共查询到20条相似文献,搜索用时 15 毫秒
1.
Copper‐Catalyzed Reductive Cross‐Coupling of Nonactivated Alkyl Tosylates and Mesylates with Alkyl and Aryl Bromides 下载免费PDF全文
Jing‐Hui Liu Chu‐Ting Yang Xiao‐Yu Lu Zhen‐Qi Zhang Ling Xu Mian Cui Xi Lu Bin Xiao Prof. Dr. Yao Fu Prof. Dr. Lei Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15334-15338
A copper‐catalyzed reductive cross‐coupling reaction of nonactivated alkyl tosylates and mesylates with alkyl and aryl bromides was developed. It provides a practical method for efficient and cost‐effective construction of aryl–alkyl and alkyl–alkyl C?C bonds with stereocontrol from readily available substrates. When used in an intramolecular fashion, the reaction enables convenient access to various substituted carbo‐ or heterocycles, such as 2,3‐dihydrobenzofuran and benzochromene derivatives. 相似文献
2.
Nickel‐Catalyzed Alkyl–Alkyl Cross‐Couplings of Fluorinated Secondary Electrophiles: A General Approach to the Synthesis of Compounds having a Perfluoroalkyl Substituent 下载免费PDF全文
Yufan Liang Prof. Gregory C. Fu 《Angewandte Chemie (International ed. in English)》2015,54(31):9047-9051
Fluorinated organic molecules are of interest in fields ranging from medicinal chemistry to polymer science. Described herein is a mild, convenient, and versatile method for the synthesis of compounds bearing a perfluoroalkyl group attached to a tertiary carbon atom by using an alkyl–alkyl cross‐coupling. A nickel catalyst derived from NiCl2?glyme and a pybox ligand achieves the coupling of a wide range of fluorinated alkyl halides with alkylzinc reagents at room temperature. A broad array of functional groups is compatible with the reaction conditions, and highly selective couplings can be achieved on the basis of differing levels of fluorination. A mechanistic investigation has established that the presence of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) inhibits cross‐coupling under these conditions and that a TEMPO–electrophile adduct can be isolated. 相似文献
3.
Ligand‐Free Copper‐Catalyzed Negishi Coupling of Alkyl‐, Aryl‐, and Alkynylzinc Reagents with Heteroaryl Iodides 下载免费PDF全文
Surendra Thapa Arjun Kafle Dr. Santosh K. Gurung Adam Montoya Patrick Riedel Prof. Ramesh Giri 《Angewandte Chemie (International ed. in English)》2015,54(28):8236-8240
Reported herein is an unprecedented ligand‐free copper‐catalyzed cross‐coupling of alkyl‐, aryl‐, and alkynylzinc reagents with heteroaryl iodides. The reaction proceeds at room temperature for the coupling of primary, secondary, and tertiary alkylzinc reagents with heteroaryl iodides without rearrangement. An elevated temperature (100 °C) is required for aryl–heteroaryl and alkynyl–heteroaryl couplings. 相似文献
4.
Michael P. Crockett Alexander S. Wong Bo Li Jeffery A. Byers 《Angewandte Chemie (International ed. in English)》2020,59(13):5392-5397
Suzuki–Miyaura cross‐coupling reactions between a variety of alkyl halides and unactivated aryl boronic esters using a rationally designed iron‐based catalyst supported by β‐diketiminate ligands are described. High catalyst activity resulted in a broad substrate scope that included tertiary alkyl halides and heteroaromatic boronic esters. Mechanistic experiments revealed that the iron‐based catalyst benefited from the propensity for β‐diketiminate ligands to support low‐coordinate and highly reducing iron amide intermediates, which are very efficient for effecting the transmetalation step required for the Suzuki–Miyaura cross‐coupling reaction. 相似文献
5.
Lucas Montero de Espinosa Kristian Kempe Ulrich S. Schubert Richard Hoogenboom Michael A. R. Meier 《Macromolecular rapid communications》2012,33(23):2023-2028
Olefin cross‐metathesis is introduced as a versatile polymer side‐chain modification technique. The reaction of a poly(2‐oxazoline) featuring terminal double bonds in the side chains with a variety of functional acrylates has been successfully performed in the presence of Hoveyda–Grubbs second‐generation catalyst. Self‐metathesis, which would lead to polymer–polymer coupling, can be avoided by using an excess of the cross‐metathesis partner and a catalyst loading of 5 mol%. The results suggest that bulky acrylates reduce chain–chain coupling due to self‐metathesis. Moreover, different functional groups such as alkyl chains, hydroxyl, and allyl acetate groups, as well as an oligomeric poly(ethylene glycol) and a perfluorinated alkyl chain have been grafted with quantitative conversions. 相似文献
6.
