Regioselective Introduction Of Substituents Research Articles

ChemInform Abstract: An Efficient Synthetic Approach Towards Fully Functionalized Tetronic Acids: The Use of 1,3‐Dioxolane‐2,4‐diones as Novel Protected‐Activated Synthons of α‐Hydroxy Acids.

AbstractUtilization of optically active α‐hydroxy acids allows for the enantiocontrolled preparation of tetronic acids.

An efficient synthetic approach towards fully functionalized tetronic acids: the use of 1,3-dioxolane-2,4-diones as novel protected-activated synthons of α-hydroxy acids

A new strategy for the synthesis of tetronic acids with control over the regioselective introduction of substituents at the C-5 position has been developed. The construction of the densely functionalized quaternary carbon center within these molecules is of great importance. The key element for the proposed protocol was the utilization of O-carboxyanhydrides (OCA's) of optically active α-hydroxy acids, as promising bidentate protective/activating precursors. The structure of the new compounds was investigated by using NMR spectral data and X-ray structural analyses.

Regioselective Introduction of Substituents to the meso-Position of Pyrromethenone Derivative – Application to the Synthesis of Sterically Fixed Phytochrome Chromophore Anchored to the C15 meso-Position

Regioselective Introduction of Substituents to the meso-Position of Pyrromethenone Derivative – Application to the Synthesis of Sterically Fixed Phytochrome Chromophore Anchored to the C15 meso-Position

Multicomponent Synthesis of 4-Aminophthalazin-1(2H)-ones by Palladium-Catalyzed Isocyanide Insertion

4-Aminophthalazin-1(2H)-ones (APOs) are underexplored heterocyclic compounds with promising and diverse biological activities. The classical synthesis of these compounds is tedious and does not allow the regioselective introduction of substituents. Here, we present our full studies on the Pd-catalyzed cross-coupling of substituted o-(pseudo)halobenzoates and hydrazines with isocyanide insertion allowing straightforward access to diversely substituted APOs. We illustrate the advantages of this method compared to other approaches and describe solutions for the limitations we encountered. In addition, we have developed efficient diversifications of this heterocyclic scaffold that allow access to more diverse APOs as well as novel heterocyclic scaffolds.

Synthesis of modified proanthocyanidins: introduction of acyl substituents at C-8 of catechin. Selective synthesis of a C-4 → O → C-3 ether-linked procyanidin-like dimer

The regioselective introduction of substituents at C-8 of (+)-catechin is described, leading to the synthesis of several catechin derivatives with various substitution patterns to be used for the further synthesis of modified proanthocyanidins. Thereafter, a new 3-O-4 ether-linked procyanidin-like derivative was synthesized. Its formation was selectively achieved through TiCl 4-catalyzed condensation of 4-(2-hydroxyethoxy)tetra- O-benzyl catechin with the 8-trifluoroacetyl adduct of tetra- O-benzyl catechin.

ChemInform Abstract: Synthesis of 3,4‐Disubstituted 3,4‐Dihydro‐2‐pyrones via 2‐(Silyloxy)pyrylium Salts: Regioselective Introduction of Substituents into 2‐Pyrones.

AbstractSilylation of the pyrone (I) with the silyl triflate (II) gives the pyrylium salt (III) which reacts with the cuprates (IV) to produce regioselectively the pyrans (V).

Synthesis of 3,4-disubstituted 3,4-dihydro-2-pyrones via 2-(silyloxy)pyrylium salts: regioselective introduction of substituents into 2-pyrones

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of 3,4-disubstituted 3,4-dihydro-2-pyrones via 2-(silyloxy)pyrylium salts: regioselective introduction of substituents into 2-pyronesTakashi Kume, Toshikatsu Kojima, Hideharu Iwasaki, Yohsuke Yamamoto, and Kinya AkibaCite this: J. Org. Chem. 1989, 54, 8, 1931–1935Publication Date (Print):April 1, 1989Publication History Published online1 May 2002Published inissue 1 April 1989https://doi.org/10.1021/jo00269a034RIGHTS & PERMISSIONSArticle Views378Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (645 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

ChemInform Abstract: Directed Regioselective Lithiation of (η6‐Arene)chromium Tricarbonyl Complexes: Regioselective Synthesis of Anthraquinones and Calamenenes.

AbstractWie Untersuchungen zeigen, werden die Cr‐Komplexe (I) bzw. (II) selektiv in 4‐ bzw. 6‐Stellung lithiiert.

Directed regioselective lithiation of (η 6-arene) chromium tricarbonyl complexes : Regioselective synthesis of anthraquinones and calamenenes

(3-Methoxybenzylalcohol)chromium tricarbonyl ( 10) and (7-methoxy-1-tetralol)chromium tricarbonyl ( 12) are selectively lithiated at the 4- and 6-positions, respectively, by treatment with n-BuLi-TMEDA. Since the directed lithiation of the corresponding chromium free arenes normally proceeds at the 2-and 8-positions, complementarily substituted arenes can be prepared by using the chromium tricarbonyl complexes. The difierent position of lithiation is explained by the relative configuration of the chromium tricarbonyl group in the (arene)Cr(CO) 3 and electrostatic factors. Some anthraquinones, 31, 36, 42, and 7-hydroxycalamenenes, 43, have been synthesized through the stereo- and regioselective introduction of substituents by means of(η 6-arene)chromium tricarbonyl complexes.