From the extracts of the roots of Cacalia roborowskii (Maxim) Ling, five new eremophilenolides were isolated and their structures identified as 8 beta, 10 beta-dihydroxy-6 beta-methoxyleremophilenolide (1), 3 beta-ace...From the extracts of the roots of Cacalia roborowskii (Maxim) Ling, five new eremophilenolides were isolated and their structures identified as 8 beta, 10 beta-dihydroxy-6 beta-methoxyleremophilenolide (1), 3 beta-acetoxyl-8 beta, 10 beta -dihydroxy-6 beta-methaxyeremophilenolide (2), 3 beta-angeloyloxy-8 beta-, 10 beta-dihydroxy-6 beta-methoxyeremophilenolide (3), 3 beta-(2-methylbutyryloxy)-8 beta, 10 beta-dihydroxy-6 beta-methoxyeremophilenolide (4), and 8 beta-hydroxy-6 beta-methoxyeremophil-7(11), 9-dien-8, 12-olide(5), based on 1D and 2D NMR experiments.展开更多
Four new eremophilane type sesquiterpenes were isolated from the roots of Cacalia roborowskii (Maxim) Ling. Their structures were established as 8-oxo-eremophila-6, 9-dien-12-oic acid (1), 3 beta-acetoxyl-8-oxo-eremop...Four new eremophilane type sesquiterpenes were isolated from the roots of Cacalia roborowskii (Maxim) Ling. Their structures were established as 8-oxo-eremophila-6, 9-dien-12-oic acid (1), 3 beta-acetoxyl-8-oxo-eremophila-6, 9-dien-12-oic acid (2), 3 beta-angeloyoxyl-8-oxo-eremophilad, 9-dien-12-oic acid (3) and 3 beta-(2-methylbutyryloxyl)-8-oxo-eremophilia-6,9-dien-12-oic acid (4) by means of 1D and 2D NMR spectroscopy.展开更多
The stereoselective synthesis of (-)-slaframine has been achieved by utilizing the Sharpless asymmetric epoxidation of divinylcarbinol (2) and the regio-selective dihydroxylation of compound 4 as the key steps.
A new approach to the construction of pyrrolizidine and indolizidine skeleton was described. By employing this cyclization method the synthesis of (1S. 7aS)-1-hydroxypyrrolizidine (1a) and (1S. 8aS)-1-hydroxyindolizid...A new approach to the construction of pyrrolizidine and indolizidine skeleton was described. By employing this cyclization method the synthesis of (1S. 7aS)-1-hydroxypyrrolizidine (1a) and (1S. 8aS)-1-hydroxyindolizidine (1b) was achieved by treatment of the trimesylate 6a or 6b with aqueous ammonia in the presence of KaCO(3) (or Cs2CO3) in one-pot fashion.展开更多
The stereoselective synthesis of (+)-preussin has been achieved by utilizing the Sharpless asymmetric epoxidation of the divinylcarbinol (3) and the oxidative cyclization of 9 with PDC as the key steps.
(+/-)-5,5 '-Dihydroxy-7,7 '-dimethoxy-8,8 '-biflavone ((+/-)-1) was resolved into its optically pure forms via the formation and recrystallization of its (2R)- and (2S)-1-(4-toluenesulfonyl)prolylate, and ...(+/-)-5,5 '-Dihydroxy-7,7 '-dimethoxy-8,8 '-biflavone ((+/-)-1) was resolved into its optically pure forms via the formation and recrystallization of its (2R)- and (2S)-1-(4-toluenesulfonyl)prolylate, and the methylated derivatives of (+)- and (-)-1 were also prepared. The absolute configurations of all these 8,8 '-biflavones have been confirmed by their CD spectra.展开更多
Both enantiomers of denopamine were synthesized using microbial-chemical approach via bioreduction of 1-(acetoxyphenyl)ketone 4(R=CH2Cl) and 5(R=CO(2)Et) with fungus Geotrichum sp. G38.
Lipase catalyzed acetylation of 2 afforded 3 with the e.e. up to 98%. Utility of 3 was illustrated by the preparation of Prelog-Djerassi lactones 7a and 7b.
文摘From the extracts of the roots of Cacalia roborowskii (Maxim) Ling, five new eremophilenolides were isolated and their structures identified as 8 beta, 10 beta-dihydroxy-6 beta-methoxyleremophilenolide (1), 3 beta-acetoxyl-8 beta, 10 beta -dihydroxy-6 beta-methaxyeremophilenolide (2), 3 beta-angeloyloxy-8 beta-, 10 beta-dihydroxy-6 beta-methoxyeremophilenolide (3), 3 beta-(2-methylbutyryloxy)-8 beta, 10 beta-dihydroxy-6 beta-methoxyeremophilenolide (4), and 8 beta-hydroxy-6 beta-methoxyeremophil-7(11), 9-dien-8, 12-olide(5), based on 1D and 2D NMR experiments.
文摘Four new eremophilane type sesquiterpenes were isolated from the roots of Cacalia roborowskii (Maxim) Ling. Their structures were established as 8-oxo-eremophila-6, 9-dien-12-oic acid (1), 3 beta-acetoxyl-8-oxo-eremophila-6, 9-dien-12-oic acid (2), 3 beta-angeloyoxyl-8-oxo-eremophilad, 9-dien-12-oic acid (3) and 3 beta-(2-methylbutyryloxyl)-8-oxo-eremophilia-6,9-dien-12-oic acid (4) by means of 1D and 2D NMR spectroscopy.
文摘The stereoselective synthesis of (-)-slaframine has been achieved by utilizing the Sharpless asymmetric epoxidation of divinylcarbinol (2) and the regio-selective dihydroxylation of compound 4 as the key steps.
文摘A new approach to the construction of pyrrolizidine and indolizidine skeleton was described. By employing this cyclization method the synthesis of (1S. 7aS)-1-hydroxypyrrolizidine (1a) and (1S. 8aS)-1-hydroxyindolizidine (1b) was achieved by treatment of the trimesylate 6a or 6b with aqueous ammonia in the presence of KaCO(3) (or Cs2CO3) in one-pot fashion.
文摘The stereoselective synthesis of (+)-preussin has been achieved by utilizing the Sharpless asymmetric epoxidation of the divinylcarbinol (3) and the oxidative cyclization of 9 with PDC as the key steps.
基金Project supported by the National Natural Science Fbundation of China
文摘(+/-)-5,5 '-Dihydroxy-7,7 '-dimethoxy-8,8 '-biflavone ((+/-)-1) was resolved into its optically pure forms via the formation and recrystallization of its (2R)- and (2S)-1-(4-toluenesulfonyl)prolylate, and the methylated derivatives of (+)- and (-)-1 were also prepared. The absolute configurations of all these 8,8 '-biflavones have been confirmed by their CD spectra.
文摘Both enantiomers of denopamine were synthesized using microbial-chemical approach via bioreduction of 1-(acetoxyphenyl)ketone 4(R=CH2Cl) and 5(R=CO(2)Et) with fungus Geotrichum sp. G38.
基金Project supported by the National Natural Science Foundation of China.
文摘Lipase catalyzed acetylation of 2 afforded 3 with the e.e. up to 98%. Utility of 3 was illustrated by the preparation of Prelog-Djerassi lactones 7a and 7b.
