NaIO_4-Catalyzed Bromination of the Aromatic Ring of Lappaconitine

Lappaconitine 1, a bisnorditerpenoid alkaloid, was isolated from many plants of Aconitum species such as A. barbatum var. pulerulum and A. sinomontanum (Ranunculaceae)1-3, and used clinically for treatment of analgic disease as a nonaddicted drug in China4, and as an antiarrythmic in Uzbekistan5. In order to search for high activity, low toxicity compounds, we have carried out the structure modifications of lappaconitine. In this case, an attempt to induce the oxygenated group at C-10 in 1 b…     

A New Norditerpene from Miliusa balansae Finet et Gagnep

The plant Miliusa balansae Finet et Gagnep. is used in Chinese folk medicine for different symptom such as gastropathy and glomerulonephropathy. There is no report about its chemical investigation. In this study a new norditerpene with novel skeleton, named miliusate (1) was isolated, and its structure was established by spectral evidence.Compound 1 was obtained as white flaky crystal, mp 89-91(C; Its molecular formula C20H26O5 was provided by quasi-molecular ion [M+H]+ at m/z 347.17970 (c…     

An Improved Synthesis of trans-3,3b,4,9b,10,11-Hexahydro -6-methoxy-9b-methyl-7- (1-methylethyl) phenanthro {1,2-c[furan-1,5-dione]}

The diterpenoid triexpoxides lactone triptolide is a potent antileukemic, antiflammatory, immunosuppressive and antifertile principle of Tripterygium wilfordii Hook f.1,2. Many methods of synthesis of this compound have been reported in which trans-3,3b,4,9b,10, 11-hexahydro-6-methoxy-9b-methyl-7- (1-methylethyl) phenanthro {1,2-c [furan-1,5- dione]} 4 was an important intermediate. In one reported synthesis, compound 4 was obtained by CrO3/AcOH oxidation of triptophenolide methyl ether 1, b…     

Theoretical Study of the Sensitivity-Improvement Effect of Phosphoryl Group in Mass Spectrometry of Small Peptides

Mass spectrometry plays an important role in peptide sequencing since the invention of soft ionization techniques, such as fast atom bombardment (FAB), electrospray (ESI) and matrix-assisted laser desorption/ionization (MALDI). In our previous work, it was found that phosphorylation on the N-terminal of small peptides could enormously improve their sensitivity in FAB-MS1.To understand the sensitivity-improvement effect of phosphoryl group, the energies for the protonation of glycylglycin…     

Quantized Nanocrystalline CdTe Thin Films

Size quantized nanocrystalline semiconductor thin films have attracted considerable interest in the photoelectrochemical studies1,2. In this paper, we report a pronounced size quantization in nanocrystalline CdTe thin films which is less extensively studied.Nanocrystalline CdTe thin films were electrodeposited on conducting glass by asymmetric rectangular pulse in dimethylsulfoxide solution containing 6 mmol/L Te, 0.75 mmol/L Cd(ClO4)2, 18 mmol/L triphenylphosphine and 0.1 mol/L LiClO4 a…     

Diastereoselective Michael Addition of (4''''S)-Ethyl-3-(2'''',2''''-Dimethyl-1'''',3''''- dioxolan-4''''-yl) acrylate with Furyl Lithium

Recently we reported that the diastereoselective intramolecular [4+3] cycloaddition of 4 led to the formation of cycloadduct 5 as the only isolated isomer in 50% yield. The chiral C-3 of compound 4 could be used to direct the stereochemical course of [4+3] cycloaddition enabling the control of the relative stereochemistry between three contiguous asymmetric centers in adduct 51. The stereogenic center at C-3 of 4 was constructed by the asymmetric Michael addition of (, (-unsaturated ester 2 w…     

A New Ceramide from the Basidiomycetes Armillaria mellea

As one part of our study on the bioactive metabolites of the higher fungi in Yunnan Province, the chemical constituents of Armillaria mellea (Tricholomataceae) collected at Zhong Dian in Yunnan Province have been investigated. The present report deals with the structural elucidation of a new ceramide 1, named armillaramide, isolated from the AcOEt extract of the fruiting bodies of this fungus.Figure 1 The structure of armillaramide 1Compound 1, white amorphous powder, mp 113(117(C, [(] + …     

Surface Modification of Nanometer Silica by N, N''''-dicyclohexyl- carbodiimide Mediated Amidation

Nanometer silica has gained ever more attention for its superior properties over conventional micrometer particles and has been widely used as a filler in the manufacture of paints, rubber, plastics and so on1. However it is difficult to get silica mono- dispersed in the matrix due to heavy agglomeration. Surface modification through organic reactions is an efficient way to improve the dispersibility and compatibility with the matrix, thus improving the mechanical properties of the composite…     

Isomerization of 4-Amino-6-tert-butyl-3-methylthio-1,2,4-triazin-5(4H)-one with Base

4-Amino-6-tert-butyl-3-methylthio-1, 2, 4-triazin-5 (4H)-one I, named as Metribuzin1, is an excellent selective herbicide. In the course of studying the reaction of I, we have found an unexpected reaction. We have attempted to prepare 6-tert-butyl- 4-methylamino-3-methylthio-1, 2, 4-triazin-5 (4H)-one II from I with methyl iodide in the presence of sodium hydroxide in aqueous methanol, surprisingly, instead of II the product III 4-amino-6-tert-butyl-3, 4-dihydro-2-methyl-3-thioxo-1, 2, 4-…     

Study on the Ring Eulargment Reaction: Synthesis of 7,8,13, 13a-tetrahydroisoindolo[1,2-b][3]benzazepine and 5,6,8,9,14,14a-hexahydroisoquino[1,2-b][3]benzazepine

In our research on the ring enlargement of certain N-heterocycles, a general procedure for the ring enlargement with the insertion of an extra -CH2- was improved and shown in Scheme I1.Scheme IThe procedure had been carried out with such N-heterocycles as 2-methyl-1,2,3,4-tetrahydroisoquinoline2, tetrahydroberberine and strychnine3 with expected results. Thus, the procedure shown in Scheme I provides a new approach to the synthesis of larger N-heterocycles.Isoindolo[1,2-b][3]benzazepines a…