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…     

A Case of Abnormal Bishler-Napieralski Cyclization Reaction,Leading to Form Benzyl Oxazole Derivatives

1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid is a type of naturally occurring bio-active alkaloid1. Moreover, it can be used as building block for the synthesis of other natural products containing the 1,2,3,4-tetrahydroisoquinoline moiety2. Compound 2 was an intermediate in our attempt to the total synthesis of Ecteinascidin analogs. We employed the Bishler-Napieralski reaction to prepare this product and refluxed the N-acetyl phenylalanine compound 1 in POCl3/benzene. However, we fail…     

A New Sesquiterpene Lactones Glucoside from Notoseris psilolepis

As a part of an investigation on plant of the genus Notoseris (Asteraceae), an endemic genus of seed plants of China1, we studied the chemical constituents of N. psololepis Shih. A new sesquiterpene lactone glucoside, named notoserolide C (1) was isolated from the methanolic extract of the whole plant of N. psilolepis by repeated column chromatography (MCI GEL, normal and reversed phase silica gel). This compound showed antibacterial activity against Bacillu cereus.Figure 1. The key HMB…     

A New Indole Alkaloid from Limonia Crenulata

Limonia crenulata Roxb. (Rutaceae), a small tree widely distributed in dry warm regions of southeastern Asia, has been reported to have antiepileptic, purgative and sudorific effects and is used for colic trouble and cardialgia1. Various parts of this plant have been employed in indigenous medicine. Our investigation on its stems led to the isolation of one new alkaloid, crenulatine 1, together with three known ones, 4-methoxy-6- hydroxy-1-methyl-2-quinolone2, N-benzoyltyramine methyl ether2,…     

A Novel Synthesis of Dimethyl Malonate by Carbonylation of Methyl Chloroacetate Catalyzed by Cobalt Complex

Dimethyl malonate (DMM) is an important organic synthesis intermediate. Traditional synthetic method by reaction of mono-chloroacetic acid with sodium cyanide1 is poisonous and complicated. Therefore, an interest in green synthesis routes of DMM has risen greatly. The several processes for preparing DMM by carbonylation of methyl chloroacetate catalyzed by Co2(CO)8 have been reported2~5. However, Co2(CO)8 is unstable and must be prepared under high pressure (12 Mpa). Moreover, the yield…