Hydroxy-16α,17α,21-trimethyl-5-en-20-one was synthesized from 3α-acetoxypregna-5,16-dien-20-one and characterized by elemental analysis, 1H NMR, MS and IR. 16α,17α-Dimethyl steroid was formed by treatment of 3β-...Hydroxy-16α,17α,21-trimethyl-5-en-20-one was synthesized from 3α-acetoxypregna-5,16-dien-20-one and characterized by elemental analysis, 1H NMR, MS and IR. 16α,17α-Dimethyl steroid was formed by treatment of 3β-acetoxypregna-5,16-dien-20-one with methylmagnesium bromide, followed by reaction of the resulting 17(20)-enolate with methyl iodide. The main by- products were 3β-hydroxy-16α,17α-dimethyl-5-en-20-one. LHDMS([(CH 3) 3Si] 2NLi) and LDA([(CH 3) 2CH] 2NLi) were chosen as proper reagents for 21-position alkylation. The almost quantitative conversion of 16α,17α-dimethyl corticosteroid was achieved and the highest yield of the 16α,17α,21-trimethyl corticosteroid was 78%. The optimum reaction temperature was -20 ℃ for 16α,17α- dialkylation and was -50 ℃ for 21- position alkylation.展开更多
The first total synthesis of （+）-5α-hydroxy-isopterocarpolone （1）, an oxygenated eudesmane isolated from Chinese folk medicine Artemisia eriopoda, starting from （+）-dihydrocarvone（2） was described. Compound 4...The first total synthesis of （+）-5α-hydroxy-isopterocarpolone （1）, an oxygenated eudesmane isolated from Chinese folk medicine Artemisia eriopoda, starting from （+）-dihydrocarvone（2） was described. Compound 4 was stereoselectively prepared from compound 2 in three steps according to reference-. The treatment of tosylhydrazone 5, which was formed via the reaction of compound 4 and TsNHNH2 catalyzed by BF3-5Et2O, with an excess of n-butyllithium gave triene 6. Oxidation of triene 6 with singlet oxygen afforded the desired endo-peroxide 7 as a single product. Reductive cleavage of peroxide 7 with K2CO3 gave α-rotunol 3, a natural eudesmane firstly isolated in 1969. Hydrolysis of α-rotunol 3 with 10% sulfuric acid afforded （+）-5α-hydroxy-isopterocarpolone （1）. The structures of all the compounds were confirmed by IR, MS and NMR spectra.展开更多
文摘Hydroxy-16α,17α,21-trimethyl-5-en-20-one was synthesized from 3α-acetoxypregna-5,16-dien-20-one and characterized by elemental analysis, 1H NMR, MS and IR. 16α,17α-Dimethyl steroid was formed by treatment of 3β-acetoxypregna-5,16-dien-20-one with methylmagnesium bromide, followed by reaction of the resulting 17(20)-enolate with methyl iodide. The main by- products were 3β-hydroxy-16α,17α-dimethyl-5-en-20-one. LHDMS([(CH 3) 3Si] 2NLi) and LDA([(CH 3) 2CH] 2NLi) were chosen as proper reagents for 21-position alkylation. The almost quantitative conversion of 16α,17α-dimethyl corticosteroid was achieved and the highest yield of the 16α,17α,21-trimethyl corticosteroid was 78%. The optimum reaction temperature was -20 ℃ for 16α,17α- dialkylation and was -50 ℃ for 21- position alkylation.
文摘The first total synthesis of （+）-5α-hydroxy-isopterocarpolone （1）, an oxygenated eudesmane isolated from Chinese folk medicine Artemisia eriopoda, starting from （+）-dihydrocarvone（2） was described. Compound 4 was stereoselectively prepared from compound 2 in three steps according to reference-. The treatment of tosylhydrazone 5, which was formed via the reaction of compound 4 and TsNHNH2 catalyzed by BF3-5Et2O, with an excess of n-butyllithium gave triene 6. Oxidation of triene 6 with singlet oxygen afforded the desired endo-peroxide 7 as a single product. Reductive cleavage of peroxide 7 with K2CO3 gave α-rotunol 3, a natural eudesmane firstly isolated in 1969. Hydrolysis of α-rotunol 3 with 10% sulfuric acid afforded （+）-5α-hydroxy-isopterocarpolone （1）. The structures of all the compounds were confirmed by IR, MS and NMR spectra.
