A new three-component one pot reaction of trinitromethane, epoxides and alkenes via dinitronitronates: synthesis of highly functionalized 3,3-dinitroisoxazolidines

A novel approach to acyclic alkyldinitronitronates using nucleophilic opening of epoxides with the trinitromethyl anion is presented. The scope and limitations of this synthetic procedure are presented. A series of highly functionalized 3,3-dinitroisoxazolidines were synthesized as mixtures of diastereomers.     

Na/THF- Mediated cleavage of organic disulfides/diselenides. An efficient and one-pot regioselective method to the synthesis of β-hydroxy sulfides/selenides

A new, facile, and efficient methodology for synthesizing β-hydroxy sulfides/selenides has been reported. In this study, 1,2-epoxide ring opening was used as the synthetic protocol, and this reaction was examined using metallic sodium with no additional catalyst. This lead to the synthesis of the desired ring-opened products. Relatively short reaction times, mild reaction conditions, a simple work-up, moderate to good yields of products, and remarkable regioselectivity of the nucleophilic attack were other important features of this study.     

Epoxides related to dioncoquinone B: Synthesis,activity against multiple myeloma cells,and search for the target protein

Epoxide 2b is an analog of the synthetic intermediate 2a en route to the polyketide-derived antitumoral naphthoquinone dioncoquinone B (1), isolated from cell cultures of the tropical liana Triphyophyllum peltatum (Dioncophyllaceae). Compound 2b was found to induce strong apoptosis in multiple myeloma cells at a concentration (EC₅₀?=?3.5?μM), distinctly lower than that of 1 and any related analog, without exerting significant toxicity against normal blood cells. Preliminary studies showed that 2b follows different SAR rules as compared to the naphthoquinones. Among the series of synthesized epoxides, 2b was the most active one and was thus, after biotinylation, subjected to mass spectrometry-based affinity capture experiments aiming at the identification of target proteins. The MS data revealed 2b to address proteins that are associated with stress regulation processes which are critical for multiple myeloma cell survival.     

Chiral building blocks from d-xylose and their application in synthesis of avocadotriol monoacetate

Facile routes to several enantiomerically pure flexible chiral building blocks carrying a hidden syn or anti 1,3-diol motif were developed with the inexpensive and readily available carbohydrate d-xylose as the starting material. Application of the newly developed chiral building blocks in total synthesis is exemplified through a synthesis of (2S,4S)- and (2S,4R)-avocadotriol. Both triols were selectively acetylated on the primary hydroxyl group in high yields with Novozyme 435/vinyl acetate. On the basis of comparison of the ¹H NMR, optical rotation, and melting point data, the natural avocadotriol 1-monoacetate was assigned to be of (2R,4R) configuration.     

Trifluoromethylated cyclopropanes and epoxides from CuI-mediated transformations of α-trifluoromethyl-diazophosphonate

An efficient method for the preparation of α-(trifluoromethyl)-cyclopropylphosphonates and α-(trifluoromethyl)-1,2-epoxyphosphonates has been developed. The method is based on metal-catalyzed reaction of diethyl 1-diazo-2,2,2-trifluoroethylphosphonate (1) with alkenes or carbonyl compounds, respectively. It established an essential advantage of CuI-catalysis over Rh₂(OAc)₄ in cyclopropanation reactions. An inexpensive copper iodide has also exhibited a good catalytic activity in the synthesis of epoxyphosphonates (3).     

Ultrasound assisted, ruthenium-exchanged FAU-Y zeolite catalyzed alkylation of indoles with epoxides under solvent free conditions

Ruthenium-exchanged FAU-Y zeolite (RuY) was used as a recyclable catalyst for regioselective ring-opening of epoxides with indoles under irradiation of sonic waves. It was found that a solvent free process, under the above mentioned conditions provides good yields of the desired 3-alkylated indole derivatives.     

Preparation of enol ester epoxides and their ring-opening to α-silyloxyaldehydes

The Z-selective ruthenium-catalyzed addition of aromatic carboxylic acids to alkynes was followed by dioxirane epoxidation to furnish enol ester epoxides with cis configuration. Upon treatment of enol ester epoxides with tert-butyldimethylsilyl triflate in the presence of 2,6-lutidine, synthetically useful α-silyloxyaldehydes were obtained. This novel transformation was facilitated by microwave irradiation.     

H3PMo12O40-catalyzed coupling of diarylmethanols with epoxides/ diols/aldehydes toward polyaryl-substituted aldehydes

A versatile heteropoly acid (H₃PMo₁₂O₄₀)-catalyzed coupling of diarylmethanols with epoxides was established for the synthesis of polyaryl-substituted aldehydes. Furthermore, the catalytic system was also suitable for the reaction of diarylmethanols and diols/aldehydes. The application of such an earthabundant, readily accessible, and nontoxic catalyst provides a green approach for the construction of polyaryl-substituted aldehydes.     

Synthesis of enantiopure cis-decahydroquinolines from homotyramines by Birch reduction and aminocyclization

Birch reduction of homotyramines with a syn-β-amino alcohol unit followed by acid treatment of formed dihydroanisole derivatives gives polysubstituted enantiopure cis-decahydroquinolines. The stereoselectivity of the process differs if the hydroxyl group is free or protected. The procedure allows the synthesis of 7-oxodecahydroquinolines embodying four stereogenic centres with the same relative configuration as that of lepadins F and G.     

Mild and rapid method for the generation of o-quinone methide intermediates. Synthesis of puupehedione analogues

A route to simpler analogues to bioactive puupehedione derivatives involving a hetero Diels-Alder cycloaddition of a o-quinone methide is described. These intermediate species are generated via fluoride-induced desilylation of silyl derivatives of o-hydroxybenzyl iodides. Remarkable short reaction times and very mild experimental conditions are the main features of this method.