Diphenyl oxalate was synthesized from transesterification of dimethyl oxalate with phenol over TS-1 ( 2.5 wt% Ti ) catalyst. TS-1 catalyst, as a heterogeneous catalyst, showed excellent selectivity of diphenyl oxalat...Diphenyl oxalate was synthesized from transesterification of dimethyl oxalate with phenol over TS-1 ( 2.5 wt% Ti ) catalyst. TS-1 catalyst, as a heterogeneous catalyst, showed excellent selectivity of diphenyl oxalate and methylphenyl oxalate compared with other homogeneous catalysts. Lewis acid sites on TS-1 catalyst were the active sites for transesterification of dimethyl oxalate with phenol. The high selectivity was closely related to the weak acid sites over TS-1.展开更多
One new prenylated flavonol, 7,8-(2'',2'' -dimethylpyrano)-5,3',4'-trihydroxy-3-methoxyflavone was isolated from Hypericum japonicum. The chemical structure was determined by spectroscopic meth...One new prenylated flavonol, 7,8-(2'',2'' -dimethylpyrano)-5,3',4'-trihydroxy-3-methoxyflavone was isolated from Hypericum japonicum. The chemical structure was determined by spectroscopic methods.展开更多
Two new phloroglucinol glycosides, 2,6-dihydroxy-3,5-dimethyl-1-isobutyrylbenzene-4-O-beta-D-glucoside and 2,6-dihydroxy-3,5-dimethyl-1-(2-methylbutyryl) benzene-4-O-beta-D-glucoside were isolated from Hypericum japon...Two new phloroglucinol glycosides, 2,6-dihydroxy-3,5-dimethyl-1-isobutyrylbenzene-4-O-beta-D-glucoside and 2,6-dihydroxy-3,5-dimethyl-1-(2-methylbutyryl) benzene-4-O-beta-D-glucoside were isolated from Hypericum japonicum. Their structures were determined by spectroscopic and chemical methods.展开更多
基金This work was supported by the National Natural Science Foundation of China(20276050)Foundation for University Key Teacher by the Ministry of Educationthe Department of Science and Technology of Yunnan Province for the project on Technology Collaboration and Development in China.
文摘Diphenyl oxalate was synthesized from transesterification of dimethyl oxalate with phenol over TS-1 ( 2.5 wt% Ti ) catalyst. TS-1 catalyst, as a heterogeneous catalyst, showed excellent selectivity of diphenyl oxalate and methylphenyl oxalate compared with other homogeneous catalysts. Lewis acid sites on TS-1 catalyst were the active sites for transesterification of dimethyl oxalate with phenol. The high selectivity was closely related to the weak acid sites over TS-1.
文摘One new prenylated flavonol, 7,8-(2'',2'' -dimethylpyrano)-5,3',4'-trihydroxy-3-methoxyflavone was isolated from Hypericum japonicum. The chemical structure was determined by spectroscopic methods.
文摘Two new phloroglucinol glycosides, 2,6-dihydroxy-3,5-dimethyl-1-isobutyrylbenzene-4-O-beta-D-glucoside and 2,6-dihydroxy-3,5-dimethyl-1-(2-methylbutyryl) benzene-4-O-beta-D-glucoside were isolated from Hypericum japonicum. Their structures were determined by spectroscopic and chemical methods.
