Studies On Synthesis Of Anti-HIV Natural Products Biyouyanagin A & B And Fuscins

This dissertation consisted of three parts:Chapter 1:Total synthesis of Anti-HIV natural product Biyouyanagin AUsing palladium-catalyzed asymmetric allylic alkylation as key reaction, we constructed two adjacent quaternary carbon centers with high enantioselectivity and diastereoselectivity. To improve the selectivity of the reaction, ligand (R, R)-L2 was used to instead of (R, R)-L1 and the desired product was obtained with higher diastereoselectivity (26:1) and better enantioselectivity (99% ee), the ee value from 95% up to 99%, dr value increased from 8.7:1 to 26:1. This strategy has enabled the concise and efficient total syntheses of natural Hyperolactone C and (-)-Biyouyanagin A from benzaldehyde and methyl acetoacetate in only six and seven steps, respectively. The corresponding overall yields were 20% and 8%.The unnatural enantiomer ent-Hyperolactone C and (+)-Biyouyanagin A were also prepared by simply switching the chiral ligand in the Pd-AAA reaction and by changing the coupling partner in the final photoinduced [2+2] cycloaddition reaction.To extend research of asymmetric allylic alkylation on the substrate scope, the use of L2 as a ligand made ee values were all up to 99% and dr value of up to 56:1.Chapter 2:Study on the total synthesis of natural products Biyouyanagin B and other related spirolactone natural productsStudy on the synthesis of natural products Biyouyanagin B and its structure exploration. Using asymmetric allylic alkylation (Method C), benzaldehyde and methyl acetoacetate were used as starting materials to synthesize 4-epi-Hyperolactone C, natural products Hyperolactone D and 4-hydroxyhyperolactone D, meanwhile the absolute configuration of 4-Hyperoxyhyperolactone D was identified.Structure determination of Biyouyanagin B is not accurate in the separation literature and the corrected structure exploration is ongoing.With our research methods, Study on the total synthesis of Hyperolactone A and Hyperolactone B is in process.Chapter 3:Total synthesis of Anti-HIV natural product FuscinsWith gallacetophenone as the starting material and the microwave-assisted tandem ortho-Claisen/Cope rearrangement as a key step, then a key common synthetic intermediate compound (6) was achieved. Followed by double bond rearrangement and the double bond cutting off. Then a concise,9-step synthesis of Fuscinarin has been achieved in a 33.4% overall yield. The synthesis of Fuscin and Dihydrofuscin also has been achieved with a common synthetic intermediate compound (6).