Two New Diterpene Alkaloids from the Roots of Spiraea japonica var. Acuta

Spiraea japonica L. (Rosaceae) is widely distributed in Yunnan Provence, P. R. China. Previous chemical investigations on S. japonica and its varieties have led to the report of 7 new atisane-type diterpenoids and 38 new diterpene alkaloids of atisine- and hetisine-type1-11. This paper describes the isolation and structure elucidation of two new diterpene alkaloids named spiratines A and B (1-2). Their structures were elucidated on the basis of 1D and 2D NMR experiments (HMQC, HMBC, 1…     

Crystal and Molecular Structure of N-(1-Ethoxycarbonyl- ethyl)1-Ethoxycarbonylmethyl-3-ethyl-1,2,3,4- tetrahydro-4-oxo-1,3,2-benzodiazaphosphorin- 2-carboxamide 2-Oxide

1 INTRODUCTIONOrganophosphorus compounds are ubiquitous in nature and they have broad applications in the fields of agriculture and medicine. During the past two decades, (-ketophosphonates and their derivatives have attracted considerable attention because these compounds are endowed with special physical, chemical and pharmacological properties due to the proximity of the carbonyl and the phosphoryl groups[1～6]. For example, it is well known that phosphonoformic acid (PFA) is effectiv…     

Two New Steroidal Saponins from Diuranthera inarticulata

There are only three species in the genus Diuranthera (Liliaceae), which is endemic in the southwest of China1. Four steroidal saponins, diuranthosides A-C and chloromalo-side A were isolated from the fresh roots of D. major. This paper deals with the structure elucidation of two new steroidal saponins, diuranthosides D and E, which were isolated from the methanolic extract of whole plant of D. inarticulata Wang et K. Y. Lang.Diuranthoside D (1), [(]-38 (c 0.08, pyridine), afforded galac…     

Study on Phase Equilibrium Properties for CO_(2+) Cosolvent Binary Systems

Recently, the application of supercritical fluid technology is very interested, and it is applied in many areas for its special properties. The performance of supercritical fluid (SCF) as a solvent can be greatly affected by addition of an entrainer to the system. An entrainer can be added to a supercritical fluid to enhance its solvent strength and/or selectivity. Critical point data for these dilute supercritical fluid-cosolvent systems are imperative for the design of efficient separation …     

Three New Coumarins from Micromelum integerrimum

Micromelum integerrimum (Rutaceae) is a shrub growing in Yunnan Province. Leaves and barks of this plant have been used for the treatment of dysentery, and arthritis1. Previous researches revealed that this plant contained coumarins2-8. Micromelin, the main chemical constituent of this plant, showed significant inhibition against leukaemia P-388 cell line (T/C 149% at 10 mg/kg) but was inactive in lower doses, and also showed significant activity (T/C 228% at 1.25 mg/kg) against Lewis lung…     

H-Bonding Self-assembled Template-directed Synthesis of a Reactive Amide-bridged Ladder Polyvinylsiloxane

Ladder polysiloxanes (LPS) including both oxygen-bridged ladder polysilsesquioxanes (LPSQ) and organo-bridged ladder polysiloxanes (OLPS) are very important materials because of their excellent properties1. Adrianov et al. in 1960 attempted to prepare 1, …     

The Inclusion Interval of Basic Coneigenvalues of a Matrix

In this paper,a compound-type inclusion interval of basic coneigenvalues of(com- plex)matrix is obtained.The corresponding boundary theorem and isolating theorem are given.     

CONSTRUCTION OF SOLUTIONS TO M-D RIEMANN PROBLEMS FOR A2×2 QUASILINEAR HYPERBOLIC SYSTEM

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A Novel Synthesis of (-)-10-epi-α-Cyperone

The eudesmane derivative, (-)-10-epi-α-cyperone 1, is widely used as a chiral starting material for the synthesis of other fused-ring sesquiterpenes1. The first synthetic work was reported by Howe and co-workers via condensation of (+)-dihydrocarvone 2 with 1-diethylaminopentan-3-one methiodide in 32% yield2. Previously, our group reported the synthesis of compound 1 by treating ketone 2 with ethyl vinyl ketone (EVK) directly under different conditions1a, but the yields were not satisfacto…     

石墨炉内石墨探针表面上的原子化机理研究 Ⅳ钒的原子化机理

本文通过X-射线衍射分析(XRD),扫描电子显微镜分析(SEM),化学分析光电子能谱分析(ESCA),并结合原子吸收测量,研究了钒在普通石墨管中石磨探针表面上发生的固相化学反应。结果表明,钒化合物在灰化阶段即可转化为热稳定性较高的碳化物,原子化的最后步骤为碳化物的热分解。