 3-hydroxydihydrobenzopyran and 3, 4- dihydroisocoumarine was simplely introduced;The asymmetric synthetic route for Coriandrone B was designed. The synthesis of the key intermediate 23 from commercially available 3, 5-dihydroxybenzoic acid as starting material was achieved in eleven step;The model route was accompolished to test the feasibility of the asymmetric synthetic route for Coriandrone B.Chapter 3. A review on asymmetric expoxidation of unfunctionalized olefines catalyzed by salen-Mn(â…¢).This review covered the development, the mechanism, and application in natural products total synthesis of the asymmetric expoxidation of unfunctionalized olefines catalyzed by salen-Mn(â…¢). The preparation and the relationship between enantioselectivity and structure of salen-Mn(â…¢) were described in deta.