共查询到20条相似文献,搜索用时 557 毫秒
1.
David M. Forkey 《Journal of mass spectrometry : JMS》1969,2(3):309-315
The mass spectra of the non-benzenoid aromatic heterocycles 2H- and 2-methyl-2H-cyclopenta[d]pyridazine and several deuterated analogs have been analyzed. The majority of the nitrogen lost from these heterocycles occurs as HCN OR H2CN. The deuterium labeling suggests a rearrangement of the molecular ion prior to fragmentation. 相似文献
2.
A simple one-step synthesis of a new class of fluorinated heterocycles, 4-fluoro-3-oxazolines, from diarylmethanimines, trifluoroacetophenones and CF2Br2 is described. The reaction proceeds via the sequential formation of difluorocarbene and a gem-difluorosubstituted NH-azomethine ylide, followed by 1,3-dipolar cycloaddition with a ketone. 相似文献
3.
综述了近年来利用一些新型的含氟砌块,通过它们的环加成反应来高效地合成 含氟杂环化合物的研究,其中包括以下两个部分:(1)用1,3—偶极环加成反应合 成五元含氟杂环化合物;(2)用杂原于Diels-Alder反应合成六元含氟杂环化合物. 相似文献
4.
Dr. Kostiantyn P. Melnykov Olha Tavlui Artem Skreminskiy Yuliya O. Kuchkovska Prof. Dr. Oleksandr O. Grygorenko 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(55):e202201601
The physicochemical properties (pKa(H), log P, and aqueous solubility) of fluoroalkyl-substituted heterocyclic amines were profiled to facilitate the amines’ rational application in medicinal chemistry research. The features of fluorine-containing compounds were compared to those of the corresponding parent non-fluorinated heterocycles and the corresponding fluorinated n-alkylamines. Amine basicity was observed to change in a monotonic fashion depending on the fluorination pattern. Although the introduction of fluoroalkyl groups had complex effects on the lipophilicity and aqueous solubility of the compounds, possible contributions of the fluorination pattern, ring size, and conformation of the substituent in the ring were addressed for a series of derivatives. The summarized data provide a useful guideline for the application of fluorinated motifs for fine-tuning a compound's properties related to drug discovery. 相似文献
5.
《合成通讯》2013,43(24):4241-4252
Abstract New N-substituted 7-amino-1-nitro-2-heptanone derivatives have been obtained starting from readily accessible 2-(nitromethylidene)hexahydro-1H-azepine. These compounds have been further used as starting materials for the synthesis of some heterocycles with 5-aminopentyl fragment. 相似文献
6.
János T. Csenki Ádám Mészáros Dr. Zsombor Gonda Dr. Zoltán Novák 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(63):15638-15643
The availability and synthesis of fluorinated enamine derivatives such as N-(3,3,3-trifluoropropenyl)heterocycles are challenging, especially through direct functionalization of the heterocyclic scaffold. Herein, a stereoselective N-trifluoropropenylation method based on the use of a bench-stable trifluoropropenyl iodonium salt is described. This reagent enables the straightforward trifluoropropenylation of various N-heterocycles under mild reaction conditions, providing trifluoromethyl enamine type moieties with high stereoselectivity and efficiency. 相似文献
7.
Selectfluor and NFSI exo‐Glycal Fluorination Strategies Applied to the Enhancement of the Binding Affinity of Galactofuranosyltransferase GlfT2 Inhibitors 下载免费PDF全文
Dr. Lidia Dumitrescu Dr. Guillaume Eppe Abdellatif Tikad Dr. Weidong Pan Sandy El Bkassiny Sudagar S. Gurcha Dr. Ana Ardá Prof. Jesús Jiménez‐Barbero Prof. Gurdyal S. Besra Prof. Stéphane P. Vincent 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15208-15215
Two complementary methods for the synthesis of fluorinated exo‐glycals have been developed, for which previously no general reaction had been available. First, a Selectfluor‐mediated fluorination was optimized after detailed analysis of all the reaction parameters. A dramatic effect of molecular sieves on the course of the reaction was observed. The reaction was generalized with a set of biologically relevant furanosides and pyranosides. A second direct approach involving carbanionic chemistry and the use of N‐fluorobenzenesulfonimide (NFSI) was performed and this method gave better diastereoselectivities. Assignment of the Z/E configuration of all the fluorinated exo‐glycals was achieved based on the results of HOESY experiments. Furthermore, fluorinated exo‐glycal analogues of UDP‐galactofuranose were prepared and assayed against GlfT2, which is a key enzyme involved in the cell‐wall biosynthesis of major pathogens. The fluorinated exo‐glycals proved to be potent inhibitors as compared with a series of C‐glycosidic analogues of UDP‐Galf, thus demonstrating the double beneficial effect of the exocyclic enol ether functionality and the fluorine atom. 相似文献
8.
