共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Asymmetric Ruthenium‐Catalyzed Hydrogenation of 2,6‐Disubstituted 1,5‐Naphthyridines: Access to Chiral 1,5‐Diaza‐cis‐Decalins 下载免费PDF全文
Jianwei Zhang Fei Chen Yan‐Mei He Prof. Dr. Qing‐Hua Fan 《Angewandte Chemie (International ed. in English)》2015,54(15):4622-4625
The first asymmetric hydrogenation (AH) of 2,6‐disubstituted and 2,3,6‐trisubstituted 1,5‐naphthyridines, catalyzed by chiral cationic ruthenium diamine complexes, has been developed. A wide range of 1,5‐naphthyridine derivatives were efficiently hydrogenated to give 1,2,3,4‐tetrahydro‐1,5‐naphthyridines with up to 99 % ee and full conversions. This facile and green protocol is applicable to the scaled‐up synthesis of optically pure 1,5‐diaza‐cis‐decalins, which have been used as rigid chelating diamine ligands for asymmetric synthesis. 相似文献
3.
4.
Stefan Westhues Markus Meuresch Prof. Dr. Jürgen Klankermayer 《Angewandte Chemie (International ed. in English)》2016,55(41):12841-12844
Reported is the development of a novel catalytic cascade reaction facilitating the modular synthesis of cyclic tertiary amines from simple lactam substrates and secondary alcohols. Using a single molecular ruthenium‐triphos catalyst in the presence of molecular hydrogen enabled the versatile formation of various amines in high yield with excellent selectivity. Extending the reaction system to using an alcohol as the hydrogen transfer reagent allowed the reduction of lactams without the need for molecular hydrogen. 相似文献
5.
6.
Enzyme‐ and Ruthenium‐Catalyzed Enantioselective Transformation of α‐Allenic Alcohols into 2,3‐Dihydrofurans 下载免费PDF全文
Bin Yang Dr. Can Zhu Dr. Youai Qiu Prof. Dr. Jan‐E. Bäckvall 《Angewandte Chemie (International ed. in English)》2016,55(18):5568-5572
An efficient one‐pot method for the enzyme‐ and ruthenium‐catalyzed enantioselective transformation of α‐allenic alcohols into 2,3‐dihydrofurans has been developed. The method involves an enzymatic kinetic resolution and a subsequent ruthenium‐catalyzed cycloisomerization, which provides 2,3‐dihydrofurans with excellent enantioselectivity (up to >99 % ee). A ruthenium carbene species was proposed as a key intermediate in the cycloisomerization. 相似文献
7.
Dr. James R. Frost Prof. Dr. Stefan M. Huber Dr. Stefan Breitenlechner M. Sc. Christoph Bannwarth Prof. Dr. Thorsten Bach 《Angewandte Chemie (International ed. in English)》2015,54(2):691-695
Spirocyclic oxindoles undergo an enantioselective oxygenation reaction (nine examples; e.r. up to 97:3) upon catalysis by a chiral ruthenium porphyrin complex (1 mol %). The catalyst exhibits a lactam ring, which is responsible for substrate association through hydrogen bonds, and an active ruthenium center, which is in a defined spatial relationship to the oxygenation substrate. DFT calculations illustrate the perfect alignment of the active site with the reactive C? H bond and suggest—in line with the kinetic isotope effect—an oxygen rebound mechanism for the reaction. 相似文献
8.
Dr. Jose R. Cabrero‐Antonino Dr. Iván Sorribes Dr. Kathrin Junge Prof. Dr. Matthias Beller 《Angewandte Chemie (International ed. in English)》2016,55(1):387-391
Reported herein, for the first time, is the selective ruthenium‐catalyzed reductive alkoxylation and amination of phthalimides/succinimides. Notably, this novel methodology avoids hydrogenation of the aromatic ring and allows methoxylation of substituted imides with good to excellent selectivity for one of the carbonyl groups. The reported method opens the door to the development of new processes for the selective synthesis of various functionalized N‐heterocyclic compounds. As an example, intramolecular reductive couplings to afford tricyclic compounds are presented for the first time. 相似文献
9.
Michael T. Bovino Timothy W. Liwosz Nicole E. Kendel Dr. Yan Miller Dr. Nina Tyminska Prof. Eva Zurek Prof. Sherry R. Chemler 《Angewandte Chemie (International ed. in English)》2014,53(25):6383-6387
Chiral saturated oxygen heterocycles are important components of bioactive compounds. Cyclization of alcohols onto pendant alkenes is a direct route to their synthesis, but few catalytic enantioselective methods enabling cyclization onto unactivated alkenes exist. Herein reported is a highly efficient copper‐catalyzed cyclization of γ‐unsaturated pentenols which terminates in C? C bond formation, a net alkene carboetherification. Both intra‐ and intermolecular C? C bond formations are demonstrated, thus yielding functionalized chiral tetrahydrofurans as well as fused‐ring and bridged‐ring oxabicyclic products. Transition‐state calculations support a cis‐oxycupration stereochemistry‐determining step. 相似文献
10.
