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采用以L-脯氨酸为原料合成的5种手性β-氨基醇作为有机小分子催化剂,用于催化α,β-不饱和酮的不对称环氧化反应。考察了影响对映选择性的催化剂结构、氧化剂种类、溶剂、反应温度等因素。结果表明,催化剂的结构、氧化剂的种类、反应的溶剂对对映选择性和化学产率影响较大,而反应温度在室温至-20℃范围内,对反应的对映选择性和化学产率影响不明显。当以叔丁基过氧化氢(TBHP)为氧化剂、正己烷为溶剂、在室温下、以(S)-2-吡咯烷-α,α-二(α-萘基)甲醇(2b)作催化剂时,所得环氧化物的对映体过量最高为84.6%e.e.,产率最高为89.7%。通过1H NMR对所得环氧化物4的结构进行了表征,并利用手性色谱柱通过高效液相色谱法(HPLC)对产物4的对映体过量进行了测定。 相似文献
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以天然手性产物L-脯氨酸为原料,经酯化、氨基保护和格氏反应,得到一种新型光学活性的脯氨醇衍生物((S)-N-苄基-2-吡咯烷-α,α-二(α-萘基)甲醇1).1经过催化氢解,得到另一种光学活性脯氨醇衍生物((S)-2-吡咯烷-α,α-二(α-萘基)甲醇2).将1和2作为有机催化剂,用于催化二烷基锌和醛的不对称加成反应.分别考察了影响对映选择性的催化剂结构、催化剂用量、溶剂、反应温度等各种因素.结果表明,当催化剂用量为5%、溶剂为甲苯、反应温度为-10℃,1作催化剂时,所得仲醇的对映体过量达82?,产率高达100%. 相似文献
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以四丁基碘化铵(TBAI)为相转移催化剂,催化(1-重氮基-2-氧代丙基)膦酸二甲酯(Ohira-Bestmann试剂)与芳香醛衍生的α-氨基砜的Mannich反应.通过对反应条件进行筛选,确定了-40℃下,以甲苯为反应溶剂和质量分数为10%的Li OH溶液为碱的最佳反应条件.通过底物的扩展,合成了一系列β-氨基膦酸酯衍生物,收率为52%~93%,所得产物结构经核磁共振谱(NMR)和质谱(MS)表征.通过Ohira-Bestmann试剂与α-氨基砜的Mannich反应,提供了一条有效制备β-氨基膦酸酯衍生物的方法. 相似文献
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对七水合三氯化铈-碘化钠(CeCl3·7H2O-NaI)化邻氨基苯硫酚、对氯邻氨基苯硫酚、间氨基苯硫酚、对氨基苯硫酚和对甲基苯硫酚与α,β-不饱和酮(1a~1o)的迈克尔加成反应进行了系统研究.结果表明,CeCl3·7H2O-NaI-SiO2复合催化剂能有效催化邻氨基苯硫酚及对氯邻氨基苯硫酚与α,β-不饱和酮(1a~1o)的迈克尔加成反应.在优化的反应条件下,即n(CeCl3·7H2O)∶n(NaI)∶n(α,β-不饱和酮)=1∶2∶2,m(CeCl3·7H2O)∶m(SiO2)=1∶1.6,三氯甲烷作溶剂,反应温度为回流温度,反应时间为2 h,反应可达到中等产率(43.1%~58.8%).催化剂重复使用4次基本稳定.此外,提出了可能的催化机理. 相似文献
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《Tetrahedron: Asymmetry》2007,18(6):734-741
A new series of amino alcohols with a chiral cyclopropane backbone have been developed and used in the catalytic asymmetric diethylzinc addition and phenyl transfer to various types of aldehydes. These cyclopropane-based chiral amino alcohols show high enantioselectivity in the addition of organozincs to aromatic and aliphatic aldehydes. For diethylzinc addition to aromatic and aliphatic aldehydes, up to 97% ee and 93% ee are obtained, respectively. For the phenyl transfer to aromatic aldehydes, the best enantioselectivity was 89% ee. 相似文献
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Alakesh Bisai 《Tetrahedron》2007,63(3):598-601
Titanium(IV) complexes of bidentate trans-cyclohexane 1,2-diamine-based unsymmetrical chiral bis(sulfonamide) ligands were evaluated as catalysts for the asymmetric addition of diethylzinc to aldehydes. The reaction provided secondary alcohols in quantitative yields and very good enantioselectivity (up to 96% ee). 相似文献
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Kavita Pathak Irshad Ahmad Sayed H.R. Abdi Rukhsana I. Kureshy Noor-ul H. Khan Raksh V. Jasra 《Journal of molecular catalysis. A, Chemical》2008,280(1-2):106-114
