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1.
Tetrahedron ; 71(35): 5741-5757, 2015 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-26273110

RESUMEN

A total synthesis of the aglycone of IB-00208 was accomplished in 22 steps using a newly developed approach towards polycyclic 1,4-dioxygenated xanthones from benzocyclobutenones. The generality of this entry to xanthones was initially established on several model systems before it was successfully applied to the construction of the hexacyclic core of the natural product. A new and potentially general approach towards angularly-fused benzocyclobutenones using ring-closing metathesis (RCM) was also developed.

2.
Tetrahedron ; 67(35): 6524-6538, 2011 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-21804649

RESUMEN

We report the first total synthesis of the complex C-aryl glycoside isokidamycin, the epimer of the naturally-occurring pluramycin antibiotic kidamycin. The synthesis features a highly efficientDiels-Alder reaction between a substituted naphthyne and a glycosylatedfuran to form the anthracene core bearing a pendant angolosamine C-glycoside. The regiochemical outcome of the Diels-Alder reaction was controlled by employing a disposable silicon-tether to link the reactive napthyne and the glycosyl furan, rendering the cycloaddition intramolecular. The benzopyranone moietyof the aromatic nucleus was appended by cyclization of a functionalized vinylogous amide onto an advanced anthrol intermediate. The vancosamine amino glycoside was introduced by an O→C-glycoside rearrangement that produced the ß-anomer. Subsequent refunctionalizations then led to isokidamycin.

3.
Front Bioinform ; 1: 826370, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-36303775

RESUMEN

The nascent field of microbiome science is transitioning from a descriptive approach of cataloging taxa and functions present in an environment to applying multi-omics methods to investigate microbiome dynamics and function. A large number of new tools and algorithms have been designed and used for very specific purposes on samples collected by individual investigators or groups. While these developments have been quite instructive, the ability to compare microbiome data generated by many groups of researchers is impeded by the lack of standardized application of bioinformatics methods. Additionally, there are few examples of broad bioinformatics workflows that can process metagenome, metatranscriptome, metaproteome and metabolomic data at scale, and no central hub that allows processing, or provides varied omics data that are findable, accessible, interoperable and reusable (FAIR). Here, we review some of the challenges that exist in analyzing omics data within the microbiome research sphere, and provide context on how the National Microbiome Data Collaborative has adopted a standardized and open access approach to address such challenges.

4.
J Am Chem Soc ; 132(44): 15528-30, 2010 Nov 10.
Artículo en Inglés | MEDLINE | ID: mdl-20958036

RESUMEN

The synthesis of isokidamycin, which represents the first total synthesis of a bis-C-aryl glycoside natural product in the pluramycin family, has been completed. The synthesis features the use of a silicon tether as a disposable regiocontrol element in an intramolecular Diels-Alder reaction between a substituted naphthyne and a glycosyl furan and a subsequent O→C-glycoside rearrangement.


Asunto(s)
Aminoglicósidos/química , Aminoglicósidos/síntesis química , Estructura Molecular
5.
Org Lett ; 17(1): 114-7, 2015 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-25513888

RESUMEN

Hexacyclic xanthone natural products such as IB-00208 present a formidable challenge in organic synthesis. A new approach to polycyclic 1,4-dioxygenated xanthones from benzocyclobutenones has been developed and applied to the first total synthesis of the aglycone of IB-00208. The 22-step synthesis features an acetylide stitching process that joins an aryl aldehyde with an angularly fused benzocyclobutenone, which was prepared by a ring-closing metathesis reaction. The resulting acetylenic benzocyclobutenone diol underwent a Moore rearrangement to give an intermediate that was further elaborated to the aglycone of IB-00208 as a mixture of hydroquinone-quinone tautomers.


Asunto(s)
Productos Biológicos/síntesis química , Glucósidos/síntesis química , Xantenos/síntesis química , Xantonas/química , Alcoholes/química , Productos Biológicos/química , Glucósidos/química , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Xantenos/química
6.
Org Lett ; 6(19): 3305-8, 2004 Sep 16.
Artículo en Inglés | MEDLINE | ID: mdl-15355038

RESUMEN

[reaction: see text] The total synthesis of (+)-cocaine is described. An extension of the recently reported proline catalyzed intramolecular enol-exo-aldol reaction to a meso-dialdehyde provided the tropane ring skeleton directly with good enantiomeric excess. The meso-dialdehyde was prepared using a 2-azaallyllithium [3 + 2] cycloaddition to generate a cis-2,5-disubstituted pyrrolidine. Overall, the synthesis proceeded in 6.5% yield and 86% ee over 14 linear steps starting from commercially available 3-benzyloxy-1-propanol.


