The enantioselective cycloetherification of substituted keto phenols into their corresponding dihydrobenzofuran derivatives was carried out using hydrogen peroxide and chiral quaternary ammonium iodide in micellar med...The enantioselective cycloetherification of substituted keto phenols into their corresponding dihydrobenzofuran derivatives was carried out using hydrogen peroxide and chiral quaternary ammonium iodide in micellar media. This approach increased the conversion rate of cycloetherification and also widened the scope of this particular reaction for various substituted keto phenols with electron withdrawing as well as electron donating functionalities. The use of a surfactant in the cycloetherification reaction increased the yield of the corresponding enantioselective dihydrobenzofuran four times. The conversion rate of keto phenols into their corresponding dihydrobenzofuran derivatives was proportional to the concentration of the surfactant used in the reaction.展开更多
Water soluble polyether phosphites alkyl polyethylene glycol o phenylene phosphite (APGPPs) were easily prepared via alcoholysis of phosphorus chloride with polyoxyethylene alkyl ether. With appropriate HLB (hy...Water soluble polyether phosphites alkyl polyethylene glycol o phenylene phosphite (APGPPs) were easily prepared via alcoholysis of phosphorus chloride with polyoxyethylene alkyl ether. With appropriate HLB (hydrophile lypophile balance), the phosphites possess clear cloud points below 100 ℃. Addition of some inorganic salts decreases cloud points of the phosphites. When the phosphites have long polyether chain binding to short chain alkyl group, their cloud points could be extrapolated from figure of dependence of cloud points on addition of inorganic salts. Utilizing octylpolyglycol phenylene phosphite (OPGPP) (APGPP, R: Octyl)/Rh complex formed in situ as catalyst, over 90% conversion of 1 decene was obtained, avoiding the limitation of water insolubility of substrates. Preliminary results indicated that micellar catalysis and thermoregulated phase transfer catalysis (TRPTC) coexist in the reaction system. Below cloud point, micellar catalysis induced by polyether phosphites may be existed. When temperature is increased to above cloud point of the phosphites, this reaction works mainly in TRPTC. The catalysts could be easily separated by simple decantation, but followed by considerable loss in activity after three successive reaction runs. Preliminary results indicated hydrolysis of OPGPP happened during the reaction, which may explain for the bad loss in activity. The catalyst was reused up to seven times without clear decrease in activity when OPGPP/Rh ratio was increased to 50.展开更多
基金Supported by the Rhodes University Joint Research Committee (JRC,grant number 35047)
文摘The enantioselective cycloetherification of substituted keto phenols into their corresponding dihydrobenzofuran derivatives was carried out using hydrogen peroxide and chiral quaternary ammonium iodide in micellar media. This approach increased the conversion rate of cycloetherification and also widened the scope of this particular reaction for various substituted keto phenols with electron withdrawing as well as electron donating functionalities. The use of a surfactant in the cycloetherification reaction increased the yield of the corresponding enantioselective dihydrobenzofuran four times. The conversion rate of keto phenols into their corresponding dihydrobenzofuran derivatives was proportional to the concentration of the surfactant used in the reaction.
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .2 990 60 0 1)
文摘Water soluble polyether phosphites alkyl polyethylene glycol o phenylene phosphite (APGPPs) were easily prepared via alcoholysis of phosphorus chloride with polyoxyethylene alkyl ether. With appropriate HLB (hydrophile lypophile balance), the phosphites possess clear cloud points below 100 ℃. Addition of some inorganic salts decreases cloud points of the phosphites. When the phosphites have long polyether chain binding to short chain alkyl group, their cloud points could be extrapolated from figure of dependence of cloud points on addition of inorganic salts. Utilizing octylpolyglycol phenylene phosphite (OPGPP) (APGPP, R: Octyl)/Rh complex formed in situ as catalyst, over 90% conversion of 1 decene was obtained, avoiding the limitation of water insolubility of substrates. Preliminary results indicated that micellar catalysis and thermoregulated phase transfer catalysis (TRPTC) coexist in the reaction system. Below cloud point, micellar catalysis induced by polyether phosphites may be existed. When temperature is increased to above cloud point of the phosphites, this reaction works mainly in TRPTC. The catalysts could be easily separated by simple decantation, but followed by considerable loss in activity after three successive reaction runs. Preliminary results indicated hydrolysis of OPGPP happened during the reaction, which may explain for the bad loss in activity. The catalyst was reused up to seven times without clear decrease in activity when OPGPP/Rh ratio was increased to 50.
