Ionic liquids （ILs） based on 1,3-dialkylimidazolium and tetraalkylammonium cations were employed as a series of efficient, environmentally benign phase-transfer catalysts （PTCs） for the base-promoted monoalkylatio...Ionic liquids （ILs） based on 1,3-dialkylimidazolium and tetraalkylammonium cations were employed as a series of efficient, environmentally benign phase-transfer catalysts （PTCs） for the base-promoted monoalkylation of diethyl malonate. The influence of various heterogeneous bases on yields was studied. Good yields and high selectivity were obtained. Solvent-free, mild reaction condition, short reaction time, and easy purification were the merits of this method. The catalytic system （IL-hase） could also be recycled after the extraction of products with ether.展开更多
Various 3,4-dihydropyrimidinones can be prepared via Biginelli reaction in aqueous media by using quaternary ammonium salts of different alkyl groups (C4 and C8) and anions (Cl-?and Br-) as catalysts. The use of quate...Various 3,4-dihydropyrimidinones can be prepared via Biginelli reaction in aqueous media by using quaternary ammonium salts of different alkyl groups (C4 and C8) and anions (Cl-?and Br-) as catalysts. The use of quaternary ammonium salts along with longer alkyl chains increases the yield of the Biginelli reaction;however, bromide ammonium salts are less active than the chloride ones.展开更多
An asymmetric fluorinative dearomatization reaction of tryptophol derivatives was developed via chiral anion phase-transfer catalysis. Vari- ous fluorinated furoindolines were obtained in moderate to excellent yields ...An asymmetric fluorinative dearomatization reaction of tryptophol derivatives was developed via chiral anion phase-transfer catalysis. Vari- ous fluorinated furoindolines were obtained in moderate to excellent yields and enantioselectivity in the presence of Selectfluor. The preliminary mecha- nistic studies suggested the existence of an in situ formed tryptophol boronic ester plays a critical role in determining the enantioselectivity. This method features the facile introduction of a fluorine atom in a highly enantioselective manner and construction of two contiguous quaternary stereogenic cen- ters.展开更多
A chloromethylated styrene-divinylbenzene copolymer support system functionalized with 4-benzaldehyde and 2-benzaldehyde was prepared. The degree of functionalization with aldehyde groups is well suited for the subseq...A chloromethylated styrene-divinylbenzene copolymer support system functionalized with 4-benzaldehyde and 2-benzaldehyde was prepared. The degree of functionalization with aldehyde groups is well suited for the subsequent use of the products as Wittig reagents. The polymer bound aldehyde was reacted with Wittig reagents to give olefin groups grafted on styrene-divinylbenzene copolymers. The reactions were carded out in phase transfer catalysis conditions. A simple procedure for the calculation of the degree of functionalization and the statistical modeling of the structural repetitive unit of the copolymer are reported.展开更多
A chiral phase-transfer catalyst,derived from the combination of cinchona alkaloid backbone and BINOL skeleton,enabled a Mannich reaction of glycine Schiff base with N-Boc-imines to generateα,β-diamino acid derivati...A chiral phase-transfer catalyst,derived from the combination of cinchona alkaloid backbone and BINOL skeleton,enabled a Mannich reaction of glycine Schiff base with N-Boc-imines to generateα,β-diamino acid derivatives in excellent yields(up to 99%)and with high diastereo-and enantioselectivities(up to>20∶1 dr,96%ee).展开更多
A facile one-pot, economical approach to 1,2,3-thiadiazol-5-ylureas was developed via seleniumcatalyzed oxidative carbonylation of 1,2,3-thiadiazol-5-amine with a series of amines in one-pot manner in the presence of ...A facile one-pot, economical approach to 1,2,3-thiadiazol-5-ylureas was developed via seleniumcatalyzed oxidative carbonylation of 1,2,3-thiadiazol-5-amine with a series of amines in one-pot manner in the presence of CO and O_2. This approach is featured with cheap and easily available raw materials,cheap and reusable catalyst selenium, one-pot procedure, high atomic economy, simple operations and no emission of corrosive wastes.展开更多
文摘Ionic liquids （ILs） based on 1,3-dialkylimidazolium and tetraalkylammonium cations were employed as a series of efficient, environmentally benign phase-transfer catalysts （PTCs） for the base-promoted monoalkylation of diethyl malonate. The influence of various heterogeneous bases on yields was studied. Good yields and high selectivity were obtained. Solvent-free, mild reaction condition, short reaction time, and easy purification were the merits of this method. The catalytic system （IL-hase） could also be recycled after the extraction of products with ether.
基金financial support of the Ministry of Higher Education and Scientific Research of Tunisia.
文摘Various 3,4-dihydropyrimidinones can be prepared via Biginelli reaction in aqueous media by using quaternary ammonium salts of different alkyl groups (C4 and C8) and anions (Cl-?and Br-) as catalysts. The use of quaternary ammonium salts along with longer alkyl chains increases the yield of the Biginelli reaction;however, bromide ammonium salts are less active than the chloride ones.
文摘An asymmetric fluorinative dearomatization reaction of tryptophol derivatives was developed via chiral anion phase-transfer catalysis. Vari- ous fluorinated furoindolines were obtained in moderate to excellent yields and enantioselectivity in the presence of Selectfluor. The preliminary mecha- nistic studies suggested the existence of an in situ formed tryptophol boronic ester plays a critical role in determining the enantioselectivity. This method features the facile introduction of a fluorine atom in a highly enantioselective manner and construction of two contiguous quaternary stereogenic cen- ters.
文摘A chloromethylated styrene-divinylbenzene copolymer support system functionalized with 4-benzaldehyde and 2-benzaldehyde was prepared. The degree of functionalization with aldehyde groups is well suited for the subsequent use of the products as Wittig reagents. The polymer bound aldehyde was reacted with Wittig reagents to give olefin groups grafted on styrene-divinylbenzene copolymers. The reactions were carded out in phase transfer catalysis conditions. A simple procedure for the calculation of the degree of functionalization and the statistical modeling of the structural repetitive unit of the copolymer are reported.
基金We are grateful for financial support from the National Natural Science Foundation of China(No.21232007).
文摘A chiral phase-transfer catalyst,derived from the combination of cinchona alkaloid backbone and BINOL skeleton,enabled a Mannich reaction of glycine Schiff base with N-Boc-imines to generateα,β-diamino acid derivatives in excellent yields(up to 99%)and with high diastereo-and enantioselectivities(up to>20∶1 dr,96%ee).
基金financial support from the National Natural Science Foundation of China(No.21772033)Program for Innovative Research Team in Science and Technology in University of Henan Province(No. 15IRTSTHN003)
文摘A facile one-pot, economical approach to 1,2,3-thiadiazol-5-ylureas was developed via seleniumcatalyzed oxidative carbonylation of 1,2,3-thiadiazol-5-amine with a series of amines in one-pot manner in the presence of CO and O_2. This approach is featured with cheap and easily available raw materials,cheap and reusable catalyst selenium, one-pot procedure, high atomic economy, simple operations and no emission of corrosive wastes.
