Counteranions of In(III) Induced Reversal of Enantiocontrol in Friedel-Crafts Reaction of Indoles by Asymmetric Binary Acid Catalysis
文献类型：期刊论文
| 作者 | Lu Jian; Qin Yan; Cheng Jinpei; Luo Sanzhong |
| 刊名 | ACTA CHIMICA SINICA
 |
| 出版日期 | 2014-07-15 |
| 卷号 | 72期号:7页码:809-814 |
| 关键词 | Asymmetric Catalysis Friedel-crafts Alkylation Switchable Enantioselectivity Binary-acid Counter Anion Effect |
| ISSN号 | 0567-7351 |
| DOI | 10.6023/A14040246 |
| 英文摘要 | Effective access to both enantiomers of any targeted products from a single chiral source of catalyst is highly desirable in asymmetric catalysis. Such dual stereocontrol has normally been encountered with structural modifications on the chiral ligands or catalysts skeletons. Recently, simple variations of reactions conditions such as solvents, temperature, additive and catalytic metal center, can lead to remarkable reversal of enantioselectivity with minimum structural modifications, thus providing a modular and synthetic appealing approach in asymmetric catalysis and synthesis. Previously, we have developed asymmetric binary acid catalysis wherein chiral Bronsted acids, mostly phosphoric acids, are utilized as dual acids and ligands in concert with metal catalysts, and this type of catalysis demonstrated tunable, even switchable stereoselectivity due to the combinatorial and synergistic features. In particular, simple swap of counteranion (from F- to Br-) of Indium(III) salts led to complete switch of regioselectivity (1,2- vs. 1,4-addition) in the reaction of N-methyl indole 2a' and ketoester 3a with high enantioselectivity achieved for both regioisomers. In our further studies, we have found that when indole 2a was employed instead of N-methyl indole 2a', the counter anion effect on regioselectivity was not observed and both InF3 and InBr3 promoted exclusively 1,4-addition reactions. Interestingly, reversal of enantioselectivity of the 1,4-conjugate adduct was observed by simple swap of counter anions of indium(III). The obtained optimal binary-acids combination, InF3(1c)(2) and InBr3(1d)(2) were found to be R- and S-selective catalyst for the 1,4-addition reactions, respectively. In the presence of asymmetric binary-acid catalysts (InX3/1, 2.5 mol%), indoles and beta,gamma-unsaturated alpha-ketoesters were stirred at -70 degrees C for 24 h to afford the various indole esters 4 in good to excellent yield (up to 98% yield) and enantioselectivities (up to >99% ee). |
| 语种 | 英语 |
| WOS记录号 | WOS:000340842000006 |
| 出版者 | SCIENCE PRESS |
| 源URL | [http://ir.iccas.ac.cn/handle/121111/51549]  |
| 专题 | 中国科学院化学研究所 |
| 通讯作者 | Lu Jian |
| 作者单位 | Chinese Acad Sci, Inst Chem, CAS Key Lab Mol Recognit & Funct, BNLMS, Beijing 100190, Peoples R China |
| 推荐引用方式 GB/T 7714 | Lu Jian,Qin Yan,Cheng Jinpei,et al. Counteranions of In(III) Induced Reversal of Enantiocontrol in Friedel-Crafts Reaction of Indoles by Asymmetric Binary Acid Catalysis[J]. ACTA CHIMICA SINICA,2014,72(7):809-814. |
| APA | Lu Jian,Qin Yan,Cheng Jinpei,&Luo Sanzhong.(2014).Counteranions of In(III) Induced Reversal of Enantiocontrol in Friedel-Crafts Reaction of Indoles by Asymmetric Binary Acid Catalysis.ACTA CHIMICA SINICA,72(7),809-814. |
| MLA | Lu Jian,et al."Counteranions of In(III) Induced Reversal of Enantiocontrol in Friedel-Crafts Reaction of Indoles by Asymmetric Binary Acid Catalysis".ACTA CHIMICA SINICA 72.7(2014):809-814. |
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来源：化学研究所
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