[Effects of Different Shading Treatment and Planting Patterns on Several Main Characters and Yield of Elephantopus scaber].

OBJECTIVE: To study the growth and yield of Elephantopus scaber under different light conditions. METHODS: Several main characters and yield performances were studied under six shading treatment as well as two planting patterns. RESULTS: The plant height, leaf number, root length and root-shoot ratio were increased under moderate shading. With the increase of shading ratio, the process of Elephantopus scaber vegetative growth to reproductive growth were shortened, seed yield, dry biomass and root yield decreased as well. Among different shading treatments, dry seed-yield showed 8. 46 ~31. 10 kg/667 m2 dry biomass showed 327. 28 ~ 800. 95 kg/ 667 m2 and dry root yield showed 30. 65 ~ 70. 72 kg/667 m2. CONCLUSION: Elephantopus scaber is a light-demanding but shade-tolerant plant. The patterns of hole seeding were suggested in planting, and not more than 60% shade density may be good under plantations.

Nonracemic bicyclic lactam lactones via regio- and cis-diastereocontrolled C-H insertion. Asymmetric synthesis of (8S,8aS)-octahydroindolizidin-8-ol and (1S,8aS)-octahydroindolizidin-1-ol.

The Rh(2)(MPPIM)(4)-catalyzed intramolecular C-H insertion reaction of (S)- and (R)-1-benzyl-5-(alpha-diazoacetoxy)piperidin-2-one and (S)-1-benzyl-4-(alpha-diazoacetoxy)pyrrolidin-2-one proceeds with high regioselectivity and cis-diastereoselectivity to give good yields of chiral nonracemic bicyclic lactam lactones (BLLs). For (S)- and (R)-1-benzyl-5-(alpha-diazoacetoxy)piperidin-2-one, the regioselectivity of the C-H insertion is catalyst-dependent; for example, (S)-1-benzyl-5-(alpha-diazoacetoxy)piperidin-2-one undergoes C-H insertion at C-6 preferentially when Rh(2)(5S-MPPIM)(4) is used, but with Rh(2)(5R-MPPIM)(4), C-H insertion occurs preferentially at C-4. This effect is not observed in the reaction of (S)-1-benzyl-4-(alpha-diazoacetoxy)pyrrolidin-2-one. The utility of the BLLs as chiral building blocks in alkaloid synthesis is exemplified by the synthesis of (8S,8aS)-octahydroindolizidin-8-ol and (1S,8aS)-octahydroindolizidin-1-ol.

Asymmetric synthesis of (+)-isofebrifugine and (-)-sedacryptine from a common chiral nonracemic building block.

The stereoselective syntheses of 2-substituted and 2,6-disubstituted 3-hydroxypiperidine alkaloids, (+)-isofebrifugine and (-)-sedacryptine, from a common, functionalized nonracemic bicyclic building block are achieved, demonstrating the flexibilty of the approach.

Platelet-activating factor (PAF) receptor binding antagonists from Alpinia officinarum.

The bioassay-guided purification of ether extracts of Alpinia officinarum led to the isolation of two new compounds 6-hydroxy-1,7-diphenyl-4-en-3-heptanone (1) and 6-(2-hydroxy-phenyl)-4-methoxy-2-pyrone (4) as well as three known compounds 1,7-diphenyl-4-en-3-heptanone (2), 1,7-diphenyl-5-methoxy-3-heptanone (3), and apigenin (5). Their structures were established on the basis of spectral methods. All three diarylheptanoids 1, 2, and 3 exhibited potent PAF receptor binding inhibitory activities with an IC(50) of 1.3, 5.0, and 1.6 microM, respectively. These studies have identified diarylheptanoids as a novel class of potent PAF antagonists.

Regio- and diastereocontrolled C-H insertion of chiral gamma- and delta-lactam diazoacetates. Application to the asymmetric synthesis of (8S,8aS)-8-hydroxyindolizidine.

gamma- and delta-Lactam diazoacetates undergo efficient intramolecular C-H insertion catalyzed by Rh2(MPPIM)4 with excellent regioselectivity and cis-diastereoselectivity to provide synthetically useful bicyclic lactam lactones.

Asymmetric total syntheses of (-)-antofine and (-)-cryptopleurine using (R)-(E)-4-(tributylstannyl)but-3-en-2-ol.

The asymmetric total syntheses of the representative phenanthroindolizidine and phenanthroquinolizidine alkaloids, (-)-antofine and (-)-cryptopleurine, are described. An efficient synthetic pathway to the key intermediate 12, in enantiomerically pure form, was achieved by using a chiral building block (R)-9 and the Overman rearrangement with a total transfer of chirality. The problem of constructing the pyrrolidine and piperidine rings was successfully addressed, primarily by using a ring-closing metathesis reaction and a cross-metathesis reaction, respectively.

Synthesis of 4-acetylisocoumarin: first total syntheses of AGI-7 and sescandelin.

A practical synthetic route to 4-acetylisocoumarins and the first total synthesis of AGI-7 (5) and sescandelin (4) are described. The readily available homophthalate 8 was transformed to the vinylogous amide ester 13 in high overall yield. Upon treatment of 13 with refluxing aqueous formic acid, the desired 4-acetylisocoumarin (5) and its regioisomer 3-methyl-4-formylisocoumarin (17) were produced in a 3:1 ratio. After separation of the desired product (5) from the unwanted minor isomer, the enantioselective reduction of AGI-7 by borane in the presence of Corey's (S)-oxazaborolidine reagent afforded (+)-sescandelin (4) with a 93% ee.