共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
A convenient preparation of racemic 2-substituted 9,10-anthraquinones that included 2-triazoylethyl skeleton 1 and 2-alkylethyl skeleton 6 is reported. The products were obtained in good yields by a three- or four-step synthetic route based on a sequence of N-bromosuccinimide (NBS)–mediated bromination of 2-ethyl-9,10-anthraquinone 2, nucleophilic substitution, and CuI-catalyzed 1,3-dipolar cycloaddition or alkylation/reductive desulfonylation. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
3.
The exciting chemistry of tetraazidomethane 总被引:2,自引:0,他引:2
Banert K Joo YH Rüffer T Walfort B Lang H 《Angewandte Chemie (International ed. in English)》2007,46(7):1168-1171
4.
5.
Vallée MR Majkut P Wilkening I Weise C Müller G Hackenberger CP 《Organic letters》2011,13(20):5440-5443
Site-specific functionalization of proteins by bioorthogonal modification offers a convenient pathway to create, modify, and study biologically active biopolymers. In this paper the Staudinger reaction of aryl-phosphonites for the chemoselective functionalization of azido-peptides and proteins was probed. Different water-soluble phosphonites with oligoethylene substituents were synthesized and reacted with unprotected azido-containing peptides in aqueous systems at room temperature in high conversions. Finally, the Staudinger-phosphonite reaction was successfully applied to the site-specific modification of the protein calmodulin. 相似文献
6.
Direct Trifluoromethylthiolation of Alcohols under Mild Reaction Conditions: Conversion of ROH into RSCF3 下载免费PDF全文
Pavlo Nikolaienko Roman Pluta Prof. Dr. Magnus Rueping 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9867-9870
A direct process for the trifluoromethylthiolation of allylic and benzylic alcohols under mild conditions has been developed. A wide range of free alcohols underwent nucleophilic substitution in the presence of stable CuSCF3 and BF3 ? Et2O to give the corresponding products in good to excellent yields. 相似文献
7.
Shu-Su Shen 《Tetrahedron letters》2009,50(26):3161-1471
The nucleophilic substitution reactions of vinylic bromides with intramolecular thioamide or thiourea moieties proceed to give a series of substituted thiazoles and imidazole-2-thiones. 相似文献
8.
在B3LYP/6-311 G(2df,p)的水平上,对反应X- CH3SCl(X=F,Cl,Br,I)进行了理论研究.计算结果表明:X-(X=Cl,Br,I)与CH3SCl作用时,实际发生的是在硫原子上而不是在碳原子上的亲核取代反应,而且属于加成-消去机理.但是F-与CH3SCl作用则容易发生脱质子反应. 相似文献
9.
Furuyama T Yonehara M Arimoto S Kobayashi M Matsumoto Y Uchiyama M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(33):10348-10356
We present full details of the unique reactivities of the newly developed dianion-type bulky zincate, dilithium tetra-tert-butylzincate (tBu(4)ZnLi(2)). With this reagent, halogen-zinc exchange reaction of variously functionalized haloaromatics and anionic polymerization of N-isopropylacrylamide (NIPAm)/styrene with excellent chemoselectivity were realized. Halogen-zinc exchange reaction followed by electrophilic trapping with propargyl bromide provided a convenient route to functionalized phenylallenes, particularly those with electrophilic functional groups (such as cyano, amide and halogens). Spectral and computational studies of the structure in the gas and liquid phases indicated extraordinary stabilization of this dianion-type zincate by its bulky ligands. 相似文献
10.
Ring Opening of Donor–Acceptor Cyclopropanes with the Azide Ion: A Tool for Construction of N‐Heterocycles 下载免费PDF全文
Konstantin L. Ivanov Dr. Elena V. Villemson Dr. Ekaterina M. Budynina Dr. Olga A. Ivanova Dr. Igor V. Trushkov Prof. Mikhail Ya. Melnikov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):4975-4987
A general method for ring opening of various donor–acceptor cyclopropanes with the azide ion through an SN2‐like reaction has been developed. This highly regioselective and stereospecific process proceeds through nucleophilic attack on the more‐substituted C2 atom of a cyclopropane with complete inversion of configuration at this center. Results of DFT calculations support the SN2 mechanism and demonstrate good qualitative correlation between the relative experimental reactivity of cyclopropanes and the calculated energy barriers. The reaction provides a straightforward approach to a variety of polyfunctional azides in up to 91 % yield. The high synthetic utility of these azides and the possibilities of their involvement in diversity‐oriented synthesis were demonstrated by the developed multipath strategy of their transformations into five‐, six‐, and seven‐membered N‐heterocycles, as well as complex annulated compounds, including natural products and medicines such as (?)‐nicotine and atorvastatin. 相似文献
11.
Cover Picture: Ring Opening of Donor–Acceptor Cyclopropanes with the Azide Ion: A Tool for Construction of N‐Heterocycles (Chem. Eur. J. 13/2015) 下载免费PDF全文
Konstantin L. Ivanov Dr. Elena V. Villemson Dr. Ekaterina M. Budynina Dr. Olga A. Ivanova Dr. Igor V. Trushkov Prof. Mikhail Ya. Melnikov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):4857-4857
12.
