Abstract Here, we report a novel “CyClick” strategy for the macrocyclization of peptides that works in an exclusively intramolecular fashion thereby precluding formation dimers and oligomers via intermolecular reactions. The CyClick chemistry is highly chemoselective N‐terminus peptide with C‐terminal aldehyde. In this protocol, conformation internally directs activation backbone amide bond facilitates stable 4‐imidazolidinone‐fused cyclic high diastereoselectivity (>99 %). This method...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCryptospirolepine, a Unique Spiro-nonacyclic Alkaloid Isolated from Cryptolepis sanguinolentaAlbert N. Tackie, Gilbert L. Boye, Maged H. M. Sharaf, Paul Schiff Jr., Ronald C. Crouch, Timothy D. Spitzer, Robert Johnson, John Dunn, Doug Minick, and Gary E. MartinCite this: J. Nat. Prod. 1993, 56, 5, 653–670Publication Date (Print):May 1, 1993Publication History Published online1 July 2004Published inissue 1 May...

The chiral nematic phase of poly-γ-benzyl-<sc>l</sc>-glutamate (PBLG) formed in a chloroform–DMSO co-solvent system can be used as versatile alignment medium for the acquisition high quality anisotropic NMR data molecules varying polarities.

Abstract Here, we report a novel “CyClick” strategy for the macrocyclization of peptides that works in an exclusively intramolecular fashion thereby precluding formation dimers and oligomers via intermolecular reactions. The CyClick chemistry is highly chemoselective N‐terminus peptide with C‐terminal aldehyde. In this protocol, conformation internally directs activation backbone amide bond facilitates stable 4‐imidazolidinone‐fused cyclic high diastereoselectivity (&gt;99 %). This method...

Abstract The condensation of the disodium salt 2‐mercapto‐3‐pyridinol with various ortho ‐nitrohalo‐benzenes to yield a group previously unreported 1‐azaphenoxathiins is described. synthetic pathway and substituent location on products unequivocably demonstrated by Fourier Transform 1 3 C‐nmr. Preliminary pharmacologic evaluation title compounds as potential CNS depressant agents also reported.

Abstract The crystal and molecular structure of the 7‐ 8‐chloro analogs 1‐azaphenoxathiin system are described. In contrast to previous compounds possessing antipsychotic type activity, title both nearly planar, demonstrate significant substituent location sensitivity, with 7‐chloro analog exhibiting biologic activity while isomer is devoid activity. relationship these isosterically related phenothiazines in terms design geometry considerations also

A method is presented for the separation and identification of a new N-acetyl keto derivative fumonisin B1 (FB1) produced in solid corn culture. Cultures Fusarium proliferatum (M-1597) were purified using preparative hplc, was detected by negative-ion esms. Structures confirmed 1H- 13C-nmr spectroscopy. The differs from FB1 that tricarballylic acid functionality at C-15 position eicosane backbone replaced ketone amino group acetylated. Direct analysis culture material electrospray lc/ms...

Abstract The preparation of 1,3-dinitrophenoxathiin represents the first reported synthesis phenoxathiin ring system. Based on known relative nucleophilicities either an unprecedented reversal or occurrence a Smiles Rearrangement would be required to account for substituent locations. re-examination this with confirmation actual locations by 13C-nmr and correction original literature is described.

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Abstract The synthesis of 2‐azathianthrene ([1,4]benzodithiino[2,3‐c]pyridine), the only remaining monoazathianthrene yet to be reported, is described. Attempts at direct condensation disubstituted pyridines with dianion 1,2‐dimercaptobenzene were generally unsuccessful requiring that alternative pyridine 1‐oxides employed. title compound was characterized by physical means including 13 C‐nmr spectroscopy. One analog, 4‐nitro‐2‐azathianthrene also studied X‐ray crystallographic means;...

Abstract Reaction of the dianion 3‐hydroxypyridine‐2(1 H )‐thione with 5‐chloro‐4‐nitro‐1‐methylimidazole in N,N ‐dimethylformamide led to formation 5‐(3′‐hydroxypyridyl‐2′‐thio)‐4‐nitro‐1‐methylimidazole, which failed cyclize desired pyrid[1,4]oxathiinoimidazole derivative. In an effort determine why intermediate phenolate sulfide had cyclize, crystal structure isolated product was determined. The refined R = 0.036.

