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1.
A novel class of chiral spiro-fused bisoxazoline ligands possessing a deep chiral pocket was prepared.The developed ligands have been employed in the nickel-catalyzed highly enantioselective Michael-type Friedel-Crafts reaction, affording the products bearing a trifluoromethylated all-carbon quaternary stereocenter with moderate to excellent yields(up to 99%) and good to excellent enantioselectivies(up to> 99.9% ee). Moreover, a proposed model of chiral pocket revealed that the attack of indo... 相似文献
2.
The easily prepared and recoverable chiral N-sulfonylated fl-amino alcohol 2 in combination with Ti(OPr-i)4 was found to be an effective chiral catalyst for the enantioselective addition of alkynylzinc to ketones, which gave the useful products, i.e. chiral tertiary propargyl alcohols, with the ee up to 92%. 相似文献
3.
A novel chiral phosphine-triazine ligand was synthesized from chiral α-phenylethylamine through a three-step procedure. In a model reaction of Pd-catalyzed allylic alkylation of rac-1,3-diphenylprop-2-en-1-y1 pivalate with dimethyl malonate, good enantioselectivity (90% e.e.) was obtained by using this ligand. 相似文献
4.
Zheng Hong ZHOU Zhao Ming LI Bing LIU Kang Ying LI Li Xin WANG Guo Feng ZHAO Qi Lin ZHOU Chu Chi TANG 《中国化学快报》2006,17(2):143-146
The asymmetric ring-opening of epoxides with dithiophosphorus acids catalyzed by a (salen)Ti(Ⅳ) complex formed in situ from the reaction of Ti(OPr-i)4 and the chiral Schiff base derived from (1R,2R)-(+)-diaminocyclohexane was realized. The resulting products were obtained with low to good enantioselectivity (up to 73% ee). 相似文献
5.
A complete study of the asymmetric addition of phenylacetylene to ketones catalyzed by Schiff-base amino alcohol-Zn complex is reported in this article. The Schiff-base amino alcohols were easily prepared from amino acids in three steps. When the amount of ligand was 1%(molar fraction), an e.e. value up to 94% was obtained. A series of practical chiral ligands were applied in the enantioselective addition of phenylacetylene to ketones without adding another stronger Lewis acid except zinc. 相似文献
6.
Jia Di Huang~ 《中国化学快报》2008,(3)
A novel chiral phosphine-triazine ligand was synthesized from chiralα-phenylethylamine through a three-step procedure.In a model reaction of Pd-catalyzed allylic alkylation of rac-1,3-diphenylprop-2-en-l-yl pivalate with dimethyl malonate,good enantioselectivity (90% e.e.) was obtained by using this ligand. 相似文献
7.
《中国化学快报》2021,(2)
An unprecedented chiral secondary amine-catalyzed [3+3] annulation of isatin N,N'-cyclic azomethine imines with α,β-unsaturated aldehydes was developed.This strategy allowed the construction of structurally novel spiro N-heterocyclic oxindole derivatives in good yields(up to 91%) and good to excellent enantioselectivities(up to99% ee),albeit with modest diastereoselectivities(up to 3.1:1 dr). 相似文献
8.
N-Arylation of a wide variety of amines with phenylboronic acid catalyzed by copper acetate under 20%aqueous solution of n-Bu4NOH was accomplished in good to excellent yields(up to 92%) and substrate conversions(up to 96%). 相似文献
9.
Geng Xu Zhan Zhu Liu Jing Hua Yang Shi Zhi Chen Hui Ying Yang Institute of Materia Medico Peking Union Medical College & Chinese Academy of Medical Science Beijing China National Institute for the Control of Pharmaceutical Biological Products Beijing China 《中国化学快报》2007,18(6):653-655
Optically active 3-butylphtalide of high enantiomeric excesses (up to 93% e.e.) was synthesized from the reduction of o-pentanoylbenzoic ester with borane using B-methyloxyoxazaborolidine (1b) as the chiral catalyst. 相似文献
10.
《中国科学:化学(英文版)》2021,(8)
A highly enantioselective 1,3-dipolar cycloaddition of α-substituted diazoesters with exocyclic enones was achieved with chiral scandium(III)/N,N′-dioxide complex as the catalyst. This protocol provided a facile and efficient route to optically active 1-pyrazoline-based spirochromanones and others with good outcomes(up to 97% yield, 98% ee with 95:5 dr). Moreover,enantioenriched 2-pyrazoline-based spirochromanones were also accessible by switching α-substituted diazoesters to α-diazoacetates. The further specific transformations of chiral pyrazoline-based spiro-compounds to spirocyclopropane derivatives were disclosed as well. 相似文献
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13.
