Natural diaryl ethers
In this review, on the basis of an analysis of voluminous literature material on natural phenolic compounds belonging to various structural types, the interrelationship between the dimeric molecules formed as the result of the oxidative coupling of the corresponding monomeric compounds is considered.
Structure of the lichen depsidone gangaleoidin
As a result of degradative, spectroscopic, and synthetic evidence the structure of the lichen depsidone gangaleoidin is revised to methyl 2,4-dichloro-3-hydroxy-8-methoxy-1,6-dimethyl-11-oxo-11H-dibenzo [b,e][1,4]dioxepin-7-carboxylate. Gangaleoidin was degraded to methyl 3-(2-methoxycarbonyl-5-methoxy-3-methylphenoxy)-4,6-dimethoxy-2-methylbenzoate (10), which was synthesised in 70% yield by Ullmann reaction between methyl 2-bromo-4-methoxy-6-methylbenzoate (22) and methyl 3-hydroxy-4,6-dimethoxy-2-methylbenzoate (30). The bromination of methyl dihydro-orsellinate(23) was studied.
Application of attribute recognition method for evaluating on sustained developmental degree of water resource systems.
Taking Ping Ba area as an example, this paper explores the method of comprehensive evaluation on sustained developmental extent of water resources systems and sets up an evaluation model by applying the attribute recognition theoretical model The result shows that it is coherence to the result of the fuzzy comprehensive evaluation method, meanwhile, this method is easy and understood, and it suit for evaluating on system quality with standardsKey words: water resources systems; attribute recognition theoretical model; fuzzy comprehensive evaluation method