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1.
Highly Regio‐ and Enantioselective Synthesis of N‐Substituted 2‐Pyridones: Iridium‐Catalyzed Intermolecular Asymmetric Allylic Amination 下载免费PDF全文
Xiao Zhang Ze‐Peng Yang Lin Huang Prof. Dr. Shu‐Li You 《Angewandte Chemie (International ed. in English)》2015,54(6):1873-1876
The first iridium‐catalyzed intermolecular asymmetric allylic amination reaction with 2‐hydroxypyridines has been developed, thus providing a highly efficient synthesis of enantioenriched N‐substituted 2‐pyridone derivatives from readily available starting materials. This protocol features a good tolerance of functional groups in both the allylic carbonates and 2‐hydroxypyridines, thereby delivering multifunctionalized heterocyclic products with up to 98 % yield and 99 % ee. 相似文献
2.
Synthesis of Branched Alkylboronates by Copper‐Catalyzed Allylic Substitution Reactions of Allylic Chlorides with 1,1‐Diborylalkanes 下载免费PDF全文
Junghoon Kim Sangwoo Park Jinyoung Park Prof. Dr. Seung Hwan Cho 《Angewandte Chemie (International ed. in English)》2016,55(4):1498-1501
Reported herein is a copper‐catalyzed SN2′‐selective allylic substitution reaction using readily accessible allylic chlorides and 1,1‐diborylalkanes, a reaction which proceeds with chemoselective C?B bond activation of the 1,1‐diborylalkanes. In the presence of a catalytic amount of [Cu(IMes)Cl] [IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazole‐2‐ylidene] and LiOtBu as a base, a range of primary and secondary allylic chlorides undergo the SN2′‐selective allylic substitution reaction to produce branched alkylboronates. The synthetic utilities of the obtained alkylboronates are also presented. 相似文献
3.
Enantioselective Synthesis of Tertiary Allylic Fluorides by Iridium‐Catalyzed Allylic Fluoroalkylation 下载免费PDF全文
Trevor W. Butcher Prof. John F. Hartwig 《Angewandte Chemie (International ed. in English)》2018,57(40):13125-13129
Few allylic electrophiles containing two different substituents at a single allyl terminus and none in which one of the two substituents is a heteroatom, have been shown previously to react with iridium catalysts to form substitution products. We report that iridium‐catalysts are uniquely suited to form tertiary allylic fluorides enantioselectively by the addition of a diverse range of carbon‐centered nucleophiles at the fluorine‐containing terminus of 3‐fluoro‐substituted allylic esters. The products contain tertiary stereogenic centers bearing a single fluorine, which are isosteric with common tertiary stereocenters containing a single hydrogen. Computational studies reveal the principal steric interactions influencing the stability of endo and exo π‐allyl intermediates formed from 3,3‐disubstituted allylic electrophiles. 相似文献
4.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(3):839-844
A highly chemo‐, diastereo‐ and enantioselective catalytic method that efficiently combines a silyl hydride, vinyl‐B(pin) (pin=pinacolato) and (E)‐1,2‐disubstituted allylic phosphates is introduced. Reactions, best promoted by a Cu‐based complex with a chiral sulfonate‐containing N‐heterocyclic carbene, are broadly applicable. Aryl‐, heteroaryl‐, alkenyl‐, alkynyl‐ and alkyl‐substituted allylic phosphates may thus be converted to the corresponding homoallylic boronates and then alcohols (after C−B bond oxidation) in 46–91 % yield and in up to >98 % SN2′:SN2 ratio, 96:4 diastereomeric ratio and 98:2 enantiomeric ratio. The reasons why an NHC−Cu catalyst is uniquely effective (vs. the corresponding phosphine systems) and the basis for different trends in stereoselectivity are provided with the aid of DFT calculations. 相似文献
5.
Dr. J. Caleb Hethcox Samantha E. Shockley Prof. Dr. Brian M. Stoltz 《Angewandte Chemie (International ed. in English)》2016,55(52):16092-16095
The development of the first enantio‐, diastereo‐, and regioselective iridium‐catalyzed allylic alkylation reaction of prochiral enolates to form an all‐carbon quaternary stereogenic center with an aliphatic‐substituted allylic electrophile is disclosed. The reaction proceeds with good to excellent selectivity with a range of substituted tetralone‐derived nucleophiles furnishing products bearing a newly formed vicinal tertiary and all‐carbon quaternary stereodyad. The utility of this protocol is further demonstrated via a number of synthetically diverse product transformations. 相似文献
6.
Samson Afewerki Prof. Dr. Ismail Ibrahem Jonas Rydfjord Palle Breistein Prof. Dr. Armando Córdova 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(10):2972-2977
The first direct intermolecular regiospecific and highly enantioselective α‐allylic alkylation of linear aldehydes by a combination of achiral bench‐stable Pd0 complexes and simple chiral amines as co‐catalysts is disclosed. The co‐catalytic asymmetric chemoselective and regiospecific α‐allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2‐alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2‐alkyl substituted hemiacetals, 2‐alkyl‐butane‐1,4‐diols, and amines. The concise co‐catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed. 相似文献
7.
