共查询到20条相似文献,搜索用时 15 毫秒
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Xiu‐Lan Xie Shou‐Fei Zhu Jun‐Xia Guo Yan Cai Qi‐Lin Zhou 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(11):3022-3025
A palladium‐catalyzed asymmetric O H insertion reaction was developed. Palladium complexes with chiral spiro bisoxazoline ligands promoted the insertion of α‐aryl‐α‐diazoacetates into the O H bond of phenols with high yield and excellent enantioselectivity under mild reaction conditions. This palladium‐catalyzed asymmetric O H insertion reaction provided an efficient and highly enantioselective method for the preparation of synthetically useful optically active α‐aryl‐α‐aryloxyacetates. 相似文献
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β‐ or α,β‐Substituted vinylpyridines react with 3,3‐dimethylbut‐1‐ene in the presence of Wilkinson catalyst [RhCl(PPh3)3] to give the corresponding alkylated products along with unusually isomerized products. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:346–350, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10045 相似文献
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Da Zhao Jiji Zhang Zuowei Xie 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(47):13116-13120
o‐Carboryne can undergo α‐C H bond insertion with tertiary amines, thus affording α‐carboranylated amines in very good regioselectivity and isolated yields. In this process, the nucleophilic addition of tertiary amines to the multiple bond of o‐carboryne generates a zwitterionic intermediate. An intramolecular proton transfer, followed by a nucleophilic attack leads to the formation of the final product. Thus, regioselectivity is highly dependent upon the acidity of α‐C H proton of tertiary amines. This approach serves as an efficient methodology for the preparation of a series of 1‐aminoalkyl‐o‐carboranes. 相似文献
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Benito Alcaide Prof. Dr. Pedro Almendros Dr. Teresa Martínez del Campo Elena Soriano Dr. José L. Marco‐Contelles Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(8):1901-1908
Guiding cyclization : The 5‐exo‐trig cyclization pathway of γ‐allenols can be completely reversed either by changing the metal (Pd instead of Au) or by using a methoxymethyl protecting group, with 7‐endo‐trig alkoxycyclization then dominating instead (see scheme). In addition, the regioselectivity of the La‐catalyzed cycloetherification can be modulated (5‐exo versus 6‐endo versus 7‐endo) simply through subtle variation in the functionalization of the allene component.
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Bin Xu Shou‐Fei Zhu Xiao‐Dong Zuo Zhi‐Chao Zhang Qi‐Lin Zhou 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(15):3994-3997
A highly enantioselective N H insertion reaction of α‐diazoketones was developed by using cooperative catalysis by dirhodium(II) carboxylates and chiral spiro phosphoric acids. The insertion reaction provides a new access route to diverse chiral α‐aminoketones, which are versatile building blocks in organic synthesis, with fast reaction rates, good yields and high enantioselectivity under mild and neutral conditions. 相似文献
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Stacey L. McDonald Charles E. Hendrick Qiu Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(18):4755-4758
Direct amination of heteroarenes and arenes has been achieved in a one‐pot C H zincation/copper‐catalyzed electrophilic amination procedure. This amination method provides an efficient and rapid approach to access a diverse range of heteroaromatic and aromatic amines including those previously inaccessible using C H amination methods. The mild reaction conditions and good functional‐group compatibility demonstrate its great potential for the synthesis of important and complex amines. 相似文献
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Ying‐Ling Chiang Justin A. Russak Nancy Carrillo Jeffrey W. Bode 《Helvetica chimica acta》2012,95(12):2481-2501
A versatile method for the synthesis of enantiomerically pure isoxazolidine monomers for the synthesis of β3‐oligopeptides via α‐keto acid? hydroxylamine (KAHA) ligation is presented. This one‐pot synthetic method utilizes in situ generated nitrones bearing gulose‐derived chiral auxiliaries for the asymmetric 1,3‐dipolar cycloaddition with methyl 2‐methoxyacrylate. The resulting enantiomerically pure isoxazolidine monomers bearing diverse side chains (proteinogenic and non‐proteinogenic) can be synthesized in either configuration (like‐ and unlike‐configured). The scalable and enantioselective synthesis of the isoxazolidine monomers enables the use of the synthesis of β3‐oligopeptides via iterative α‐keto acid? hydroxylamine (KAHA) ligation. 相似文献
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Ken‐ichi Shimizu Dr. Ryosuke Sato Atsushi Satsuma Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(22):3982-3986
Let's drink to that! Two alcohols (one primary and one secondary) can be coupled in an atom‐efficient process by a hydrogen‐autotransfer catalytic system in the form of silver subnanoclusters supported on γ‐Al2O3. The recyclable heterogeneous catalyst promoted the one‐pot C? C cross‐coupling in the presence of a catalytic amount of the weak base Cs2CO3 (see reaction mechanism).
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Hongyin Gao Qing‐Long Xu Muhammed Yousufuddin Daniel H. Ess Lszl Kürti 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(10):2739-2743
We disclose an efficient and operationally simple protocol for the preparation of fused N‐heterocycles starting from readily available 2‐nitrobiaryls and PhMgBr under mild conditions. More than two dozen N‐heterocycles, including two bioactive natural products, have been synthesized using this method. A stepwise electrophilic aromatic cyclization mechanism was proposed by DFT calculations. 相似文献
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Emma L. McInturff Khoa D. Nguyen Michael J. Krische 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(12):3296-3299
Direct ruthenium‐catalyzed C C coupling of alkynes and vicinal diols to form β,γ‐unsaturated ketones occurs with complete levels of regioselectivity and good to complete control over the alkene geometry. Exposure of the reaction products to substoichiometric quantities of p‐toluenesulfonic acid induces cyclodehydration to form tetrasubstituted furans. These alkyne‐diol hydrohydroxyalkylations contribute to a growing body of merged redox‐construction events that bypass the use of premetalated reagents and, hence, stoichiometric quantities of metallic by‐products. 相似文献