18 research outputs found
Intramolecular coupling of chiral diimines using low-valent titanium reagents: stereoselective synthesis of chiral 3,4-disubstituted-2,5-diazabicyclo[4.4.0]decanes
Chiral 3,4-disubstituted-2,5-diazabicyclo[4.4.0]decanes are prepared from (1R,2R)-1,2-diaminocyclohexane derived diimines through intramolecular coupling using low valent titanium reagent systems
Stereoselective synthesis of syn-β-amino esters using the TiCl<SUB>4</SUB>/R<SUB>3</SUB>N reagent system
The reactions of benzaldehyde imines and esters with the TiCl4/R3N reagent system give syn-β-amino esters as the major products in 38–87% yields
Un sistema de referencia para la interpretación de las funciones biológicas elementales
En este ensayo se trata de establecer una axiomática elemental a la que se considera en su totalidad como una hipótesis de trabajo. Esta axiomática, como cualquier otra, puede servir de sistema de referencia para comparar las manifestaciones más importantes de la materia viva,desde sus propiedades fisiológicas, de su estructura y forma, hasta su constancia y tendencia a la formación de niveles integrativos de organización superior. Esto se hace ya que varios autores dicen que la axiomática actual no es suficiente para establecer la unidad conceptual de dicha ciencia.En el método propuesto utilizamos a menudo el procedimiento de reemplazar un conjunto de variables por una constante, para poder seguir trabajando. A tal sustitución la denominamos "hipótesis de trabajo" en ese sentido se efectúa una operación aproximada a la de lasmatemáticas. Dichas hipótesis de trabajo estarán sujetas por definición, y posteriormente, a un análisis para el estudio y determinación de las Ãnterrelaciones de las variables que las constituyen
NHC-Catalyzed Formal [4 + 2] Annulation of <i>o</i>‑Formyl-Tethered Michael Acceptors and Ynones to Access Highly Functionalized Naphthalene Derivatives
Herein
we demonstrate a novel organocatalytic method
to access
multifunctionalized naphthalenes via an NHC-catalyzed
reaction of ynones and o-formyl-tethered Michael
acceptors. The presented method proceeds through an intermolecular
Stetter reaction–cyclization–aromatization cascade and
represents a rare example of organocatalytic benzannulation for the
synthesis of substituted arenes by using ynone as a two-carbon synthon.
The current method has broad substrate scope; postsynthetic transformations
and gram-scale syntheses highlight the practicality of the displayed
methodology
Sequential One-Pot Carbene-Catalyzed Intramolecular Stetter Reaction and Acid-Mediated Condensation: Access to Heteroatom Analogues of π‑Extended Polyaromatic Hydrocarbons
In this Letter, we disclose a simple and effective method
to access
a variety of phenanthro[9,10-b]furan and 1H-dibenzo[e,g]indole derivatives
based on the design of a carbene-catalyzed intramolecular Stetter
reaction followed by a Paal–Knorr reaction in one-pot. These
compounds are a class of π-extended polycyclic aromatic hydrocarbon
(PAH) derivatives containing an oxygen/nitrogen atom. The practical
utility of the developed transformation was demonstrated on the gram
scales and postsynthetic transformations thereof
Ruthenium catalyzed β-C(sp(3))-H functionalization on the 'privileged' piperazine nucleus
International audienceβ-C(sp(3))-H functionalization on the 'privileged' piperazine nucleus has been disclosed using ruthenium catalysis. The ruthenium catalyzed synthesis of a variety of piperazine fused indoles from ortho-piperazinyl (hetero)aryl aldehydes is presented. This transformation takes place via the dehydrogenation of piperazine followed by an intramolecular nucleophilic addition of the transient enamine moiety onto the carbonyl group and aromatization cascade
Copper-Catalyzed Tandem O‑Arylation–Oxidative Cross Coupling: Synthesis of Chromone Fused Pyrazoles
Intermolecular tandem copper-catalyzed
O-arylation–oxidative
acylation (cross dehydrogenative coupling-CDC) has been developed
under air as an oxidant. The reaction between 2,4-dihydro-3<i>H</i>-pyrazol-3-ones and <i>ortho</i>-halo aryl carboxaldehydes
furnished the corresponding chromone fused pyrazoles, in a straightforward
manner. The synthetic utility of the presented tandem catalysis has
been demonstrated with the synthesis of an A<sub>2</sub>-subtype selective
adenosine receptor antagonist in only two steps
Ruthenium Catalyzed Regioselective beta-C(sp(3))-H Functionalization of N-Alkyl-N '-p-nitrophenyl Substituted Piperazines using Aldehydes as Alkylating Agents
International audienceHerein, we disclose a ruthenium-catalyzed regioselective beta-C(sp(3))-H bond functionalization on the piperazine core using aldehydes as alkylating agents. The present transformation appears to go through the dehydrogenation of the piperazine to propagate to enamine in situ, followed by nucleophilic addition to the aldehyde and hydrogenation to result in the regioselective beta-C(sp(3))-H alkylation. A variety of aromatic, heteroaromatic, aliphatic aldehydes were employed for the C-3 alkylation of N-alkyl-N '-p-nitrophenyl substituted piperazines
Direct Access to (±)-10-Desbromoarborescidine A from Tryptamine and Pentan-1,5-diol
A single step synthetic strategy for (±)10- Desbromoarborescidine A is
described. Starting from tryptamine and pentan-1,5-diol, this acceptorless dehydrogenative
condensation process is efficiently catalyzed by a ruthenium complex featuring
proton-responsive phosphine pyridone ligand.Manuscript is available supporting material is available and includes
experimental procedures, characterization of compounds, 1H, 13C NMR spectra and
chromatograms.</div