Modular Stereoselective Synthesis of (1→2)‐C‐Glycosides based on the sp2–sp3 Suzuki–Miyaura Reaction 下载免费PDF全文
Beata Oroszova Jan Choutka Dr. Radek Pohl Dr. Kamil Parkan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(19):7043-7047
This work reports a modular and rapid approach to the stereoselective synthesis of a variety of α‐ and β‐(1→2)‐linked C‐disaccharides. The key step is a Ni‐catalyzed cross‐coupling reaction of D ‐glucal pinacol boronate with alkyl halide glycoside easily prepared from commercially available D ‐glucal. The products of this sp2–sp3 cross‐coupling reaction can be converted to glucopyranosyl, mannopyranosyl, or 2‐deoxy‐glucopyranosyl C‐mannopyranosides by one‐ or two‐step stereoselective oxidative–reductive transformations. To the best of our knowledge, we demonstrated the first synthetic application of a challenging sp2–sp3 Suzuki‐Miyaura cross‐coupling reaction in carbohydrate chemistry. 相似文献
7.
Barbier–Negishi Coupling of Secondary Alkyl Bromides with Aryl and Alkenyl Triflates and Nonaflates 下载免费PDF全文
Ke‐Feng Zhang Fadri Christoffel Prof. Dr. Olivier Baudoin 《Angewandte Chemie (International ed. in English)》2018,57(7):1982-1986
A mild and practical Barbier–Negishi coupling of secondary alkyl bromides with aryl and alkenyl triflates and nonaflates has been developed. This challenging reaction was enabled by the use of a very bulky imidazole‐based phosphine ligand, which resulted in good yields as well as good chemo‐ and site selectivities for a broad range of substrates at room temperature and under non‐aqueous conditions. This reaction was extended to primary alkyl bromides by using an analogous pyrazole‐based ligand. 相似文献
8.
Computational Insight into Nickel‐Catalyzed Carbon–Carbon versus Carbon–Boron Coupling Reactions of Primary,Secondary, and Tertiary Alkyl Bromides 下载免费PDF全文
Dr. Man Sing Cheung Fu Kit Sheong Prof. Dr. Todd B. Marder Prof. Dr. Zhenyang Lin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7480-7488
The nickel‐catalyzed alkyl–alkyl cross‐coupling (C?C bond formation) and borylation (C?B bond formation) of unactivated alkyl halides reported in the literature show completely opposite reactivity orders in the reactions of primary, secondary, and tertiary alkyl bromides. The proposed NiI/NiIII catalytic cycles for these two types of bond‐formation reactions were studied computationally by means of DFT calculations at the B3LYP level. These calculations indicate that the rate‐determining step for alkyl–alkyl cross‐coupling is the reductive elimination step, whereas for borylation the rate is determined mainly by the atom‐transfer step. In borylation reactions, the boryl ligand involved has an empty p orbital, which strongly facilitates the reductive elimination step. The inability of unactivated tertiary alkyl halides to undergo alkyl–alkyl cross‐coupling is mainly due to the moderately high reductive elimination barrier. 相似文献
9.
Chuanhu Lei Xiaojia Jin Jianrong Zhou 《Angewandte Chemie (International ed. in English)》2015,54(45):13397-13400
Three‐component couplings were achieved from common aryl halides, alkyl halides, and heteroarenes under palladium and norbornene co‐catalysis. The reaction forges hindered aryl–heteroaryl bonds and introduces ortho‐alkyl groups to aryl rings. Various heterocycles such as oxazoles, thiazoles and thiophenes underwent efficient coupling. The heteroarenes were deprotonated in situ by bases without the assistance of palladium catalysts. 相似文献
10.
The synthesis of 3‐alkyl and arylapomorphines 18–20 has been accomplished by using the Suzuki–Miyaura cross‐coupling reaction of vinyl‐ and allylhalide morphinanedienes or arylhalide apocodeines and arylboronic acids. 相似文献
11.