Ruthenium‐Catalyzed Tandem‐Isomerization/Asymmetric Transfer Hydrogenation of Allylic Alcohols 下载免费PDF全文
Tove Slagbrand Helena Lundberg Prof. Dr. Hans Adolfsson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16102-16106
A one‐pot procedure for the direct conversion of racemic allylic alcohols to enantiomerically enriched saturated alcohols is presented. The tandem‐isomerization/asymmetric transfer hydrogenation process is efficiently catalyzed by [{Ru(p‐cymene)Cl2}2] in combination with the α‐amino acid hydroxyamide ligand 1 , and performed under mild conditions in a mixture of ethanol and THF. The saturated alcohol products are isolated in good to excellent chemical yields and in enantiomeric excess up to 93 %. 相似文献
11.
Nora Thies Dr. Cristian G. Hrib Prof. Dr. Edgar Haak 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(20):6302-6308
Several ruthenium‐catalyzed atom‐economic transformations of propargyl alcohols with pyrroles or indoles leading to alkylated, propargylated, or annulated heteroaromatics are reported. The mechanistically distinct reactions are catalyzed by a single ruthenium(0) complex containing a redox‐coupled dienone ligand. The mode of activation regarding the propargyl alcohols determines the reaction pathway and depends on the alcohols’ substitution pattern. Secondary substrates form alkenyl complexes by a 1,2‐hydrogen shift, whereas the transformation of tertiary substrates involves allenylidene intermediates. 1‐Vinyl propargyl alcohols are converted by a cascade allylation/cyclization sequence. The environmentally benign processes are of broad scope and allow the selective synthesis of highly functionalized pyrroles and indoles generating water as the only waste product. 相似文献
12.
Ying Kit Chung Gregory C. Fu Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(12):2225-2227
Chiral phosphepine 1 catalyzes the transformation of an array of hydroxy‐2‐alkynoates into saturated oxygen heterocycles with good enantioselectivity. Phenols are also shown to participate in such phosphine‐catalyzed cyclizations, including an asymmetric variant. This method provides a new approach to the enantioselective synthesis of tetrahydrofurans, tetrahydropyrans, and dihydrobenzopyrans.
13.
14.
Ruthenium‐Catalyzed Oxidative Kinetic Resolution of Unactivated and Activated Secondary Alcohols with Air as the Hydrogen Acceptor at Room Temperature 下载免费PDF全文
Hirotaka Mizoguchi Dr. Tatsuya Uchida Prof. Tsutomu Katsuki 《Angewandte Chemie (International ed. in English)》2014,53(12):3178-3182
Enantiopure alcohols are versatile building blocks for asymmetric synthesis and the kinetic resolution (KR) of racemic alcohols is a reliable method for preparing them. Although many KR methods have been developed, oxidative kinetic resolution (OKR), in which dioxygen is used as the hydrogen acceptor, is the most atom‐efficient. Dioxygen is ubiquitous in air, which is abundant and safe to handle. Therefore, OKR with air has been intensively investigated and the OKR of benzylic alcohols was recently achieved by using an Ir catalyst without any adjuvant. However, the OKR of unactivated alcohols remains a challenge. An [(aqua)Ru(salen)] catalyzed OKR with air as the hydrogen acceptor was developed, in which the aqua ligand is exchanged with alcohol and the Ru complex undergoes single electron transfer to dioxygen and subsequent alcohol oxidation. This OKR can be applied without any adjuvant to activated and unactivated alcohols with good to high enantioselectivity. The unique influence of substrate inhibition on the enantioselectivity of the OKR is also described. 相似文献
15.
Yusuke Shimada Yoshihiro Miyake Dr. Hiroshi Matsuzawa Dr. Yoshiaki Nishibayashi Prof. Dr. 《化学:亚洲杂志》2007,2(3):393-396
The deracemization of secondary benzylic alcohols proceeds successfully by a two‐step process with the appropriate combination of two different ruthenium complexes for catalysis in the first oxidation and second reduction steps. The sequential catalytic system provides a novel approach to obtaining optically active alcohols, including diols, in high yields with excellent enantioselectivity (up to 95 % ee), in contrast to the conventional kinetic resolution of racemic alcohols. 相似文献
16.
17.
18.
19.
20.
Development of Enantioselective Palladium‐Catalyzed Alkene Carboalkoxylation Reactions for the Synthesis of Tetrahydrofurans 下载免费PDF全文
Brett A. Hopkins Zachary J. Garlets Prof. Dr. John P. Wolfe 《Angewandte Chemie (International ed. in English)》2015,54(45):13390-13392
The Pd‐catalyzed coupling of γ‐hydroxyalkenes with aryl bromides affords enantiomerically enriched 2‐(arylmethyl)tetrahydrofuran derivatives in good yield and up to 96:4 e.r. This transformation was achieved through the development of a new TADDOL/2‐arylcyclohexanol‐derived chiral phosphite ligand. The transformations are effective with an array of different aryl bromides, and can be used for the preparation of products bearing quaternary stereocenters. 相似文献