An efficient procedure is reported for the synthesis of 3,3,6,6-tetramethyl-9-aryl-1,8-dioxooctahydroxanthenes using a one-pot condensation of arylaldehydes and 5,5-dimethyl-l,3-cyclohexandione in the presence of DABC...An efficient procedure is reported for the synthesis of 3,3,6,6-tetramethyl-9-aryl-1,8-dioxooctahydroxanthenes using a one-pot condensation of arylaldehydes and 5,5-dimethyl-l,3-cyclohexandione in the presence of DABCO-bromine （TDB） as an acid catalyst. To the best of our knowledge this is the first time that DABCO-bromine is used as an acid catalyst in aqueous media for this type of reaction. This method provides several advantages such as use of water as solvent, easy and clean synthesis, simple work up and versatility.展开更多
Many primary,secondary,tertiary alcohols,and phenolic hydroxyl groups were effectively converted to their corresponding trimethylsilyl ethers using hexamethyldisilazane in the presence of catalytic amounts of tribromo...Many primary,secondary,tertiary alcohols,and phenolic hydroxyl groups were effectively converted to their corresponding trimethylsilyl ethers using hexamethyldisilazane in the presence of catalytic amounts of tribromoisocyanuric acid and DABCO-bromine under mild conditions at room temperature with short reaction times in good to excellent yields.Excellent chemoselective silylation of hydroxyl groups in the presence of other functional groups were also observed.展开更多
The synthesis of C-substituted and N-substituted pyrrole is described by the reaction of phenacyl bromides, pentane-2, 4-dione and amine in aqueous medium using DABCO as a catalyst. The method is very convenient and a...The synthesis of C-substituted and N-substituted pyrrole is described by the reaction of phenacyl bromides, pentane-2, 4-dione and amine in aqueous medium using DABCO as a catalyst. The method is very convenient and applicable for alkyl as well as aryl amines and phenacyl bromides. The procedure is amenable for the synthesis of new substituted pyrroles. Moreover, aqueous medium makes the method more eco-friendly.展开更多
The binding conformations of bidentate ligand DABCO(1,4-diazobicyclo [2,2,2]octane) to a series of p'p type zinc porphyrin dimers covalently linked with flexible alkoxy chain - O(CH2)(n)O- (n=2-10) are described b...The binding conformations of bidentate ligand DABCO(1,4-diazobicyclo [2,2,2]octane) to a series of p'p type zinc porphyrin dimers covalently linked with flexible alkoxy chain - O(CH2)(n)O- (n=2-10) are described by H-1 NMR and UV-vis spectroscopy. DABCO can bind inside the cavities of porphyrin dimers and form a ternary sandwich complex as the alkoxy chain length is long enough. The thermodynamic parameters which control the binding behavior are investigated.展开更多
It has been reported that 1,4-diazabicyclo[2,2,2] octane(DABCO) can form complexed crystals with lithium alkals. Our experimental results show that DABCO can also form cocrystals with phenol derivatives such as phenol...It has been reported that 1,4-diazabicyclo[2,2,2] octane(DABCO) can form complexed crystals with lithium alkals. Our experimental results show that DABCO can also form cocrystals with phenol derivatives such as phenol(2), o-cresol(3), m-cresol(4), p-cresol(5), p-chlorophenol(6), and p-nitrophenol(7). The separa-展开更多
文摘An efficient procedure is reported for the synthesis of 3,3,6,6-tetramethyl-9-aryl-1,8-dioxooctahydroxanthenes using a one-pot condensation of arylaldehydes and 5,5-dimethyl-l,3-cyclohexandione in the presence of DABCO-bromine （TDB） as an acid catalyst. To the best of our knowledge this is the first time that DABCO-bromine is used as an acid catalyst in aqueous media for this type of reaction. This method provides several advantages such as use of water as solvent, easy and clean synthesis, simple work up and versatility.
基金Supported by Bu-Ali Sina University Research Council.
文摘Many primary,secondary,tertiary alcohols,and phenolic hydroxyl groups were effectively converted to their corresponding trimethylsilyl ethers using hexamethyldisilazane in the presence of catalytic amounts of tribromoisocyanuric acid and DABCO-bromine under mild conditions at room temperature with short reaction times in good to excellent yields.Excellent chemoselective silylation of hydroxyl groups in the presence of other functional groups were also observed.
文摘The synthesis of C-substituted and N-substituted pyrrole is described by the reaction of phenacyl bromides, pentane-2, 4-dione and amine in aqueous medium using DABCO as a catalyst. The method is very convenient and applicable for alkyl as well as aryl amines and phenacyl bromides. The procedure is amenable for the synthesis of new substituted pyrroles. Moreover, aqueous medium makes the method more eco-friendly.
基金the National Natural Science Foundation (29871018) and Tianjin Science and Technology Committee Foundation (983602611) of China
文摘The binding conformations of bidentate ligand DABCO(1,4-diazobicyclo [2,2,2]octane) to a series of p'p type zinc porphyrin dimers covalently linked with flexible alkoxy chain - O(CH2)(n)O- (n=2-10) are described by H-1 NMR and UV-vis spectroscopy. DABCO can bind inside the cavities of porphyrin dimers and form a ternary sandwich complex as the alkoxy chain length is long enough. The thermodynamic parameters which control the binding behavior are investigated.
基金Supported by the Excellent Young Teachers' Foundation of the State Education Commission of China
文摘It has been reported that 1,4-diazabicyclo[2,2,2] octane(DABCO) can form complexed crystals with lithium alkals. Our experimental results show that DABCO can also form cocrystals with phenol derivatives such as phenol(2), o-cresol(3), m-cresol(4), p-cresol(5), p-chlorophenol(6), and p-nitrophenol(7). The separa-