α,β-Alkynyl ketoesters were introduced to the enantioselective Henry reaction (nitroaldol condensation) with nitromethane catalyzed by tartaric acid derived chiral iminophosphoranes. As such, a variety of optically active β-nitro-substituted tertiary alcohols bearing alkyne moieties were obtained in good to excellent yields (42%-99%) and moderate to good level of enantiomeric excess (up to 87% ee). 相似文献
14.
WANG Rui WEI Zhonglin GUO Jing FENG Yusha XU Enjie DUAN Haifeng LIN Yingjie YANG Qingbiao DU Jianshi LI Yaoxian 《高等学校化学研究》2018,34(2):180-185
Chiral organocatalysts of 4-adamantane amide based on L-proline with double hydrogen potential were synthesized and used in asymmetric aldol reactions. The reactions were evaluated in toluene under -20℃. A series of aldol products was obtained from moderate to good yields(up to 98%) with excellent diastereoselectivities(up to >99:1) and enantioselectivities(up to >99%). The aldol products in the system were separated by α-cyclodextrin via host-guest interaction and determined by chiral HPLC. The catalyst could be reused up to five times. The 4-substitution position played an important role in diastereoselectivity and enantioselectivity. 相似文献
15.
A highly enantioselective 1, 3-dipolar cycloaddition of nitrone with α, β-unsaturated acyl phosphonate was developed for the first time by using a chiral indane-bis(oxazoline)-copper(II) complex. The reaction proceeded smoothly under mild conditions to provide isoxazolidines with multi-stereocenters in good yields with high to excellent diastereo- (>20:1 dr) and enantioselectivities (up to 99% ee). The resulting products were readily converted to multi-functional isoxazolidines or γ-amino alcohol compounds. 相似文献
16.
《Tetrahedron: Asymmetry》2005,16(4):865-868
Some new chiral Schiff bases have been prepared in good yields from various carbonyl groups and two 2-amino alcohols. LiAlH4 was treated with different equivalents of the Schiff bases. Enantioselective reduction of acetophenone is achieved in high chemical yield (up to 93%) with moderate enantiomeric excess (up to 22%) by use of the new reducing agents. 相似文献
17.
Xue-Wei Pu 《Tetrahedron》2010,66(21):3655-6203
A novel class of easily preparative, cheap, and fine-tunable bifunctional chiral tertiary amine-thiourea organocatalysts have been developed by combining both acyclic diamines derived from acyclic α-amino acids and carbohydrates. These organocatalysts promoted the enantioselective conjugate addition of acetylacetone to various nitroolefins in good yields (up to 93%) with good enantioselectivities (up to 91% ee). The present research demonstrates the advantages of incorporating two stereocontrolling structures into a single catalyst. Notably, it offers a simple and convenient doubly stereocontrolled approach for the catalytic asymmetric synthesis of a chiral organic molecule. 相似文献
18.
A synergistic rhodium(Ⅱ)/phosphoric acid catalyzed three component reaction of 3-diazooxindoles,alcohols and N-benzhydryl-α-imino ester is developed for the efficient construction of chiral β-alkoxy C~β-tetrasubstituted α-amino acid derivatives in good yields and with excellent diastereoselectivities and high enantioselectivities.The synthetic application of the resulting products was illustrated by reducing with Pd/C under H_2 atmosphere followed reacting with CSCl_2 at room temperature to rapid afford 3-spirocyclic oxindole in a good yield with a chirality retainment.The three-component reaction is proposed to proceed through an electrophilic trapping of the oxonium ylides by N-benzhydryl-α-imino ester. 相似文献
19.
手性催化剂催化下的不对称合成反应是近年来不对称合成研究中受到重视的领域,如在手性催化剂如,在手性冠醚,手性镧配合物、手性硒、手性铑及手性脯氨酸铷盐等催化下,醛、酮与二烃基锌形成手性醇和不对称羟醛缩合反应等,催化下通过Michael加成反应合成手性化合物的方法近年来也有报道, 相似文献
20.
An enantioselective Strecker synthesis employing novel chiral titanium complex catalysts derived from structurally simple chiral N-salicyl-β-amino alcohols is described. Reactions of N-benzylidenebenzylamine with trimethylsilyl cyanide in the presence of the catalyst (10 mol%) gave the corresponding α-aminonitrile in good to excellent yields, along with relatively high enantioselectivity (up to 86% ee). Similar reactions with various imines derived from aromatic aldehydes resulted in moderate to good enantioselectivity (44-81% ee). 相似文献