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1.
Org Lett ; 3(17): 2673-6, 2001 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-11506606

RESUMEN

[reaction: see text]. A new method to produce benzimidazolium salts based on a successive Buchwald-Hartwig amination and ring closure is reported. A variety of different benzimidazolium salts can be prepared using this procedure. Amines that bear an alpha-chiral group undergo the reaction to furnish chiral benzimidazolium salts. The salts that lack a C2 substituent on the heterocycle are readily deprotonated to give nucleophilic carbenes.


Asunto(s)
Aminas/química , Bencimidazoles/síntesis química , Furanos/síntesis química , Piranos/síntesis química , Cristalografía por Rayos X , Furanos/química , Cinética , Piranos/química , Sales (Química) , Termodinámica
2.
Org Lett ; 2(15): 2271-4, 2000 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-10930261

RESUMEN

The Grubbs 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene-substituted ruthenium complex 1 catalyzed ethylene-alkyne cross-metathesis and was shown to tolerate free hydroxyl groups and coordinating functionality at the propargylic and homopropargylic positions. Hindered and enantiomerically enriched 1-substituted alkynes also react efficiently under the reported conditions.


Asunto(s)
Alquinos/química , Etilenos/química , Compuestos de Rutenio/química , Compuestos de Rutenio/metabolismo , Alquinos/metabolismo , Catálisis , Quelantes/metabolismo , Etilenos/metabolismo , Cinética , Estereoisomerismo
3.
Proc Natl Acad Sci U S A ; 94(15): 7825-30, 1997 Jul 22.
Artículo en Inglés | MEDLINE | ID: mdl-9223271

RESUMEN

The natural product rapamycin has been used to provide temporal and quantitative control of gene expression in animals through its ability to interact with two proteins simultaneously. A shortcoming of this approach is that rapamycin is an inhibitor of cell proliferation, the result of binding to FKBP12-rapamycin-associated protein (FRAP). To overcome this limitation, nontoxic derivatives of rapamycin bearing bulky substituents at its C16-position were synthesized, each in a single step. The isosteric isopropoxy and methallyl substituents with the nonnatural C16-configuration abolish both binding to FRAP and inhibition of T cell proliferation. Binding proteins for these derivatives were identified from libraries of cDNAs encoding mutants of the FKBP12-rapamycin-binding (FRB) domain of FRAP by using a mammalian three-hybrid transcription assay. Targeting of the mutations was guided by the structure of the FKBP12-rapamycin-FRB ternary complex. Three compensatory mutations in the FRB domain, all along one face of an alpha-helix in a rapamycin-binding pocket, were identified that together restore binding of the rapamycin derivatives. Using this mutant FRB domain, one of the nontoxic rapamycin derivatives induced targeted gene expression in Jurkat T cells with an EC50 below 10 nM. Another derivative was used to recruit a cytosolic protein to the plasma membrane, mimicking a process involved in many signaling pathways.


Asunto(s)
Regulación de la Expresión Génica , Proteínas/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , Animales , Transporte Biológico , Proteínas Portadoras/química , Proteínas Portadoras/genética , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Regulación de la Expresión Génica/efectos de los fármacos , Proteínas de Choque Térmico/química , Proteínas de Choque Térmico/genética , Ligandos , Estructura Molecular , Polienos/farmacología , Sirolimus , Proteínas de Unión a Tacrolimus
4.
J Org Chem ; 61(2): 430-431, 1996 Jan 26.
Artículo en Inglés | MEDLINE | ID: mdl-11666951
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