Some new N-methylimidazoles, oxazoles and thiazoles (compounds 7-15 ) with a keto-function in the 2-position have been synthesized by the reaction of heterocyclic substituted silanes and stannanes with the corresponding acid chlorides. In cases where the silylated heterocycles needed more drastic reaction conditions the use of the stannylated heterocycles was indicated. In the reaction of benzothiazol-2-yltrimethyl-stannane ( 6 ) with acetyl chloride the ester 17 and the bibenzothiazolinylidene 18 were formed. The reaction of 6 with chloromethyl methyl ether afforded the olefin 19 as the only product. Mechanisms for the above reactions are discussed. 相似文献
9.
Tetsuji Yata Dr. Yoshihiro Nishimoto Dr. Kouji Chiba Prof. Dr. Makoto Yasuda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(32):8288-8294
Fluorinated heterocycles have attracted much attention in the pharmaceutical and agrochemical industries. Many strategies have already been developed to achieve the synthesis of fluorinated heterocycles. Formidable challenges remain, however, in the synthesis of fluorinated isocoumarin derivatives that are among the most alluring structural motifs. Herein, the indium-catalyzed C−F bond transformation of 2-(2,2-difluorovinyl) benzoates is reported, which are readily accessible compounds, to give a diverse array of fluorinated isocoumarins. The present reaction proceeds smoothly using inexpensive reagents: a catalytic amount of indium salt in the presence of zinc salt. A theoretical calculation of potential energy profiles showed that the reaction consists of oxymetalation with the elimination of alkyl halide and the β-fluorine elimination. 相似文献
10.
Krishna C. Joshi Renuka Jain Anshu Dandia Vandana Sharma 《Journal of heterocyclic chemistry》1986,23(1):97-99
A novel system 2-oxo-1′,2′,4′,5′-tetrahydrospiro[3H-indole-3,3′-1,2,4,5-tetrazine]-6′-thione has been synthesized by the treatment of fluorinated isatins with thiocarbohydrazide in aqueous ethanolic medium. Under exactly similar conditions, N-acetylisatin gave exclusively thiocarbohydrazone. The spiro product, on treatment with acetic acid, gave fluorinated isoindigo. Characterization of these products have been done by elemental analyses, ir, pmr and mass spectral studies. 相似文献
11.
Krishna C. Majumdar Swapan K. Samanta 《Monatshefte für Chemie / Chemical Monthly》2002,36(6):1187-1192
5-(Cyclohex-2-enyl)-1,3-dimethyl-6-hydroxyuracil undergoes regioselective heterocyclization to afford fused tricyclic heterocycles upon treatment with bromine and m-CPBA. However, the same substrate furnished bridged tricyclic heterocycles when treated with N-iodosuccinimide and conc. H2SO4 and a mixture of bridged tricyclic heterocycles and fused tricyclic heterocycles when treated with hexamine hydrotribromide or pyridine hydrotribromide. 相似文献
12.
13.
S. A. Nalet´ko M. G. Pervova M. I. Kodess M. S. Toporova T. I. Gorbunova A. Ya. Zapevalov V. I. Saloutin 《Russian Chemical Bulletin》2017,66(6):1011-1017
The CoCl2-catalyzed reactions of fluorinated 1,2-oxi- and thiiranes with acyl chlorides were studied. It was found that a regioselective heterocycle opening reaction resulted in two isomers having normal and abnormal structure in a ratio predetermined by the substituents in both the starting heterocycles and acyl chlorides. 相似文献
14.
