19 research outputs found
Aminocyanation by the Addition of N–CN Bonds to Arynes: Chemoselective Synthesis of 1,2-Bifunctional Aminobenzonitriles
An
efficient aminocyanation by the direct addition of aryl cyanamides
to arynes is described, enabling incorporation of highly useful amino
and cyano groups synchronously via cleavage of inert N–CN bonds,
affording synthetically useful 1,2-bifunctional aminobenzonitriles.
The postsynthetic functionalization of the aminocyanation products
allows diverse formation of synthetically important derivatives such
as drug molecule Ponstan and fused heterocycles
Iron-Catalyzed, Chelation-Induced Remote C–H Allylation of Quinolines via 8‑Amido Assistance
An
iron-catalyzed, 8-amido-enabled regiodivergent C–H allylation
of quinolines is described. This reaction represents a rare example
of chelation-induced geometrically inaccessible C–H functionalization,
allowing for the highly regio- and stereoselective preparation of
either the C5- or the C4-allylated quinoline scaffolds regiocontrolled
by the catalytic systems
Iron-Catalyzed Regio- and Stereoselective Chlorosulfonylation of Terminal Alkynes with Aromatic Sulfonyl Chlorides
Terminal alkynes react with aromatic sulfonyl chlorides in the presence of an iron(II) catalyst and a phosphine ligand to give (<i>E</i>)-β-chlorovinylsulfones with 100% regio- and stereoselectivity. Various functional groups, such as chloride, bromide, iodide, nitro, ketone, and aldehyde, are tolerated under the reaction conditions. Addition of tosyl chloride to a 1,6-enyne followed by radical 5-<i>exo</i>-<i>trig</i> cyclization gave an exocyclic alkenylsulfone
Site-Selective Silylation of Aliphatic C–H Bonds Mediated by [1,5]-Hydrogen Transfer: Synthesis of α‑Sila Benzamides
The
first example of site-selective silylation of CÂ(sp<sup>3</sup>)–H
bonds mediated by a [1,5]-hydrogen transfer is reported.
This reaction occurs selectively at the α-position of benzamides
with a combination of <i>tert</i>-butylmagnesium chloride
and a catalytic amount of 4,4′-di-<i>tert</i>-butylbipyridine
(dtbpy) ligand and provides a facile route for the creation of biologically
interesting α-sila benzamides. Late-stage functionalization
of the incorporated silyl moieties facilitates the synthesis of <i>N</i>-formyl, <i>cis</i>-enamine, β-hydroxyl,
amino, and pyrrole-containing derivatives
Synthesis of 2‑Benzylphenyl Ketones by Aryne Insertion into Unactivated C–C Bonds
A transition-metal-free
procedure to access to functionalized 2-benzylphenyl
ketones is described by direct insertion of arynes into benzylic C–C
bonds. This reaction was promoted by cesium fluoride at room temperature,
allowing the products to form in high selectivity and achieve good
functional group tolerance
Synthesis of 2‑Benzylphenyl Ketones by Aryne Insertion into Unactivated C–C Bonds
A transition-metal-free
procedure to access to functionalized 2-benzylphenyl
ketones is described by direct insertion of arynes into benzylic C–C
bonds. This reaction was promoted by cesium fluoride at room temperature,
allowing the products to form in high selectivity and achieve good
functional group tolerance
Site-Selective Silylation of Aliphatic C–H Bonds Mediated by [1,5]-Hydrogen Transfer: Synthesis of α‑Sila Benzamides
The
first example of site-selective silylation of CÂ(sp<sup>3</sup>)–H
bonds mediated by a [1,5]-hydrogen transfer is reported.
This reaction occurs selectively at the α-position of benzamides
with a combination of <i>tert</i>-butylmagnesium chloride
and a catalytic amount of 4,4′-di-<i>tert</i>-butylbipyridine
(dtbpy) ligand and provides a facile route for the creation of biologically
interesting α-sila benzamides. Late-stage functionalization
of the incorporated silyl moieties facilitates the synthesis of <i>N</i>-formyl, <i>cis</i>-enamine, β-hydroxyl,
amino, and pyrrole-containing derivatives
Regio- and Chemoselective Kumada–Tamao–Corriu Reaction of Aryl Alkyl Ethers Catalyzed by Chromium Under Mild Conditions
Acting
as an environmentally benign synthetic tool, the cross-coupling
reactions with aryl ethers via C–O bond activation have attracted
broad interest. However, the functionalizations of C–O bonds
are mainly limited to nickel catalysis, and selectivity has long been
a prominent challenge when several C–O bonds are present in
the one molecule. We report here the first chromium-catalyzed selective
cross-coupling reactions of aryl ethers with Grignard reagents by
the cleavage of C–OÂ(alkyl) bonds. Diverse transformations were
achieved using simple, inexpensive chromiumÂ(II) precatalyst combining
imino auxiliary at room temperature. It offers a new avenue for buildup
functionalized aromatic aldehydes with high efficiency and selectivity
Predisposing factors of recurrent vulvovaginal candidiasis III.