Catalytic SN2′‐ and Enantioselective Allylic Substitution with a Diborylmethane Reagent and Application in Synthesis 下载免费PDF全文
Ying Shi Prof. Amir H. Hoveyda 《Angewandte Chemie (International ed. in English)》2016,55(10):3455-3458
A catalytic method for the site‐ and enantioselective addition of commercially available di‐B(pin)‐methane to allylic phosphates is introduced (pin=pinacolato). Transformations may be facilitated by an NHC–Cu complex (NHC=N‐heterocyclic carbene) and products obtained in 63–95 % yield, 88:12 to >98:2 SN2′/SN2 selectivity, and 85:15–99:1 enantiomeric ratio. The utility of the approach, entailing the involvement of different catalytic cross‐coupling processes, is highlighted by its application to the formal synthesis of the cytotoxic natural product rhopaloic acid A. 相似文献
8.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(38):12585-12589
The highly chemo‐, enantio‐, and diastereoselective catalyst‐controlled intramolecular allylic C−H insertion and cyclopropanation of donor/donor carbenes are reported. The RuII/Pybox complex selectively catalyzed the intramolecular allylic C−H insertion, providing vinyl‐substituted dihydroindoles with greater than 20:1 chemoselectivity and up to greater than 99 % ee. Chiral dirhodium(II) tetracarboxylates, however, selectively promoted the intramolecular cyclopropanation, giving rise to cyclopropane‐fused tetrahydroquinoline derivatives in excellent yields with greater than 99:1 chemoselectivity and up to 97 % ee. 相似文献
9.
IntroductionWiththefamousDIOPligand ,KaganintroducedtheimportantconceptofC2 symmetryinliganddesign .1However ,itisnotalwaystruethataC2 symmetricligandshouldnecessarilybesuperiortoanon symmetriccoun terpart .Transitionmetal catalyzedallylicalkylationviasymme… 相似文献
10.
Mechanism‐Driven Elaboration of an Enantioselective Bromocyclopropanation Reaction of Allylic Alcohols 下载免费PDF全文
Sylvain Taillemaud Nicolas Diercxsens Prof. Alexandre Gagnon Prof. André B. Charette 《Angewandte Chemie (International ed. in English)》2015,54(47):14108-14112
A stereoselective bromocyclopropanation of allylic alcohols using dibromomethylzinc bromide is described. Spectroscopic studies to monitor the formation of transient intermediates not only led to the development of a more‐atom‐economical halocyclopropanation reaction, but also highlighted the unique role of ether additives in the process. The desired bromo‐substituted cyclopropanes were isolated in high yields and excellent diastereo‐ as well as enantioselectivities using readily available reagents. 相似文献
11.
Xi‐Jia Liu Chao Zheng Yi‐Han Yang Shicheng Jin Shu‐Li You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(31):10603-10609
Described herein is an asymmetric allylic aromatization (AAAr) strategy that employs readily accessible equivalents of benzylic nucleophiles in iridium‐catalyzed allylic substitution reactions with the concomitant formation of aromatic rings by aromatization. The optimized reaction conditions involving a catalyst derived from a commercially available iridium precursor and the Carreira ligand are compatible with equivalents of benzylic nucleophiles derived from 4‐ or 5‐methyloxazoles, 5‐methylthiazoles, 4‐ or 5‐methylfurans, 2‐ or 3‐methylbenzofurans, 3‐methylbenzothiophene, 3‐methylindole, 1‐methylnaphthalene, and methylbenzene. This strategy provides straightforward accesses to valuable heterocyclic aromatic compounds, bearing a homobenzylic stereogenic center, in an enantiopure form and would be difficult to access otherwise. The versatility of the reaction was showcased by the further elaboration of the products into useful building blocks and a drug analogue. 相似文献
12.
Two highly efficient and convenient methods for the synthesis of functionalized and substituted allylic boronates are described. In one procedure, readily available allylic acetates are converted to allylic boronates catalyzed by Ni/PCy(3) or Ni/PPh(3) complexes with high levels of stereoselectivity and in good yields. Alternatively, the borylation can be accomplished with commercially available Pd catalysts [e.g., Pd(2)(dba)(3), PdCl(2), Pd/C], starting with easily accessed allylic halides. 相似文献
13.
Copper‐Catalyzed γ‐Selective and Stereospecific Allylic Cross‐Coupling with Secondary Alkylboranes 下载免费PDF全文
Yuto Yasuda Kazunori Nagao Yoshinori Shido Prof. Dr. Seiji Mori Prof. Dr. Hirohisa Ohmiya Prof. Dr. Masaya Sawamura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9666-9670
The scope of the copper‐catalyzed coupling reactions between organoboron compounds and allylic phosphates is expanded significantly by employing triphenylphosphine as a ligand for copper, allowing the use of secondary alkylboron compounds. The reaction proceeds with complete γ‐E‐selectivity and preferential 1,3‐syn stereoselectivity. The reaction of γ‐silicon‐substituted allylic phosphates affords enantioenriched α‐stereogenic allylsilanes. 相似文献
14.