A novel oxobenzylisoquinoline alkaloid, thalprzewalskiinone (1), was isolated from the roots of Thalictrum przewalskii, and its structure established via spectroscopic analysis. Five other alkaloids were isolated: protoberberines pseudocoptisine berberine, aporphines (+)-N-methylnantenine (+)-magnoflorine, simple isoquinolone N-methyl-6,7-dimethoxyisoquinolone. Isovanillin also this extract.

The molecule of the title compound, 5,10-dithia-1,4,6,9-tetraaza-5,10-dihydroanthracene, lies around an inversion center and is nearly planar maximum deviation from planarity 0.018(1) A for S5]. As a result molecule, C-S-C angle, 105.74 (7) o , among largest observed thianthrenes, as are C-C-S angles central ring which 126.68 (11) 127.57

Abstract As a result of studies dealing with the synthesis 1‐azaphenoxathiins, benzo[1″,2″:5,6:5″,4″:5′,6′]bis[1,4]oxathiino[3,2‐ b :3′,2′‐ ']dipyridine was examined. Unique evidence solvent participation in these compounds by structure elucidation novel minor by‐product formed during title compound is also reported.

Abstract The generation of the dianion 3‐mercaptopyridin‐2(1 H )‐thione with triethylamine in N,N ‐dimethylform‐amide followed by reaction presence 2‐chloronitrobenzene fails to give 1‐azathianthrene which is formed good yield when sodium hydride was employed as base. principle product isolated from instead 1,6‐diazathianthrene. Mechanistic considerations are discussed.

A direct comparison of the spectral data for synthetic 2-methyl-6,7-dimethoxy-3'-methoxy-4'-hydroxyoxobenzylisoquinoline iodide (1) and its positional isomer 2-methyl-6,7-dimethoxy-3'-hydroxy-4'-methoxyoxobenzylisoquinoline (2) with obtained oxobenzylisoquinoline alkaloid thalprzewalskiinone revealed that original structural assignment as 1 was in error. These results mandate revision structure to (2).

Abstract Phthaloyl‐2′‐nitrophenylhydrazide undergoes ring closure involving nucleophilic attack of the hydrazide on carboxylic acid in dilute aqueous solution to form corresponding N ‐substituted phthalimide. Structure resulting phthalimide was unequivocally confirmed by 13 C‐nmr.

Abstract As a continuation of recent study on the synthesis bis [1,4]oxathiinodipyridine ring system, we would now like to report preparation 7‐chlorobenzo[1″,2″:5,6:3″,4″:5′,6′]‐ [1,4]oxathiino[3,2‐ b : 3′,2′‐ ]dipyridine. Although potentially complex reaction with several products possible, title compound was formed exclusively, suggesting considerable mechanistic selectivity. The characterization product by FT‐ 1 H‐nmr as well its mass spectral fragmentation pathways are also reported.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of methylaryloxypropanolaminesThomas L. Lemke, Robert Boblitt, George A. Capiton, Lindley Cates, and Gary E. MartinCite this: J. Org. Chem. 1978, 43, 10, 2079–2082Publication Date (Print):May 1, 1978Publication History Published online1 May 2002Published inissue 1 1978https://pubs.acs.org/doi/10.1021/jo00404a062https://doi.org/10.1021/jo00404a062research-articleACS PublicationsRequest reuse permissionsArticle...

Abstract Nitro‐groups positioned ortho to thio‐esters have been shown engage in strong, non‐bonded intramolecular interactions between the sulfur atom and one of nitro‐group oxygens. The effect sulfur‐nitro group oxygen interaction on chemical reactivity at 9‐nitro‐1‐azaphenoxathiin is reported. Conditions which normally produce sulfone exclusively yield sulfoxide with only a minimal quantity produced. Protracted periods reflux are required from sulfoxide.

Abstract The nucleoside derivative 1-(3-azido-2,3-dideoxy-beta-D-ribo-hexofuranosyl)thymine has been synthesized from 3-0-benzyl-1,2-0-isopropylidene-alpha-D-glucofuranose-5,6-carbonate in an overall yield of 16%. key step the synthesis involves selective deacetylation a having cyclic carbonate moiety.

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