SOUHRN V práci jsme se zabĂ˝vali problematikou rekurentnĂ vulvovaginálnĂ kandidĂłzy. VulvovaginálnĂ kandidĂłza patřà mezi nejběžnÄ›jšà genitálnĂ infekce. PĹ™edpokládá se, Ĺľe 75% Ĺľen v reprodukÄŤnĂm vÄ›ku minimálnÄ› 1krát za Ĺľivot prodÄ›lá ataku VVK. RVVK je nejÄŤastÄ›ji definována ÄŤtyĹ™mi nebo vĂce atakami symptomatickĂ˝ch vaginálnĂch kandidĂłz bÄ›hem jednoho roku. Incidence tohoto onemocnÄ›nĂ nenĂ pĹ™esnÄ› známá, pĹ™edpokládá se okolo 5%, nÄ›kterĂ© studie uvádÄ›jĂ aĹľ 8% Ĺľen v reprodukÄŤnĂm vÄ›ku. Naše studie uvádĂ incidenci 7,6%. Pro účel tĂ©to práce byly vypracovány dotaznĂky, pomocĂ nichĹľ jsme se snaĹľili zjistit moĹľnĂ© predispoziÄŤnĂ faktory tohoto onemocnÄ›nĂ. KaĹľdĂ˝ dotaznĂk se skládal z 17 stran a obsahoval 49 otázek. PlnĂ© znÄ›nĂ dotaznĂku je uvedeno v pĹ™Ăloze. DotaznĂk obsahoval 15 silnÄ› orámovanĂ˝ch otázek urÄŤenĂ˝ch jen Ĺľenám, kterĂ© majĂ zkušenost s opakovanĂ˝m kvasinkovĂ˝m zánÄ›tem. Hodnotili jsme skupinu 184 Ĺľen, kterĂ© vyplnily náš dotaznĂk (návratnost byla 184 ze 199 dotaznĂkĹŻ, coĹľ je 92,5%). PĹ™i vyhodnocovánĂ otázek dotaznĂku jsme popsali nÄ›kolik faktorĹŻ, kterĂ© zvyšujĂ riziko vĂ˝skytu RVVK, jsou to zejmĂ©na tyto: konzumace potravin s vysokĂ˝m obsahem sacharidĹŻ, trvalĂ© pouĹľĂváni intimek i mimo menstruaci, dlouhá horká sprcha, nošenĂ tÄ›snĂ˝ch kalhot, kouĹ™enĂ cigaret, vyššà poÄŤet sexuálnĂch partnerĹŻ, vyholovánĂ ochlupenĂ v klĂnÄ› z vÄ›tšĂ...1 ABSTRACT In this study we are dealing with problems of recurrent vulvovaginal candidiasis. Vulvovaginal candidiasis is one of the most frequent genital infections. It is hypothesized that 75% of woman experience during their reproductive age at least 1 episode of VVC in their lifetime. RVVC can be defined as four or more attacks of symptomatic vulvovaginal candidiasis in 12 month period. The true incidence of RVVC remains unknown. Estimates over many years suggest that the incidence is approximately 5%, another recent study determined that the incidence is approximately 8% woman during their reproductive age. Our study determined that the incidence is approximately 7,6%. For purpose of this study were made questionnaires, which help to examine possible risk factors of RVVC. Each questionnaire is composed of 17 pages and contains 49 questions. Fulltext of the questionnaire is showed in enclosure. Questionnaire contain 15 heavily-circumscribed questions addressed only to woman, that have experience repeated episodes of vulvovaginal candidiasis. A sample of 199 woman were interviewed, 184 of them completed our questionnaire (92,5%). By evaluation of the questionnaire we have described number of factors, which increase risk of RVVC, these are primarily: diet high in sugar, continuous use of panty-liners in...Katedra biologickĂ˝ch a lĂ©kaĹ™skĂ˝ch vÄ›dDepartment of Biological and Medical SciencesFaculty of Pharmacy in Hradec KrálovĂ©Farmaceutická fakulta v Hradci Králov
Kumada Arylation of Secondary Amides Enabled by Chromium Catalysis for Unsymmetric Ketone Synthesis under Mild Conditions
The
synthesis of aromatic ketones by chromium-catalyzed Kumada
arylation of secondary amides with organomagnesium reagents is described.
This reaction was enabled by using low-cost chromiumÂ(III) salt as
a precatalyst, combined with trimethylsilyl chloride as an additive,
and presents a rare example of catalytic transformation of secondary
amides to ketones at room temperature. It was shown that catalytically
active low-valent chromium species might be responsible for the amide–ketone
exchange by mechanism involving the activation of benzimidate intermediate