The enantioselective allylic amination of Morita‐Baylis‐Hillman acetates catalyzed by chiral cyclohexane‐based thiourea‐phosphine catalysts was investigated. In the presence of 20 mol% rosin‐derived thiourea‐phosphine 3j , the chiral amines were obtained in up to 88% yield and up to 85% ee. 相似文献
15.
Olivier Loiseleur MarkC. Elliott Peter vonMatt Andreas Pfaltz 《Helvetica chimica acta》2000,83(9):2287-2294
Chiral, enantiomerically pure Pd‐catalysts were used to control the regioselectivity of nucleophilic attack in allylic substitutions with optically active 1,3‐disubstituted allyl acetates (Schemes 4 – 6). In contrast to reactions with achiral catalysts, where the regioselectivity is determined by the steric and electronic effects of the allylic substituents, chiral catalysts allow selective preparation of either one of the two regioisomeric products, depending on which enantiomer of the catalyst is employed. It is not necessary to start from an enantiomerically pure substrate, because the major and minor enantiomers are converted to different regioisomers (not to enantiomeric products; see Scheme 3), resulting in products of very high ee, even when the starting material is only of moderate enantiomer purity. 相似文献
16.
Metal‐Free Route for the Synthesis of 4‐Acyl‐1,2,3‐Triazoles from Readily Available Building Blocks 下载免费PDF全文
Dr. Joice Thomas Vince Goyvaerts Prof. Dr. Sandra Liekens Prof. Dr. Wim Dehaen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):9966-9970
Functionalized 1,2,3‐triazole heterocycles have been known for a long time and hold an extraordinary potential in diverse research areas ranging from medicinal chemistry to material science. However, the scope of therapeutically important 1‐substituted 4‐acyl‐1H‐1,2,3‐triazoles is much less explored, probably due to the lack of synthetic methodologies of good scope and practicality. Here, we describe a practical and efficient one‐pot multicomponent reaction for the synthesis of α‐ketotriazoles from readily available building blocks such as methyl ketones, N,N‐dimethylformamide dimethyl acetal, and organic azides with 100 % regioselectivity. This reaction is enabled by the in situ formation of an enaminone intermediate followed by its 1,3‐dipolar cycloaddition reaction with an organic azide. We effectively utilized the developed strategy for the derivatization of various heterocycles and natural products, a protocol which is difficult or impossible to realize by other means. 相似文献
17.
(5,6‐Dihydro‐1,4‐dithiin‐2‐yl)methanol as a Versatile Allyl‐Cation Equivalent in (3+2) Cycloaddition Reactions 下载免费PDF全文
Jan Hullaert Prof. Dr. Johan M. Winne 《Angewandte Chemie (International ed. in English)》2016,55(42):13254-13258
The title heterocyclic alcohol readily generates a sulfur‐substituted allylic cation upon simple treatment with a protic acid, thus facilitating a synthetically useful stepwise (3+2) cycloaddition reaction pathway with a range of conjugated‐olefin‐type substrates. The introduction of an allyl fragment in this way provided rapid access to a variety of cyclopentanoid scaffolds. The cyclic nature of the cation precursor alcohol was shown to be instrumental for efficient cycloaddition reactions to take place, thus indicating an attractive strategy for controlling the reactivity of heteroatom‐substituted allyl cations. The formal cycloaddition reaction is highly regio‐ and stereoselective and was also used for a short total synthesis of the natural product cuparene in racemic form through a cycloaddition–hydrodesulfurization sequence. 相似文献
18.
Jian Lei Xiaowu Liu Shaolin Zhang Shuang Jiang Minhao Huang Prof. Dr. Xiaoxing Wu Prof. Dr. Qiang Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6700-6703
An efficient copper‐catalyzed trifluoromethylation of trisubstituted allylic and homoallylic alcohols with Togni’s reagent has been developed. This strategy, accompanied by a double‐bond migration, leads to various branched CF3‐substituted alcohols by using readily available trisubstituted cyclic/acyclic alcohols as substrates. Moreover, for alcohols in which β‐H elimination is prohibited, CF3‐containing oxetanes are isolated as the sole product. 相似文献
19.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(38):11703-11706
The first highly enantioselective iridium‐catalyzed allylic alkylation that provides access to products bearing an allylic all‐carbon quaternary stereogenic center has been developed. The reaction utilizes a masked acyl cyanide (MAC) reagent, which enables the one‐pot preparation of α‐quaternary carboxylic acids, esters, and amides with a high degree of enantioselectivity. The utility of these products is further explored through a series of diverse product transformations. 相似文献
20.
Laura Amens Laura Trulli Luis Nvoa Alejandro Parra Mariola Tortosa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(10):3220-3224
Herein, we report a catalytic and stereospecific method for the preparation of enantioenriched α‐hydroxy cyclopropylboronates with control in four contiguous stereocenters. The reaction involves the borylation of readily available allylic epoxides using an inexpensive Cu(I) salt and a commercially available phosphine ligand. High diastereocontrol is achieved and different diastereomers can be selectively prepared. Functionalization of the carbon–boron bond provides access to different enantiomerically enriched trisubstituted cyclopropanes from a common intermediate. 相似文献