Tetrahedron, asymmetry最新文献_第4页

Nucleophilic substitution at phosphorus: stereochemistry and mechanisms 磷的亲核取代:立体化学和机理

Tetrahedron, asymmetry Pub Date : 2017-12-15 DOI: 10.1016/j.tetasy.2017.10.022

Oleg I. Kolodiazhnyi, Anastasy Kolodiazhna

引用次数: 37

New functional chiral P-based ligands and application in ruthenium-catalyzed enantioselective transfer hydrogenation of ketones 新型功能性手性p基配体及其在钌催化酮类对映选择性转移加氢中的应用

Tetrahedron, asymmetry Pub Date : 2017-12-15 DOI: 10.1016/j.tetasy.2017.10.004

Nermin Meriç , Cezmi Kayan , Nevin Gürbüz , Mehmet Karakaplan , Nil Ertekin Binbay , Murat Aydemir

{"title":"New functional chiral P-based ligands and application in ruthenium-catalyzed enantioselective transfer hydrogenation of ketones","authors":"Nermin Meriç , Cezmi Kayan , Nevin Gürbüz , Mehmet Karakaplan , Nil Ertekin Binbay , Murat Aydemir","doi":"10.1016/j.tetasy.2017.10.004","DOIUrl":"https://doi.org/10.1016/j.tetasy.2017.10.004","url":null,"abstract":"<div>Metal-catalyzed asymmetric transfer hydrogenation is a powerful and practical method for the reduction of ketones to produce the corresponding secondary alcohols, which are valuable building blocks in the pharmaceutical, perfume, and agrochemical industries. Hence, a series of novel chiral β-amino alcohols were synthesized by chiral amines with regioselective ring opening of (S)-propylene oxide or reaction with (S)-(+)-2-hydroxypropyl p-toluenesulfonate by a straightforward method. The chiral ruthenium catalytic systems generated from [Ru(arene)(μ-Cl)Cl]2 complexes and chiral phosphinite ligands based on amino alcohol derivatives were employed in asymmetric transfer hydrogenation of ketones to give the corresponding optically active alcohols; (2S)-1-{[(2S)-2-[(diphenylphosphanyl)oxy]propyl][(1R)-1-phenylethyl]amino}propan-2-yldiphenylphosphinitobis[dichol-oro(η6-benzene)ruthenium(II)] acts an excellent catalyst in the reduction of α-naphthyl methyl ketone, giving the corresponding alcohol with up to 99% ee. The substituents on the backbone of the ligands were found to have a remarkable effect on both the conversion and enantioselectivity of the catalysts. Furthermore, this transfer hydrogenation is characterized by low reversibility under these conditions.</div>","PeriodicalId":22237,"journal":{"name":"Tetrahedron, asymmetry","volume":"28 12","pages":"Pages 1739-1749"},"PeriodicalIF":0.0,"publicationDate":"2017-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.tetasy.2017.10.004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91631055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Solid supported Hayashi–Jørgensen catalyst as an efficient and recyclable organocatalyst for asymmetric Michael addition reactions 固体负载型Hayashi-Jørgensen催化剂作为不对称Michael加成反应的高效可回收有机催化剂

Tetrahedron, asymmetry Pub Date : 2017-12-15 DOI: 10.1016/j.tetasy.2017.10.016

Piotr Szcześniak , Olga Staszewska-Krajewska , Bartłomiej Furman , Jacek Mlynarski

引用次数: 7

Chiral ethylene-bridged flavinium salts: the stereoselectivity of flavin-10a-hydroperoxide formation and the effect of substitution on the photochemical properties 手性乙烯桥接黄盐:黄素-10a-氢过氧化物形成的立体选择性及取代对光化学性质的影响

Tetrahedron, asymmetry Pub Date : 2017-12-15 DOI: 10.1016/j.tetasy.2017.10.029

Jiří Žurek , Eva Svobodová , Jiří Šturala , Hana Dvořáková , Jiří Svoboda , Radek Cibulka

{"title":"Chiral ethylene-bridged flavinium salts: the stereoselectivity of flavin-10a-hydroperoxide formation and the effect of substitution on the photochemical properties","authors":"Jiří Žurek , Eva Svobodová , Jiří Šturala , Hana Dvořáková , Jiří Svoboda , Radek Cibulka","doi":"10.1016/j.tetasy.2017.10.029","DOIUrl":"https://doi.org/10.1016/j.tetasy.2017.10.029","url":null,"abstract":"<div>A series of chiral non-racemic N1,N10-ethylene bridged flavinium salts 4 was prepared using enantiomerically pure 2-substituted 2-aminoethanols (R = isopropyl, phenyl, benzyl, 4-methoxybenzyl, 4-benzyloxybenzyl) derived from amino acids as the sole source of chirality. The flavinium salts were shown to form 10a-hydroperoxy- and 10a-methoxy-adducts with moderate to high diastereoselectivity depending on the ethylene bridge substituent originating from the starting amino acid. High diastereoselectivities (dr values from 80:20 to >95:5) were observed for flavinium salts bearing benzyl substituents attached to the ethylene bridge. The benzyl group preferred the face-to-face (syn) orientation relative to the flavinium unit; thereby effectively preventing nucleophilic attack from one side. This conformation was found to be the most stable according to the DFT calculations. Consequently, the presence of benzyl groups causes intermolecular fluorescence quenching resulting in a significant decrease in the fluorescence quantum yield from 11% for 4a bearing an isopropyl substituent to 0.3% for 4c containing a benzyl group and to a value lower than 0.1% for the benzyloxybenzyl derivative 4e.</div>","PeriodicalId":22237,"journal":{"name":"Tetrahedron, asymmetry","volume":"28 12","pages":"Pages 1780-1791"},"PeriodicalIF":0.0,"publicationDate":"2017-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.tetasy.2017.10.029","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91631063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Absolute configuration assignment of caffeic acid ester derivatives from Tithonia diversifolia by vibrational circular dichroism: the pitfalls of deuteration 由振动圆二色性的咖啡酸酯衍生物的绝对构型分配:氘化的陷阱

