The Design,Synthesis Of Chiral Catalysts Base On Ent-beyerane Diterpene Compounds

Stevioside is accessible,inexpensive,fewer calories and low toxicity that makes stevioside widely used as a ideal sweetener.Isosteviol and its derivatives which esalily obtained from stevioside by acid hydrolysis have good biological activities in hypoglycemic,antihypertension,myocardial protection,antibacterial and anti-tumor.Until now,numerous studies show that isosteviol and its derivatives have good biological activity.But it used as catalysts for asymmetric reactions is rarely reported.Isosteviol is a tetracyclic diterpeniod with beyerane skeleton and stable chiral centers provide superior chiral environment.In addition,the presences of 16-Keto group and 19-carboxyl group provide further advantage which make the isosteviol easier to modify.Therefore,it is feasible to design and composite a novel class of conjugates by combined Lewis acid(calixarene)and Lewis base(phosphine)with isosteviol to get catalyst Catl-5.The structures of Catl-3?11 and 12 are identified by 1H-NMR,13C-NMR and MS.This dissertation consist of two chapters.Chapter ? gives a review of chiral catalysts based on amino acids,cinchona alkaloids,sugars,peptides,terpenoids from 2000;In chapter ?,Catl-3 were designed and synthesised from the initial raw material isosteviol.The influence of temperature?solvent and base on reaction are investigated.Tests show that temperature has great influence on Cat3 and 12,solvent and base are factors on 11,only NaH can succeed.Catl.Catl-3 was proved to be stable at room temperature.