Nuno Monteiro

Intramolecular carbocupration reaction of unactivated alkynes bearing a stabilized nucleophile: Application to the synthesis of iridoid monoterpenes

Abstract The copper-promoted cycloisomerization of unsaturated alkynes bearing a stabilized nucleophile is described, providing a novel synthesis of various iridoid monoterpenes.

A modular sydnone cycloaddition/Suzuki-Miyaura cross-coupling strategy to unsymmetrical 3,5-bis(hetero)aromatic pyrazoles.

The [3 + 2] dipolar cycloaddition of 4-halosydnones with 1-haloalkynes opens a straightforward access to 3,5-dihalopyrazoles, valuable scaffolds for the elaboration of unsymmetrically 3,5-substituted pyrazole derivatives via site-selective Pd-catalyzed cross-coupling reactions. For instance, the flexible introduction of different (hetero)aryl substituents at the C-5 and C-3 positions of the PMP-protected pyrazole nucleus was achieved in a one-pot operation via sequential reactions with various boronic acids.

Et3N-Induced Demethylation−Annulation of 3-Alkynyl-4-methoxy-2-pyridones and Structurally Related Compounds in the Synthesis of Furan-Fused Heterocycles

Various 3-iodo-4-methoxypyridin-2-ones and related pyrone and coumarin derivatives have been demonstrated as readily available precursors of 2-substituted furan-fused heterocycles by means of in situ sequential Sonogashira-acetylide coupling, dealkylation, and regioselective furan annulation reactions. A Et3N-induced S(N)2 process has been established that accounts for the dealkylation process.

A Pd-catalyzed heteroannulation approach to 2,3-disubstituted furo[3,2-c]coumarins.

The Pd-catalyzed cyclofunctionalization of 3-alkynyl-4-methoxycoumarins with aryl halides resulted in the selective formation of 3-arylfuro[3,2-c]coumarins in lieu of the expected regioisomeric 3-arylfuro[2,3-b]chromones. A mechanism involving the linear to angular rearrangement of a Pd-containing furan intermediate was proposed.

A ONE POT SYNTHESIS OF VARIOUS PYRROLIDINES VIA A TANDEM MICHAEL ADDITION-TRANSITION METAL-CATALYSED CYCLISATION REACTION

Abstract A variety of substituted 3-methylene pyrrolidines may be obtained by reaction of propargyl amines with Michael acceptors in a single step catalysed by copper(I).

Formation de derives cyclopentaniques assistee par une espece hydrure de palladium : Aspects synthetiques et mecanisme☆

Resume En presence dun complexe de palladium(0) et de t-butylate de potassium, les composes acetyleniques 2 ayant en δ une fonction nucleophile sont transformes dans des conditions douces et avec dexcellents rendements, soit en methylenecyclopentanes 2,2-difonctionnalises, soit en 2-methylcyclopentenes monofonctionnalises. Le choix des conditions operatoires oriente specifiquement la reaction vers lun ou lautre de ces composes. Une serie dessais mettant principalement en jeu lhydrure de potassium comme base a montre que lespece catalytique active netait pas HPdOtBu mais un σ-ethynylpalladium issu de linsertion du metal dans la liaison carbone-hydrogene acetylenique.

PALLADIUM-MEDIATED CYCLOPENTANATION OF ALKENES BEARING A NUCLEOPHILIC SUBSTITUENT. STEREOCHEMISTRY AND MECHANISM

Abstract The increased facility of the reaction 1 2 simultaneously with the increased nucleophilicity of the malonate, as well as the stereospecificity observed in the case of 3 , led to the conclusion that the cyclisation proceeds by a nucleophilic attack on the double bond activated by a palladium(II) species.

Cyclisation of ω-unsaturated β-dicarbonylcompounds catalyzed by a palladium hydride species

Abstract When treated with potassium t-butoxide and then with a palladium(0) complex, the title compounds 1 , 2 , or 9 are smoothly cyclized by an attack of the enolates onto the unsaturation assisted by a palladium (II) species of tBuO-Pd-H type. The formation of a five-membered ring is particularly favored in such a process.

Asymmetric total synthesis of (+)-carbocyclic uracil polyoxin C

A short, practical, asymmetric synthesis of carbocyclic uracil npolyoxin C is described. The key step in the synthesis is a regio- and nstereo-selective palladium-mediated substitution reaction of an nα-amino substituted unsaturated lactone with nbis-silylated uracil. Critical to the success of this reaction is the nuse of trimethylsilyl chloride in the reaction mixture which nsubstantially enhances the reactivity of the lactone. The final stages ninvolve dihydroxylation of 1,4-disubstituted cyclopentene which is nessentially non-selective. The factors surrounding the poor selectivity nof this reaction are discussed.

A Straightforward Entry to Functionalized Carbo- and Heterocycles Based on Pd-Mediated Cyclizations

The efficient and practical syntheses of functionalized carbo-and heterocyclic compounds have been achieved employing a process based on an intramolecular palladium-mediated cyclization coupled with a carbon-carbon bond forming reaction.