76 research outputs found
Dichlorodioxomolybdenum(VI) complexes: useful and readily available catalysts in organic synthesis
Molybdenum(VI) dichloride dioxide (MoO2Cl2), and its addition complexes [MoO2Cl2(L)n; L = neutral ligand], are commercially or easily available and inexpensive transition-metal complexes based on a non-noble metal that can be applied as catalysts for various organic transformations. This short review aims to present the most significant breakthroughs in this field.Ministerio de EconomĂa y Competitividad (MINECO) (CTQ2016-48937-C2-1-P) and Junta de Castilla y LeĂłn and FEDER (BU076U16
Synthesis of α-functionalized α-indol-3-yl carbonyls through direct SN reactions of indol-3-yl α-acyloins
A new and efficient synthesis of α-functionalized α-indol-3-yl ketones from easily available indolyl α-acyloins is reported. This process, catalyzed by BrĂžnsted or Lewis acids, involves an uncommon direct nucleophilic substitution reaction of a secondary α-carbonyl-substituted hydroxyl group. The described methodology allows the introduction of a variety of nucleophiles such as (hetero)arenes, thiophenols, nitroanilines and 1,3-dicarbonyl derivatives. The synthesized α-indol-3-yl carbonyl compounds are important synthetic targets also useful for accessing functionalized tryptophols and furan-3-yl indoles.Ministerio de EconomĂa y
Competitividad (MINECO) (CTQ2013-48937-C2-1-P) and Junta
de Castilla y LeĂłn and FEDER (BU237U13 and BU076U16
Asymmetric Gold(I)âCatalyzed Tandem HydroarylationâNazarov Cyclization: Enantioselective Access to Cyclopentenones
The asymmetric synthesis of cyclopentachromenones from gold-catalyzed reaction of readily available skipped alkenynones is described. This cascade
reaction involves an initial anti-Michael hydroarylation
of the ynone moiety to form a gold-functionalized
dialkenylketone intermediate, followed by a Nazarov
cyclization that proceeds in an unprecedented enantioselective manner. Excellent enantiomeric ratios and chemical yields are obtained under mild reaction conditions.We gratefully acknowledge Ministerio de Ciencia e InnovaciĂłn and FEDER (CTQ2016-75023-C2-1-P and PID2020- 115789GB-C21), and Junta de Castilla y LeĂłn and FEDER (BU291P18 and BU049P20) for financial support. The project leading to these results has received funding from âla Caixaâ Foundation, under the Agreement LCF/PR/ PR18/51130007> (CAIXA-UBU001). M.S. and S.S.-P. thank Junta de Castilla y LeĂłn (ConsejerĂa de EducaciĂłn) and Fondo Social Europeo (ESF+) for a predoctoral and a postdoctoral contract, respectively
Gold-Catalyzed Synthesis of 1-(Indol-3-yl)carbazoles: Selective 1,2-Alkyl vs 1,2-Vinyl Migration
Gold(III)-catalyzed cycloisomerization of α-bis(indol-3-yl)methyl alkynols selectively affords 1-(indol-3-yl)carbazoles, in a transformation that takes place through a selective 1,2-alkyl vs 1,2-vinyl migration step in the vinyl-gold intermediate generated from the initial 5-endo-spirocyclization. The reaction proceeds well with either tertiary or secondary starting alkynols as well as with a wide variety of alkyne substituents. The key role of the other indol-3-yl substituent for the unexpected selectivity in the 1,2 rearrangement has also been supported by DFT calculations that reveal a low barrier, two-step mechanism in the alkyl migration path where the second indole significantly stabilizes a carbocationic intermediate.Junta de Castilla y LeoÌn and FEDER
(BU076U16) and Ministerio de EconomiÌa
y Competitividad
(MINECO) (CTQ2016-75023-C2-1-P and CTQ2016-75023-
C2-2-P
1,5-O â N Carbamoyl SnieckusâFries-Type Rearrangement
The reaction of o-lithiated O-aryl N,N-diethylcarbamates with (hetero)aromatic nitriles gives rise to functionalized salicylidene urea derivatives in high yields through a new 1,5-O â N carbamoyl migration. This SnieckusâFries-type rearrangement nicely complements previously known O â C and O â O related shifts. In addition, when dimethylmalononitrile is used as the electrophilic partner, the carbamoyl shift is preferred over the expected transnitrilation reaction.Junta de Castilla y LeoÌn and FEDER
(BU076U16) and Ministerio de EconomiÌa
y Competitividad
(MINECO) and FEDER (CTQ2016-48937-C2-1-P
Merging α-Lithiation and Aldol-Tishchenko Reaction to Construct Polyols from Benzyl Ethers
α-Lithiobenzyl ethers, generated by selective α-lithiation, undergo an aldol-Tishchenko reaction upon treatment with carboxylic esters and paraformaldehyde. The reaction of the organolithium with the carboxylate generates an intermediate enolate that, after formaldehyde addition, affords 1,2,3-triol derivatives in a straightforward and one-pot manner. These products are obtained as single diastereoisomers bearing a quaternary stereocenter. The complete diastereocontrol of the aldol-Tishchenko process is attributed to stereoelectronic preferences in the transition state.Ministerio de Ciencia e InnovacioÌn and FEDER (CTQ2016-75023-C2-1-P) and Junta de Castilla y LeoÌn and FEDER (BU291P18
1,3-Dien-5-ynes: Versatile Building Blocks for the Synthesis of Carbo- and Heterocycles
1,3-Dien-5-ynes have been extensively used as starting materials for the
synthesis of a wide number of different carbo- and heterocycles. The aim of this review is
to give an overview of their utility in organic synthesis, highlighting the variety of
compounds that can be directly accessed from single reactions over these systems. Thus,
cycloaromatization processes are initially commented, followed by reactions directed
toward the syntheses of five-membered rings, other carbocycles and, finally, heterocycles.
