Eremophilenolides from Cacalia Roborowskii

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.

Eremophilane Sesquiterpenes from Cacalia Roborowskii

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.

A New Approach to the Construction of Pyrrolizidine and Indolizidine Skeleton: Enantioselective Synthesis of (1S, 7aS)-1-hydroxypyrrolizidine and (1S, 8aS)-1-hydroxyindolizidine

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.

The Formal Stereoselective Synthesis of(+)-Preussin

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.

The Stereoselective Formal Synthesis of (-)-Slaframine

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.

Synthesis of the optically pure 5,5"-dihydroxy-7,7"-dimethoxy-8,8"-biflavone and its derivatives

(+/-)-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.

Microbial-chemical routes to R and S-denopamine a useful drug for congestive heart failure

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.

Lipases catalyzed acetylation of meso-2,4-dimethyl-1,5-pentanediol and the synthesis of Prelog-Djerassi lactone

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.