Prof. Dr. Toshiaki Murai Kenta Morikawa Toshifumi Maruyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(39):13112-13119
The sequential addition of aromatic Grignard reagents to O‐alkyl thioformates proceeded to completion within 30 s to give aryl benzylic sulfanes in good yields. This reaction may begin with the nucleophilic attack of the Grignard reagent onto the carbon atom of the O‐alkyl thioformates, followed by the elimination of ROMgBr to generate aromatic thioaldehydes, which then react with a second molecule of the Grignard reagent at the sulfur atom to form arylsulfanyl benzylic Grignard reagents. To confirm the generation of aromatic thioaldehydes, the reaction between O‐alkyl thioformates and phenyl Grignard reagent was carried out in the presence of cyclopentadiene. As a result, hetero‐Diels–Alder adducts of the thioaldehyde and the diene were formed. The treatment of a mixture of the thioformate and phenyl Grignard reagent with iodine gave 1,2‐bis(phenylsulfanyl)‐1,2‐diphenyl ethane as a product, which indicated the formation of arylsulfanyl benzylic Grignard reagents in the reaction mixture. When electrophiles were added to the Grignard reagents that were generated in situ, four‐component coupling products, that is, O‐alkyl thioformates, two molecules of Grignard reagents, and electrophiles, were obtained in moderate‐to‐good yields. The use of silyl chloride or allylic bromides gave the adducts within 5 min, whereas the reaction with benzylic halides required more than 30 min. The addition to carbonyl compounds was complete within 1 min and the use of lithium bromide as an additive enhanced the yields of the four‐component coupling products. Finally, oxiranes and imines also participated in the coupling reaction. 相似文献
12.
Palladium‐Catalyzed Cross‐Coupling of Unactivated Aryl Sulfides with Arylzinc Reagents under Mild Conditions 下载免费PDF全文
Shinya Otsuka Dr. Daishi Fujino Dr. Kei Murakami Prof. Dr. Hideki Yorimitsu Prof. Dr. Atsuhiro Osuka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13146-13149
Cross‐coupling of general aryl alkyl sulfides with arylzinc reagents proceeds smoothly, even at room temperature or below, with a palladium–N‐heterocyclic carbene (NHC) catalyst. When combined with reactions that are unique to organosulfurs, that is, the SNAr sulfanylation or Pummerer reaction, the cross‐coupling offers interesting transformations that are otherwise difficult to achieve. An alkylsulfanyl group is preferentially converted whilst leaving the tosyloxy and chloro intact, which expands the variety of orthogonal cross‐coupling. 相似文献
13.
A Structure–Activity Study of Nickel NNN Pincer Complexes for Alkyl‐Alkyl Kumada and Suzuki–Miyaura Coupling Reactions 下载免费PDF全文
Thomas Di Franco Marko Stojanovic Sébastien Carlos Keller Rosario Scopelliti Xile Hu 《Helvetica chimica acta》2016,99(11):830-847
A new series of Ni NNN pincer complexes were synthesized and characterized. The main difference among these complexes is the substituents on the side arm amino group(s). No major structural difference was found except for the C–N–C angle of the various substituents and the ‘pseudo bite angle’ of the complexes. Four new complexes were efficient for the alkyl‐alkyl Kumada reaction of primary alkyl halides, and among them, one complex was also efficient with secondary alkyl halides. The influence of the substituents on the catalytic performance of the Ni complexes in alkyl‐alkyl Kumada and Suzuki–Miyaura cross‐coupling reactions was systematically investigated. No correlation was found between the catalytic activity and the key structural parameters (C–N–C angle and ‘pseudo bite angle’), redox properties or Lewis acidity of the complexes. 相似文献
14.
Runze Mao Jonathan Balon Prof. Dr. Xile Hu 《Angewandte Chemie (International ed. in English)》2018,57(41):13624-13628
Alkyl aryl ethers are an important class of compounds in medicinal and agricultural chemistry. Catalytic C(sp3)?O cross‐coupling of alkyl electrophiles with phenols is an unexplored disconnection strategy to the synthesis of alkyl aryl ethers, with the potential to overcome some of the major limitations of existing methods such as C(sp2)?O cross‐coupling and SN2 reactions. Reported here is a tandem photoredox and copper catalysis to achieve decarboxylative C(sp3)?O coupling of alkyl N‐hydroxyphthalimide (NHPI) esters with phenols under mild reaction conditions. This method was used to synthesize a diverse set of alkyl aryl ethers using readily available alkyl carboxylic acids, including many natural products and drug molecules. Complementarity in scope and functional‐group tolerance to existing methods was demonstrated. 相似文献
15.
