Xanthene synthesis

The reaction of methoxy-substituted 1,4-dihydroatomatic systems is a general one. Other condensed systems react ia a similar manner, for example, 3,6-dimethoxy-1,4,S,8-tetrahydronaphtha1ene and derivatives of anthracene (35) and xanthene (36) (74). The proposed method enables synthesis of the tri-and tetracarbocyanines where the whole chromophore is iategrated iato a rigidizing skeleton. Asymmetrical polymethines can also be obtained similarly. 

X-ray structures, 6, 903 Xanthene, 3,6-bis(dimethylamino)-synthesis, 3, 767 Xanthene, 4-cyano-synthesis, 3, 768 Xanthene, 3,6-dialkylamino-application, 3, 879 Xanthene, 2,7-dibromo-dipole moments, 3, 627 Xanthene, 3,4-dihydro-synthesis, 3, 768... 

Xanthene-2-carboxylic acid, 7-hydroxy-9-oxo-synthesis, 3, 837 Xanthenes... 

In the present work, the synthesis of two MIEPs is described and their application for sensing and separation two xanthene dyes - rhodamine and fluorescein - has been reported. 

Polymer supported xanthene derivatives have been used in the solid phase synthesis of 1-aminophosphinic acids, RCH(NH2)PH(0)0H, <%TL1647> and of C-terminal peptide amides <96JOC6326>. Xanthene units also feature in crown ethers <96JCS(P2)2091>, calixarenes <96JOC5670> and in a flexible template for a P-sheet nucleator <96JOC7408>. 

Fluoran compound used as leuco dye needs to have substituent(s) on the xanthene moiety to develop color, though fluoran 1 itself is prepared as a by-product in the synthesis of phenolphthalein from phenol and phthalic anhydride. 

Henkel B, Zeng W, Bayer E. 9-Hydroxy-9-(4-carboxyphenyl)xanthene- a new linker for the synthesis of peptide amides. Tetrahedron Lett 1997 38 3511-3512. 

Meisenbach M, Echner H, Voelter W. New methoxy-substituted 9-phenyl-xanthen-9-ylamine linkers for the solid phase phase synthesis of protected peptide amides. Chem Commun (Cambridge) 1997 849-850. 

Scheme 7.5. Synthesis of the guanidinium modified xanthene ligand a) diethylchlorophosphite b)...

Li JQ, Hu MY, Yao SQ (2009) Rapid synthesis, screening, and identification of xanthone-and xanthene-based fluorophores using click chemistry. Org Lett 11 3008-3011... 

The solution phase synthesis of peptides often results in mixtures of labelled, unlabelled compounds along with other impurities and requires extensive purification. A route using a solid phase approach [polyethylene glycol-poly-styrene PEG-PS derivatised with a xanthen-2-oxovalerate (XAL) linker] was recently developed [193] (Scheme 44). 

Although only a few condensed 5 6 or 5 5 aromatic pyrazole derivatives can be isolated from biological sources, the chemistry of condensed pyrazoles has received considerable interest. Condensed pyrazoles with an indene skeleton can be considered as purine analogues and, as such, are expected to have biological activity. The discovery of the xanthene oxidase inhibitory action of pyrazolo[3,4-fiT pyrimidine and the cAMP phos-phodiasterase inhibitory action of pyrazolo[l,5-a]pyrimidines has stimulated considerable interest in the synthesis of analogues of both ring systems. 

Double lithiation of the xanthene derivative 146 is the key step in an important synthesis of the ligand xantphos 147 Benzofuran 148 is also doubly lithiated by excess BuLi/TMEDA (Scheme 72) . 

Nandi GC, Samai S, Kumar R, Singh MS (2009) An efficient one-pot synthesis of tetrahydrobenzo a xanthene-ll-one and diazabenzo a anthracene-9,11-dione derivatives under solvent free condition. Tetrahedron 65 7129-7134... 

Gao SJ, Tsai CH, Yao CF (2009) A simple and green approach for the synthesis of tetrahydrobenzo a xanthen-ll-one derivatives using tetrabutyl ammonium fluoride in water. Synlett 949-954... 

Khurana JM, Magoo D (2009) pTSA-catalyzed one-pot synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo a xanthen-ll-ones in ionic liquid and neat conditions. Tetrahedron Lett 50 4777 780... 

Wang RZ, Zhang LF, Cui ZS (2009) Iodine-catalyzed synthesis of 12-aryl-8,9,10,12-tetra-hydro-benzo a xanthen-ll-one derivatives via multicomponent reaction. Synth Commun 39 2101-2107... 

Das B, Laxminarayana K, Krishnaiah M, Srinivas Y (2007) An efficient and convenient protocol for the synthesis of novel 12-aryl- or 12-alkyl-8,9,10,12-tetrahydrobenzo a xanthen-ll-one derivatives. Synlett 3107-3112... 

The thioxanthone ring system comprises the nucleus for two of the more efficacious orally active antischitosomal drugs. One synthesis for these compounds starts with the chlorsulfonation of pora-chlorotoluene (21-1) to give the sulfonyl chloride (21-2). Treatment of the product with zinc in aqueous sulfuric acid leads to a reduction of the sulfonyl chloride to form the thiophenol (21-3). The key to the formation of this and related thioxanthones and xanthenes consists of the UUman reaction, which... 

In Section II.C we will present novel tricyclic xanthene derived amino acid templates, which allow the construction of libraries of cyclic conformationally constrained peptide loop mimetics using the split-and-mix method without having to use tagging and deconvolution strategies. In Section III we will focus on parallel and combinatorial approaches devoted to the synthesis of small molecule, non-peptidic compound collections, which in addition offer the possibility to incorporate structural features derived from protein epitope mapping into conformationally constrained peptide mimetics. 

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