The diverse methodologies that have been developed for the synthesis of each of these
types of compounds from 1,3-dien-5-ynes are presented, emphasizing the influence of
the reaction conditions and the use of additional reagents in the outcome of the
transformations.Ministerio de EconomiÌa
y Competitividad
(MINECO) and FEDER (CTQ2013-41336-P, CTQ2013-
48937-C2-1-P, and CTQ2014-52488-R), Universidad de AlcalaÌ
(CCG2015/EXP-003) and Junta de Castilla y LeoÌn
(BU237U13
Regioselective synthesis of elusive 4,9-Dihydro-1H-Carbazoles by gold-catalyzed cycloisomerization of 3-Allenylmethylindoles
A general and efficient synthesis of 4,9-dihydro-
1H-carbazoles from 3-allenylmethylindoles is reported. The
process, catalyzed by a cationic gold(I) complex, involves a
formal C2âH bond activation of the indole unit by reaction
with the allene. The nature of the substituents at the allylic and
terminal positions of the allene moiety has a crucial effect on
the regioselectivity of the cyclization, which is also influenced by the catalyst and the solvent employed. Moreover, some evidence
of the contribution of different reaction routes is provided, which led us to propose a plausible multipathway mechanism
consistent with all of the results described.MICINN and FEDER (CTQ2010-15358 and CTQ2009-09949/BQU) for financial support. E.A. thanks MEC for an FPU predoctoral fellowship. P.G.-G. and M.A.F.-R. thank MICINN for "Juan de la Cierva" and "Ramon y Cajal" contractsThis document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of organic chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher
BrĂžnsted acidâcatalyzed synthesis of tetrasubstituted allenes and polysubstituted 2H-chromenes from tertiary propargylic alcohols
A practical and environmentally benign BrĂžnsted acidâcatalyzed protocol for the preparation of all-carbon tetrasubstituted allenes, consisting in the direct SNË addition of tri- or dimethoxy arenes or allyltrimethylsilane to tertiary propargylic alcohols, has been developed. In addition, a straightforward synthesis of densely substituted 2H-chromenes by metal-free tandem allenylation/heterocyclization reaction of methoxyphenols and tertiary alkynols is presented.Junta de Castilla y LeĂłn and FEDER (BU291P18) and Ministerio de EconomĂa y Competitividad (MINECO) and FEDER (CTQ2016-75023-C2-1-P
Uso de un compuesto de fĂłrmula (I) como bactericida frente a Streptococcus
Uso de al menos un compuesto de fĂłrmula (I)
donde R1
es alquilo C1-C6 o forma Ncicloalquilo
C5-C8 junto con R2
;
R
2
es alquilo C1-C6, forma Ncicloalquilo
C5-C8 junto con R1
, o es
una cadena alquĂlica que se une a (CH2)n
formando una amina bicĂclica; R3
es alquilo
C1-C2 o ausente; R4
es un
sustituyente aromĂĄtico que comprende al menos dos
anillos aromĂĄticos; n es un valor entre 1 y 2; y m es
un valor entre 0 y 1; como bactericida frente a
Streptococcus, preferiblemente frente a Streptococcus
pneumoniae. Adicionalmente, compuesto de fĂłrmula
(Ia) y una composiciĂłn bactericida que lo comprenda.Peer reviewedConsejo Superior de Investigaciones CientĂficas, Universidad Miguel HernĂĄndezB1 Patente sin examen previ
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