Catalytic Asymmetric Diels–Alder Reaction of Quinone Imine Ketals: A Site‐Divergent Approach 下载免费PDF全文
Dr. Takuya Hashimoto Hiroki Nakatsu Prof.Dr. Keiji Maruoka 《Angewandte Chemie (International ed. in English)》2015,54(15):4617-4621
The catalytic asymmetric Diels–Alder reaction of quinone imine ketals with diene carbamates catalyzed by axially chiral dicarboxylic acids is reported herein. A variety of primary and secondary alkyl‐substituted quinone derivatives which have not been applied in previous asymmetric quinone Diels–Alder reactions could be employed using this method. More importantly, we succeeded in developing a strategy to divert the reaction site in unsymmetrical 3‐alkyl quinone imine ketals from the inherently favored unsubstituted C?C bond to the disfavored alkyl‐substituted C?C bond. 相似文献
16.
《应用有机金属化学》2017,31(8)
The use of 1,3‐bis(N‐heterocyclic)carbene ligands with different alkyl wingtip groups (alkyl = methyl, isopropyl and tert ‐butyl) is an effective method for the palladium‐catalysed direct S ‐arylation of methylphenyl sulfoxide and C–C coupling of various of aryl halides with alkenes. The reactions proceed in moderate to good yields. Interestingly, it is shown experimentally that, by using bulkier bidentate N‐heterocyclic carbene ligands, more selective catalytic systems towards cis products in Heck coupling reactions can be achieved. 相似文献
17.
Expedient Synthesis of Chiral α‐Amino Acids through Nickel‐Catalyzed Reductive Cross‐Coupling 下载免费PDF全文
Xi Lu Jun Yi Zhen‐Qi Zhang Jian‐Jun Dai Jing‐Hui Liu Prof. Bin Xiao Prof. Yao Fu Prof. Lei Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15339-15343
A novel method for the synthesis of non‐natural L ‐ and D ‐amino acids by a Ni‐catalyzed reductive cross‐coupling reaction is described. This strategy enables the racemization‐free cross‐coupling of serine/homoserine‐ derived iodides with aryl/acyl/alkyl halides. It provides convenient access to varieties of enantiopure and functionalized amino acids, which are important building blocks in bioactive compounds and pharmaceuticals. 相似文献
18.
Dr. Vijay N. Wakchaure Philip S. J. Kaib Markus Leutzsch Prof. Dr. Benjamin List 《Angewandte Chemie (International ed. in English)》2015,54(40):11852-11856
A chiral disulfonimide (DSI)‐catalyzed asymmetric reduction of N‐alkyl imines with Hantzsch esters as a hydrogen source in the presence of Boc2O has been developed. The reaction delivers Boc‐protected N‐alkyl amines with excellent yields and enantioselectivity. The method tolerates a large variety of alkyl amines, thus illustrating potential for a general reductive cross‐coupling of ketones with diverse amines, and it was applied in the synthesis of the pharmaceuticals (S)‐Rivastigmine, NPS R‐568 Hydrochloride, and (R)‐Fendiline. 相似文献
19.
Toshifumi Katagiri Satoshi Ota Takayuki Ohira Takeshi Yamao Shu Hotta 《Journal of heterocyclic chemistry》2007,44(4):853-862
We report the synthesis of various thiophene/phenylene co‐oligomers with a total number of thiophene and benzene (phenylene) rings of 5 and 6 with various terminal groups. Those terminal groups have been chosen from among alkyl groups, methoxy groups, trifluoromethyl groups, and cyano groups. The molecular backbone of these compounds comprises phenyl‐ or biphenylyl‐capped thiophene (or oligothiophene) or an alternating co‐oligomer. The synthesis is based on either the Suzuki coupling reaction or the Negishi coupling reaction. These reaction schemes enabled us to obtain the target compounds in high quality. In particular, the latter coupling method turned out to produce the compounds at a high yield. The terminal groups are expected to produce various functionalities based upon their electron donating character (alkyl groups and methoxy groups) or electron withdrawing character (trifluoromethyl groups and cyano groups). Additionally some of these groups bring about enhanced solubility. This will lead to the production of a diversity of modified compounds of thiophene/phenylene co‐oligomers. To give an example that demonstrates usefulness of the target compounds, we present optoelectronic data that are associated with their device applications. 相似文献
20.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(42):13283-13286
The construction of all C(sp3) quaternary centers has been successfully achieved under Ni‐catalyzed cross‐electrophile coupling of allylic carbonates with unactivated tertiary alkyl halides. For allylic carbonates bearing C1 or C3 substituents, the reaction affords excellent regioselectivity through the addition of alkyl groups to the unsubstituted allylic carbon terminus. The allylic alkylation method also exhibits excellent functional‐group compatibility, and delivers the products with high E selectivity. 相似文献