Tetrahedron, asymmetry Pub Date : 2017-12-15 DOI: 10.1016/J.TETASY.2017.10.025

G. V. Ccana-Ccapatinta, B. Sampaio, F. Santos, J. Batista, F. B. Costa

引用次数: 10

Chiral enantiopure organosilane precursors for the synthesis of periodic mesoporous organosilicas 合成周期性介孔有机硅的手性对映纯有机硅烷前驱体

Tetrahedron, asymmetry Pub Date : 2017-12-15 DOI: 10.1016/J.TETASY.2017.10.032

Orit Cohen, R. Abu-Reziq, D. Gelman

引用次数: 4

Stereoselective sulfoxidation catalyzed by achiral Schiff base complexes in the presence of serum albumin in aqueous media 在水介质中血清白蛋白存在下，非手性席夫碱络合物催化立体选择性亚砜化反应

Tetrahedron, asymmetry Pub Date : 2017-12-15 DOI: 10.1016/J.TETASY.2017.10.021

Jie Tang, Peng-fei Yao, Fuping Huang, Meiyi Luo, Yi Wei, Hedong Bian

引用次数: 8

Cumulative author index 累计作者索引

Tetrahedron, asymmetry Pub Date : 2017-12-15 DOI: 10.1016/S0957-4166(17)30540-2

引用次数: 0

O -(α-Phenylethyl)hydroxylamine as a ‘chiral ammonia equivalent’: synthesis and resolution of 5-oxopyrrolidine- and 6-oxopiperidine-3-carboxylic acids 作为“手性氨等价物”的O -(α-苯乙基)羟胺:5-氧吡咯烷和6-氧吡啶-3羧酸的合成和拆分

Tetrahedron, asymmetry Pub Date : 2017-12-15 DOI: 10.1016/J.TETASY.2017.10.027

Ihor Kleban, A. Tymtsunik, Y. Rassukana, O. Grygorenko

引用次数: 3

Absolute configuration assignment of caffeic acid ester derivatives from Tithonia diversifolia by vibrational circular dichroism: the pitfalls of deuteration 由振动圆二色性的咖啡酸酯衍生物的绝对构型分配:氘化的陷阱

Tetrahedron, asymmetry Pub Date : 2017-12-15 DOI: 10.1016/j.tetasy.2017.10.025

Gari V. Ccana-Ccapatinta , Bruno L. Sampaio , Fernando M. dos Santos Jr. , João M. Batista Jr. , Fernando B. Da Costa

{"title":"Absolute configuration assignment of caffeic acid ester derivatives from Tithonia diversifolia by vibrational circular dichroism: the pitfalls of deuteration","authors":"Gari V. Ccana-Ccapatinta , Bruno L. Sampaio , Fernando M. dos Santos Jr. , João M. Batista Jr. , Fernando B. Da Costa","doi":"10.1016/j.tetasy.2017.10.025","DOIUrl":"https://doi.org/10.1016/j.tetasy.2017.10.025","url":null,"abstract":"<div>Recently, it was observed that infrared (IR) and vibrational circular dichroism (VCD) calculations including deuterated hydroxyl groups in phenolic and saccharide moieties improved significantly the agreement with experimental data obtained in methanol-d4. In the present study, the relative and absolute configurations of three methanol-soluble caffeic acid ester derivatives 1–3, isolated from Tithonia diversifolia, were established by a combined use of experimental and calculated 13C NMR chemical shifts, as well as electronic circular dichroism (ECD) and VCD spectroscopies. Interestingly, the attempt to reproduce the deuteration pattern arising from possible isotopic exchange in methanol-d4 solution led to nearly mirror image calculated VCD spectra for 1 when compared to the non-deuterated molecule with the same absolute configuration. This latter fact can potentially lead to absolute configuration misassignments. A closer inspection of the vibrational chiroptical properties of 1 revealed that the deuteration status of the tertiary hydroxyl group at C-2 is critical for the correct reproduction of experimental VCD data in protic solvents. Therefore, in the case of stereochemical analysis of polar chiral natural product molecules, a combination of VCD and ECD is recommended.</div>","PeriodicalId":22237,"journal":{"name":"Tetrahedron, asymmetry","volume":"28 12","pages":"Pages 1823-1828"},"PeriodicalIF":0.0,"publicationDate":"2017-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.tetasy.2017.10.025","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91631060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10