Water-compatible synthesis of 2-trifluoromethyl-1,3-dioxanes

A water-compatible method for the diastereoselective synthesis of 2-trifluormethyl-1,3-dioxanes is described. The reaction proceeds under mild reaction conditions using simple inorganic bases; it has a very good substrate scope and can be performed with different Michael acceptors. Additionally, the reaction products can be further functionalized, showing an excellent perspective for future applications

Estudio de la reacción oxa-Michael intramolecular sobre derivados de aminoácidos, síntesis de dioles 1,3-syn nitrogenados y posibles aplicaciones a la síntesis de moléculas bioactivas

"En este documento se describe el estudio de la reacción de adición conjugada intramolecular usando 1,3-dehidroaminoésteres. Esta reacción ha sido utilizada desde hace algunas décadas para la síntesis diasteroselectiva de 1,3-dioles syn. Los ésteres de aminoácidos usados como sustratos de partida mostraron baja reactividad frente a benzaldehído el cual es el electrófilo típico en este tipo de reacciones. Estudios computacionales y experimentales indicaron que era necesario usar sistemas más electrofílicos como p-nitrobenzaldehído y/o trifluoracetofenona para la obtención del 1,3-diol syn protegido; de esta forma, se llevó a cabo un estudio completo sobre la síntesis de anillos de dioxano en donde la reacción de adición conjugada intramolecular no solo fue evaluada con derivados de ésteres de aminoácidos sino también con sustratos que poseen un sustituyente oxigenado en posición al aceptor de Michael y sobre sustratos sin sustituyente. Los resultados obtenidos indicaron que la formación del anillo de dioxano es completamente syn.""The intramolecular conjugate addition reaction has been used as a powerful tool to synthesize 1,3-diols syn. This document describes a method for the synthesis of protected 1,3-diols syn using an intramolecular oxa-Michael reaction in which dehydroamino acid esters are used as starting materials. Computational and experimental studies showed that the addition of trifluroacetophenone or p-nitrobenzaldehyde enables the formation of 1,3 dioxane ring with good yields. The selectivity of the dioxane ring was complete and the reaction showed an important counter-ion effect on the selectivity of the final protonation. This methodology works well with a large number of functional groups due to the soft reaction conditions. This intramolecular conjugate addition could be applicable to the synthesis of natural products which contain a 1-amino-2,4-diol unit".Doctor en Ciencias - QuímicaDoctorad

Estudios hacia la síntesis del anillo dilactónico de antimicinas

ilustracionesIncluye referencias bibliográficasMagíster en Ciencias - QuímicaMaestrí

¿Por qué preparamos compuestos en el laboratorio si podemos extraer moléculas activas de organismos vivos?

Es bien conocida la competencia que existe entre diferentes microorganismos por los nutrientes necesarios para su subsistencia. Esta competencia ha sido aprovechada por los químicos, biólogos, químicos farmacéuticos y médicos para diseñar nuevos medicamento

Whole Cells as Biocatalysts in Organic Transformations

Currently, the power and usefulness of biocatalysis in organic synthesis is undeniable, mainly due to the very high enantiomeric excess reached using enzymes, in an attempt to emulate natural processes. However, the use of isolated enzymes has some significant drawbacks, the most important of which is cost. The use of whole cells has emerged as a useful strategy with several advantages over isolated enzymes; for this reason, modern research in this field is increasing, and various reports have been published recently. This review surveys the most recent developments in the enantioselective reduction of carbon-carbon double bonds and prochiral ketones and the oxidation of prochiral sulfides using whole cells as biocatalytic systems

Transamidation of Carboxamides Catalyzed by Fe(III) and Water

The highly efficient transamidation of several primary, secondary, and tertiary amides with aliphatic and aromatic amines (primary and secondary) is described. The reaction is performed in the presence of a 5 mol % concentration of different hydrated salts of Fe­(III), and the results show that the presence of water is crucial. The methodology was also applied to urea and phthalimide to demonstrate its versatility and wide substrate scope. An example of its use is an intramolecular application in the synthesis of 2,3-dihydro-5<i>H</i>-benzo­[<i>b</i>]-1,4-thiazepin-4-one, which is the bicyclic core of diltiazem and structurally related drugs (Budriesi, R.; Cosimelli, B.; Ioan, P.; Carosati, E.; Ugenti, M. P.; Spisani, R. <i>Curr. Med. Chem.</i> <b>2007</b>, <i>14</i>, 279–287). A plausible mechanism that explains the role of water is proposed on the basis of experimental observations and previous mechanistic suggestions for transamidation reactions catalyzed by transition metals such as copper and aluminum. This methodology represents a significant improvement over other existing methods; it can be performed in air and with wet or technical grade solvents

Diastereoselective synthesis of trifluoromethylated 1,3-dioxanes by intramolecular oxa-Michael reaction

This record links to crystallographic data from this paper held in the Cambridge Crystallographic Data Centre