Asunto(s)
Aldehídos/química , Cocaína/síntesis química , Prolina/metabolismo , Catálisis , Cocaína/análisis , Ciclización , Estructura Molecular , Pirrolidinas/síntesis química , Estereoisomerismo
7.
Org Lett ; 4(18): 3099-102, 2002 Sep 05.
Artículo en Inglés | MEDLINE | ID: mdl-12201726

RESUMEN

[reaction: see text] Transmetalation of tin-bearing cyclic imidates gave 2-azaallyllithiums that underwent [pi6s + pi4s] cycloadditions with cycloheptatriene to produce tricyclic adducts, which may be useful as analogs of cocaine. The peri- and stereoselectivity of this process are discussed.


Asunto(s)
Cocaína/análogos & derivados , Compuestos Heterocíclicos de Anillo en Puente/síntesis química , Compuestos Aza/química , Cicloheptanos/química , Electrones , Compuestos de Litio/química , Polienos
8.
Org Lett ; 14(6): 1604-7, 2012 Mar 16.
Artículo en Inglés | MEDLINE | ID: mdl-22397735

RESUMEN

A three-step procedure to access fused pyridines has been developed utilizing inexpensive amino acids and alkenols to form the key oxazole precursors. Yields are good to excellent and provide a rapid and inexpensive route to a range of pharmacologically and biologically valuable fused pyridines with difficult to access substitution patterns.


Asunto(s)
Aminoácidos/química , Oxazoles/síntesis química , Piridinas/síntesis química , Catálisis , Ciclización , Estructura Molecular , Oxazoles/química , Piridinas/química
9.
J Org Chem ; 69(19): 6419-26, 2004 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-15357603

RESUMEN

A Kumada cross-coupling reaction involving organomagnesium reagents and (3-methylthio-2-azaallyl)stannanes with a Ni(0) catalyst provided cyclic nonstabilized (2-azaallyl)stannanes in moderate to good yields. Primary alkyl, aryl, and allylic organomagnesium reagents can be used as the cross-coupling partner. In general, NiCl(2)dppp in toluene at room temperature provided the shortest reaction times and most consistent yields. The azomethine ylides and 2-azaallyllithium species derived from these stannanes were shown to undergo efficient [3 + 2] cycloaddition reactions to provide azabicyclo[n.2.1]alkanes as the endo cycloadducts. These cycloadducts were found to be useful as starting materials for further elaboration into aza-bridged bicyclic natural and unnatural products of biological interest. Although cyclic 2-azaallyllithium species have been generated previously, this work reports the first generation and cycloaddition of entirely nonstabilized 2-azaallyllithium species. In addition a novel extension of the Kumada coupling was developed to allow for the preparation of the cyclic (2-azaallyl)stannanes, which are precursors to the nonstabilized 2-azaallyllithium species.


Asunto(s)
Litio/química , Compuestos de Estaño/química
10.
J Org Chem ; 69(4): 1235-47, 2004 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-14961676

RESUMEN

2-Azaallyllithium species [R(1)CH(-)N=C(X)R(2)Li(+), where R(1) and R(2) are alkyl and X = OMe] were generated by tin-lithium exchange of (2-azaallyl)stannanes and underwent [pi4s+pi2s] and [pi6s+pi4s] cycloadditions with cyclic dienes and trienes, respectively, to generate novel bridged azabicyclic compounds in a highly diastereoselective endo fashion. The periselectivity using cycloheptatriene was modest, producing a 1:1 mixture of [pi6s+pi4s] and [pi4s+pi2s] adducts. The reactions of 2-azaallyllithium species with dienes proceeded by a [pi4s+pi2s] pathway. The cycloadducts derived from cyclic 2-azaallyllithium species possess the 7-azabicyclo[2.2.1]heptane (tropane) or 8-azabicyclo[3.2.1]octane ring system and have been elaborated into cocaine-like analogues.


Asunto(s)
Cocaína/análogos & derivados , Compuestos Heterocíclicos de Anillo en Puente/síntesis química , Litio/química , Compuestos Organometálicos/química , Polienos/química , Compuestos Aza/química , Ciclización , Espectroscopía de Resonancia Magnética
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