Krishna C. Majumdar Swapan K. Samanta 《Monatshefte für Chemie / Chemical Monthly》2002,133(9):1187-1192
Summary. 5-(Cyclohex-2-enyl)-1,3-dimethyl-6-hydroxyuracil undergoes regioselective heterocyclization to afford fused tricyclic heterocycles
upon treatment with bromine and m-CPBA. However, the same substrate furnished bridged tricyclic heterocycles when treated with N-iodosuccinimide and conc. H2SO4 and a mixture of bridged tricyclic heterocycles and fused tricyclic heterocycles when treated with hexamine hydrotribromide
or pyridine hydrotribromide.
Corresponding author. E-mail: kcm@klyuniv.ernet.in
Received September 27, 2001. Accepted (revised) December 3, 2001 相似文献
15.
Edon Vitaku David T. Smith Prof. Dr. Jon T. Njardarson 《Angewandte Chemie (International ed. in English)》2016,55(6):2243-2247
Nitrogen heterocycles are found in a majority of approved small‐molecule pharmaceuticals, and the number of approved fluorinated drugs is increasing each decade. Therefore, new approaches for accessing fluorinated nitrogen heterocycles are of great significance. A novel, scalable, and metal‐free method for accessing a wide range of fluorinated indoles is described. This oxidative‐dearomatization‐enabled approach assembles 2‐trifluoromethyl NH‐indole products from simple commercially available anilines with hexafluoroacetylacetone in the presence of an organic oxidant. The nature of the aniline N‐capping group is critical for the success of this new reaction. Furthermore, the indole products contain a 3‐trifluoroacetyl group, which can be exploited to access a plethora of useful functional groups. 相似文献
16.
Several 2-alkyl-7-aryltetrahydro-1,6,2-dioxazepines 5a-i have been synthesized by a Meisenheimer-type rearrangement of 3-alkyl-2-aryltetrahydro-1,3-oxazine N-oxides 4a-i . These dioxazepines have not been previously described and for the first time compounds with the tetrahydro-1,6,2-dioxazepine ring-system have been made available. The structure assigned to members of this novel heterocycle is based on elemental analysis, infrared, and 1H nmr spectral evidence. Further definitive evidence for the structure of these heterocycles is provided by an X-ray crystallographic analysis of 5c . 相似文献
17.
A two-stage method has been developed for the synthesis of the methyl ester of 3-bromo-2-(2-hydroxy-2-propyl)-7-oxo-7H-selenolo[2,3-f]chromene-8-carboxylic acid – a new example of a class of selenophene-containing polycyclic heterocycles. The molecular structure
was confirmed by X-ray crystallography. 相似文献
18.
2-Monosubstituted 3-amino-2H-azirines 2 react with several heterocycles containing acidic NH groups via ring expansions, leading to benzo[g][1,2,5]thiadiazocin 1,1-dioxide derivatives 6 and imidazoles 9, 10 , and 13 , respectively. 相似文献
19.
Annette Rahm Anthony Linden Beverly R. Vincent Heinz Heimgartner Manfred Mühlstdt Brbel Schulze 《Helvetica chimica acta》1991,74(5):1002-1010
Ring Enlargement of 1,2-Thiazol-3(2H)-one-1,1-dioxides and 3-Amino-2H-azirines to 4H-1,2,5-Thiadiazocin-6-one-1,1-dioxides Reaction of 3-amino-2H-azirines 2 with the 1,1-dioxides 4 and 7 of 1,2-thiazol-3(2H)-ones and 1,2-thiazoli-din-3-ones, respectively, in i-PrOH at room temperature leads to 4H-1,2,5-thiadiazocin-6(5H)-one-1,1-dioxides 5 (Scheme 2, Table) and the corresponding 7,8-dihydro derivatives 8 (Scheme 4), respectively. The structure of some of the new 8-membered heterocycles as well as the structure of the minor by-product 6 (Scheme 3) have been established by X-ray crystallography (Chapt. 4). The proposed reaction mechanism for the ring expansion to 5 and 8 (Scheme 2) is in accordance with previously published results of reactions of 2 and NH-acidic heterocycles and is further supported by the results of the reaction of 4a and the (1-15N)-labelled aminoazirine 2a *. 相似文献
20.
AbstractA simple and efficient, one-pot strategy for the preparation of 4-methylene-2-thiazolidinethiones has been developed. This protocol involved condensation of primary amines with carbon disulfide in water to generate the dithiocarbamate salts in situ, which coupled with 2,3-dibromopropene, followed by intramolecular cyclization to the corresponding heterocycles in moderate to good yields. 相似文献