共查询到20条相似文献,搜索用时 218 毫秒
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在鹰爪碱诱导下,2-氯甲基-4,4-二甲基噁唑啉与叔丁基苯基膦硼烷经络合反应,以43%的收率合成了光学纯度大于99%,手性中心在P上的新型手性噁唑啉氮膦配体(3); 3和铱配合物([Ir(cod)Cl]2)经络合反应以55%的收率制得两个新型手性膦噁唑啉铱络合物催化剂(1和2),其结构经1H NMR, 13C NMR, 31P NMR和元素分析表征。考察了1和2对烯烃的不对称氢化反应的催化性能。结果表明:1具有较好的催化能力,收率>92%,但催化剂的手性诱导能力较差(ee≤36%)。 相似文献
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Oligomers of leucine, methionine, phenylalanine, and tyrosine were prepared enzymatically (using papain) from the respective methyl esters, with yields ranging from 51–96%. The effect of pH, buffer and salt concentration, and addition of alcohol on the oligomerization of leucine methyl ester was examined. The limits and potentialities of the enzymatic reaction as a method for obtaining monodisperse oligomers are discussed. 相似文献
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Enantioselective synthesis of optically active α-amino acids from glycine via Schiff base employing (+)-N,N-diisopropyl-10-camphorsulfonamide as a chiral template is described. 相似文献
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以H8-BINOL衍生的手性磷酸硼为催化剂,频哪醇硼烷为还原剂,实现了α-亚氨基酯的不对称还原。经过对反应条件的优化,确定了在0 ℃、反应36 h,催化剂用量5%(以底物的物质的量为基准,下同),3Å分子筛添加量5 mg并以甲苯作为溶剂的条件下,生成的α-氨基酯可达到95%的产率和96%的对映选择性。底物及产物结构均经1H NMR,13C NMR和LC-MS(ESI)表征。该方法中生成的H8-BINOL衍生的手性磷酸硼是一种手性双功能催化剂,该催化剂催化的不对称反应具有条件温和、经济高效和绿色环保的特点。
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以天然氨基酸为手性原料合成了4种新型的手性方酰胺荧光探针分子(5~8), 该合成路线简短, 后处理简单, 无需柱层析纯化. 以荧光光谱为检测手段, 测试了此类探针分子对苯丙氨酸、 缬氨酸和脯氨酸的手性识别效果, 结果表明, 探针分子5可以有效识别苯丙氨酸的2个对映异构体. 当加入L-苯丙氨酸后, 探针分子5的荧光强度显著增强, 而加入D-苯丙氨酸后探针分子5的荧光强度显著减弱, 2种异构体的荧光强度比(IL/ID)可达2.4. 相似文献
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Summary. Secreted peptides from diverse sources have been found to contain a d-amino acid. From the sequence of cloned mRNAs coding for the precursors of such peptides it could be deduced that in all cases tested so far the d-amino acid in the final product is derived from the corresponding l-amino acid present in the primary product of translation. Enzymes catalyzing such an l- to d-isomerization in peptide linkage have been isolated from the venom of a spider and the skin secretions of frogs. Even though
these are completely different proteins, the reaction mechanism is the same, namely a de-protonation/re-protonation of the
α-carbon of an amino acid with concomitant inversion of the chirality. Sequences potentially coding for homologues of the
frog enzyme are present in the genome of different vertebrate species. 相似文献