Synthesis and formation mechanism of ocotillol and its epimer / 中国药科大学学报

ABSTRACT

@#Ocotillol(3)and its epimer(4)have been synthesized from 20(S)-protopanaxatriol ［20(S)-PPT］ via two routes, and their formation mechanism has been speculated. Route 1 Compounds 3 and 4 were obtained from 20(S)-PPT by oxidation with m-CPBA at the yield of 44. 1% and 28. 6%, respectively. Route 2 Compounds 3 and 4 were prepared from 20(S)-PPT by acetylation, oxidation and saponification at the yield of 16. 4% and 16. 2%, respectively. The formation mechanism of compounds 3 and 4 is speculated as below 1)The chemical environments of both sides of C24(25)double bond in 20(S)-PPT are different due to the existence of intramolecular hydrogen bond, which led to the different oxidation ratio of the two sides, and the different yields of compounds 3 and 4. 2)There is not intramolecular hydrogen bond in acetylated 20(S)-PPT, and the chemical environments of both sides of C24(25)double bond are similar, which resulted in almost equal yields of compounds 3 and 4 synthesized through oxidation with m-CPBA, intramolecular SN2 and saponification.