Studies On The Synthesis And Catalytic Performance Of Novel Isosteviol Derivatives

In this thesis27structural novel isosteviol derivatives were synthesized fromisosteviol, a natural product with rigid skeleton, in order to constructure somemulti-functionalized bioactive or synthetic useful compounds,16of them are notfound in the literature. The new compounds were obtained via hydroxyl methylation,oximation, oxidation, reduction, etc, on the structural modification and transformationand the introduction of hydroxyl groups, oxime, heterocyclic, thiourea, and α,β-unsaturated carbonyl subunit. The structures of the new compounds wee characterizedby IR,1H NMR,13C NMR and HRMS. In addition, the catalytic behaviors for theasymmetric Petasis reaction were examined with15-hydroxymethyl-16-thiourealsubstituted Isosteviol as the organo catalyst. On the other hand, some tridentate typecoordination group containing Isosteviol were also synthesized as chiral ligands, inorder to test their coordination catalysis performance with different metal ions forsome organic reactions, such as the Henry reaction. The specific researches are asfollows:1.Synthesis of C ring expanding isosteviol derivatives and its allyl alcoholizationWith isosteviol3as the starting material, the15-α-hydroxymethyl-16-β-hydroxyisosteviol4was obtained easily via the “one-pot” two step process of aldol reactionand hydrogen transformation. After transformation of4to its tosyl ester5, compound7, which possesses both a formyl group and a vinyl group, was synthesized by treatingthe reaction mixture with NaOH. Condensation of compound6with aniline caused asequential cyclo addition and a rearrangement to form the C ring expanding isosteviolderivatives7, which was ransferred to its corresponding allyl alcohol type derivativeafter oxidation with selenium dioxide. 2.The synthesis of15-α-hydroxymethyl-16-α-thioreal isosteviol derivatives and theevaluation of their catalytic behaviors in the Petasis reaction.Compound6was transformed to its oxime with hydroxylamine in the presenceof NaHCO3,which was then underwent an intramolecular1,3-dipole addition togenerate an oxazloe derivative under the catalysis of boron trifluoride. Theheterocycle was opended via R-Ni catalyzed hydrogenolysis to generate thecooresponding15-hydroxymethyl--16-α-amino Isosteviol derivatives16, whichreacted then with different phenyl isothiocyanate to form nine15-α-hydroxymethyl-16-α-thioreal isosteviol derivatives. The catalytic performances in theasymmetric Petasis reaction were also studied, though the results obtained were notsatisfactory in their stereoselectivities.3、The synthesis of15-α-hydroxymethyl-16-α-aminolated isosteviol derivatives andtheir coordination catalysis performances with different metal ions in the Henryreaction.Reacting of the amino alcohol16with the salicylaldehyde or the2-pyridineformaldehyde, the corresponding imines,25and27, were obtained, respectively.Reduction of compound26by sodium borohydride to get the tridentate Isosteviolderivative as chiral ligands, in order to test their coordination catalysis performance with different metal ions for some organic reactions. The catalytic performances inthe asymmetric Henry reaction were also evaluated.