Gonzalo Jiménez‐Osés Dr. Alberto Avenoza Dr. Jesús H. Busto Dr. Fernando Rodríguez Dr. Jesús M. Peregrina Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(38):9810-9823
Cyclic hindered sulfamidates exhibited an outstanding performance in their ring‐opening reactions with alcohols and in the absence of any external activator. The mechanism of this unprecedented transformation was thoroughly studied both experimentally and theoretically. As a result, a nontrivial stepwise pathway involving solvent‐induced conversion of the sulfamidates to activated aziridinium and then to oxazolinium cations, which are finally opened at their 5‐position with inversion of configuration, is proposed. The presence of the SO3 moiety in the sulfamidate was revealed as a “built‐in activator”. In fact, the spontaneous SO3 cleavage takes place under the reaction conditions and avoids the subsequent step of hydrolysis after the ring opening of the sulfamidates. This is another important improvement of this methodology with respect to the standard basic conditions, allowing a greater compatibility with other functional groups. Furthermore, the carbamate group plays a key role in this mechanism. Briefly, a highly chemoselective and stereoespecific formal solvolysis of hindered sulfamidates with alcohols without further activation is described. This reaction takes place exclusively at the quaternary center with inversion of configuration, providing a new straightforward synthetic route to O‐substituted α‐methylisoserines. 相似文献
13.
Stereoselective Synthesis and Reactions of Secondary Alkyllithium Reagents Functionalized at the 3‐Position 下载免费PDF全文
Kohei Moriya Dr. Dorian Didier Meike Simon Jeffrey M. Hammann Dr. Guillaume Berionni Prof. Dr. Konstantin Karaghiosoff Prof. Hendrik Zipse Prof. Dr. Herbert Mayr Prof. Dr. Paul Knochel 《Angewandte Chemie (International ed. in English)》2015,54(9):2754-2757
Secondary alkyllithium reagents bearing an OTBS group (TBS=tert‐butyldimethylsilyl) at the 3‐position can be prepared stereoconvergently through an I/Li exchange from a diastereomeric mixture of the corresponding secondary alkyl iodides. These lithium reagents react with a range of electrophiles, including carbon electrophiles, with retention of configuration to yield various 1,3‐difunctionalized derivatives with good diastereoselectivities. Kinetic studies show that the 3‐siloxy group strongly accelerates the epimerization at the lithium‐substituted carbon atom. This method offers a new way to construct chiral open‐chain molecules with excellent stereoselectivity. 相似文献
14.
T. N. Solomoichenko Yu. S. Sadovskii T. M. Prokop’eva E. A. Karpichev I. V. Kapitanov Zh. P. Piskunova V. A. Savelova A. F. Popov 《Theoretical and Experimental Chemistry》2006,42(6):364-370
We have studied the nucleophilicity of the hydroperoxide anion relative to 4-nitrophenyl diethyl phosphonate (NPDEPS) in the
presence of cetyltrimethylammonium bromide (water, 25 °C) while varying the acidity of the medium and the hydroperoxide anion
concentration over a broad range. The increase in the reaction rate when the reaction is transferred to a micellar pseudophase
is as high as ∼10-fold, which is explained by concentration effects. In CTAB micelles, as in water, the hydroperoxide ion
is one of the most effective α-nucleophiles, and the size of the α-effect, characterized by the ratio of the second-order rate constants for reactions of HOO− and OH− anions with NPDEPS, remains practically constant and reaches a value of ∼50-fold.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 6, pp. 357–363, November–December, 2006. 相似文献
15.
V. M. Koshelev T. D. Truskanova V. F. Cherstkov D. V. Romanov N. V. Vasili'ev 《Russian Chemical Bulletin》2005,54(7):1675-1679
Defluorination of polyfluorinated acylimines by zinc on heating in dioxane gave polyfluorinated oxazoles. The behavior of
polyfluorinated oxazoles in nucleophilic substitution was studied.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1626–1629, July, 2005. 相似文献
16.
The possibility to prepare fused tetrazole- and imidazole derivatives by iodocyclization in moderate to excellent yields is demonstrated. In some examples the cyclizations were not following Baldwin's rules entirely, i.e. exo-selectivity. Nucleophilic substitution of the formed iodides gave different results depending on the hardness of the nucleophile. Thus, elimination of the iodide could be a problem but a substitution reaction with ethyl potassium xanthate and a radical reaction using acrylonitrile were tolerated. In addition, we showed that it is possible to selectively use three iodo substituents individually in one of the fused imidazole derivatives. 相似文献
17.
Woohyung Jeon Ramil Baiazitov Matteo Chierchia Kyle Niederer Hongyu Ren Young-Choon Moon Bradley B. Gilbert 《Helvetica chimica acta》2023,106(9):e202300091
A variety of di- and trifluoromethyl-s-triazines are prepared following straightforward synthetic protocols from simple, commercially available starting materials. Trichloromethyl-substituted triazine electrophiles are obtained in good yield and react with amine nucleophiles to afford aminotriazine products in good to excellent yield. The nucleophilic aromatic substitution reaction is broad in scope and proceeds smoothly with both aromatic and aliphatic (primary, secondary, and branched) amines in the presence of non-participating functional groups including alcohols, carboxylic acids, indoles, and common amine protecting groups. Furthermore, most reactions require only a catalytic amount of 4-DMAP with no stoichiometric base and are complete within two hours at ambient temperature. 相似文献
19.
O. A. Rakltin O. A. Zalesova A. S. Kulikov N. N. Makhova T. I. Godovikova L. I. Khmel'nitskii 《Russian Chemical Bulletin》1993,42(11):1865-1870
Diazotization of aminofurazans (1) and 4-aminofuroxans (2) with nitrosylsulfuric acid in a mixture of conc. H2SO4 and H3PO4 has been studied and offered as a general method for preparing furazanyl- (3) and furoxanyldiazonium (4) salts. It has been shown that reactions with the retention of the N-N-group (azo coupling, formation of triazenes and azides) are typical of salts3 and4, while elimination of the N2 molecule (Sandmeyer reaction, hydrolysis, reduction) is not typical.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1949–1953, November, 1993. 相似文献