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-&#946;-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-&#946;-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 ínterrelaciones 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 A₂-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