Chiral BINOL was covalently anchored on two different pore sized mesoporous silica (SBA-15 (7.5 nm) and MCF (14 nm)). These heterogenized ligands were used in Ti-catalyzed asymmetric addition of diethylzinc to aldehydes. High catalytic activity with excellent enantioselectivity (up to 94% ee) for secondary alcohols was achieved using MCF supported chiral BINOL under heterogeneous reaction conditions. Good to excellent enantioselectivity (ee, 68–91%) was also achieved with various small to bulkier aldehydes. The MCF supported catalyst was reused in multiple catalytic runs without loss of enantioselectivity. 相似文献
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A set of secondary N-phenylfluorenyl beta-amino alcohols have been prepared and evaluated as catalysts for the enantioselective addition of diethylzinc to benzaldehyde. The influence of the substituents on the stereogenic centers of the ligand has been studied, and enantioselectivities up to 97% have been obtained. Those ligands with bulky groups in the carbinol stereocenter and small groups alpha to the nitrogen atom displayed the best catalytic activity and enantioselectivity. The most enantioselective ligand (4e) was found to possess general applicability for the enantioselective addition of diethylzinc to a variety of aromatic and aliphatic aldehydes. 相似文献
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[reaction: see text] A set of 2-dialkylaminomethyl-2'-hydroxy-1,1'-binaphthyls was prepared and used in the catalytic asymmetric additions of diethylzinc and diphenylzinc to various types of aldehydes. These binaphthyl-based axially chiral amino alcohols show high enantioselectivity in the addition of organozincs to aromatic and aliphatic aldehydes. 相似文献
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Synthesis of chiral ferrocenyl aziridino alcohols and use in the catalytic asymmetric addition of diethylzinc to aldehydes 总被引:1,自引:0,他引:1
Min-Can Wang Lan-Tao Liu Jun-Song Zhang Yan-Yan Shi De-Kun Wang 《Tetrahedron: Asymmetry》2004,15(24):3853-3859
A series of novel chiral ferrocenyl aziridino alcohols 5a–i were conveniently synthesized from L-serine and ferrocenecarboxaldehyde. These compounds have been used as chiral catalysts in the asymmetric addition of diethylzinc to aldehydes and the effects of the ligand structures on the enantioselectivity was studied. Enantioselectivities up to 98.8% have been obtained. 相似文献
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Szymon Jarzyński Greta Utecht Stanisław Leśniak Michał Rachwalski 《Tetrahedron: Asymmetry》2017,28(12):1774-1779
Enantiomerically pure, chiral secondary and tertiary aziridine alcohols (including the aziridine analogue of ProPhenol—AziPhenol) have proven to be highly effective catalysts for enantioselective asymmetric reactions in the presence of zinc ions, including arylation of aromatic aldehydes, epoxidation of chalcone and addition of diethylzinc to aldehydes, leading to the desired chiral products in high chemical yields (up to 90%) and with ee’s up to 90%. A higher catalytic activity of Prophenol-type bis(aziridine alcohol) in the aforementioned asymmetric transformations has been demonstrated. 相似文献