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(S)-(1-Benzylpyrrolidin-2-yl)diphenylmethanol and cinchonine were evaluated as promotors in the asymmetricadditions of phenylacetylene to ketones,in order to prepare chiral propargylic alcohols.Good yields(up to 89%)and moderate enantioselectivities(up to 77.9% ee)were achieved.Addition of Ti(OPr-i)_4 can significantly improvethe enantioselectivity of the reaction. 相似文献
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新型双官能团有机小分子催化剂的设计合成 总被引:1,自引:0,他引:1
基于天然L-氨基酸的基本结构,设计了一系列双官能团的有机小分子催化剂,并以天然氨基酸为起始原料,经过多步反应合成了这些目标化合物,产物结构经核磁分析正确. 相似文献
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The substituent effects in the Birch reduction reaction of substituted benzenes are discussed. A nonplanar^boat-form conformation is suggested for the benzene radical union formed by the transfer of an electron to a substituted benzene-molecule. In this conformation the 1,4 -dienyl radical union has two double bonds isolated,the negative charge is localized on po-sion 6 and the. single electron is on position 3.the farthest position from the negative charge, when the substituent is electron-withdrawing. Both alkyl and alkoxy groups are considered to be electron-withdrawing. These sub-stituents should be activating groups for their inductive effect. The reaction rate decreasing of alkyl benzenes may be caused by reasons other than electronic effect. The reduction of benzole acid and. benzamide, in which 1,4-dihydro benzenes are obtained,is considered to be an exceptional example,in which an extra stabilized Y-aromatic radical union may be involved. 相似文献
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标题化合物8-一种新的手性催化剂,通过丙二酸酯法及酶解拆分合成(s)-3-(2-氯苯基)丙氨酸甲酯,进一步与溴苯发生格氏反应而成。 相似文献
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通过膦酸酯与草酸酯的缩合,合成了一系列新的3-芳基-3-(二烷氧基膦酰)丙酮酸酯,并对其结构进行了表征,该类化合物以酮式-烯醇式平衡混合物形式存在. 相似文献
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