Adriano S. Vieira

Nucleophilic Addition of Potassium Alkynyltrifluoroborates to d-Glucal Mediated by BF3·OEt2: Highly Stereoselective Synthesis of α-C-glycosides

A convenient, mild and highly stereoselective method for C-glycosidation (alkynylation) of D-glucal with various potassium alkynyltrifluoroborates, mediated by BF3x OEt2 and involving oxonium intermediates, preferentially provides the alpha-acetylene glycoside products with good yields.

Copper Catalyzed Cross-Coupling Reactions of Diaryl Ditellurides with Potassium Aryltrifluoroborate Salts

Apresentamos aqui resultados das reacoes de acoplamento de diteluretos de diarila com sais de ariltrifluoroborato de potassio, usando quantidades cataliticas de Cu(OAc) 2 e bipiridina, em uma mistura de DMSO/H 2 O, sob ar atmosferico. Estas reacoes de acoplamento sao gerais e sao realizadas com diteluretos de diarila e sais de ariltrifluoroborato de potassio contendo substituintes neutros, retiradores e doadores de eletrons, fornecendo os correspondentes teluretos de diarila nao simetricos em rendimentos de bons a excelentes. We present here results of the cross-coupling reaction of diaryl ditellurides with potassium aryltrifluoroborate salts using a catalytic amount of Cu(OAc) 2 and bypiridine in DMSO/H 2 O under air atmosphere. This cross-coupling reaction is general and was performed with diaryl ditellurides and potassium aryltrifluoroborate salts bearing electron-withdrawing, electron-donating and neutral substituents, affording the corresponding unsymmetrical diaryl tellurides in good to excellent yields.

Synthesis of 2-Aryl- and 2,5-Diarylfurans and Thiophenes by Suzuki-Miyaura Reactions Using Potassium Trifluoroborate Salts and Heteroaryltellurides

The Suzuki–Miyaura cross-coupling reaction of 2-(butyltellanyl) or 2,5-bis-(butyltellanyl)furans and thiophenes with potassium aryltrifluoroborate salts catalyzed by palladium afforded 2-aryl- or 2,5-diaryl-furans and thiophenes in moderate to good yields.

Stereoselective Nucleophilic Addition of Potassium Alkyltrifluoroborates to Cyclic N-Acyliminium Ions: a Simple and Mild Approach to Chiral 5-Alkyl-pyrrolidin-2-ones

The stereoselective nucleophilic addition of potassium alkyltrifluoroborates to cyclic N-acyliminium ions derived from N-benzyl-3,4,5-triacetoxy-pyrrolidin-2-one, which affords 5-substituted-pyrrolidin-2-ones, is described. The products are obtained in moderate to good yields and are produced predominantly as the anti diastereomer.

1-Benzyl-2,5-dioxopyrrolidine-3,4-diyl diacetate.

The pyrrolidine-2,5-dione ring in the title compound, C15H15NO6, is in a twisted conformation with the acetyl C atoms projecting to opposite sides of the ring. The acetyl groups lie to opposite sides of the five-membered ring. The benzene ring is roughly perpendicular to the heterocyclic ring, forming a dihedral angle of 76.57 (14)° with it. In the crystal, molecules are connected through a network of C—H⋯O and C—H⋯π interactions.

5-(4-Fluoro-phen-yl)-2,2,6-trimethyl-4H-1,3-dioxin-4-one.

The 1,3-dioxine ring in the title compound, C13H13FO3, is in a half-boat conformation with the methyl-bonded C atom 0.612 (2) Å out of the plane defined by the remaining five atoms.

2,2,6-Trimethyl-5-[2-(4-methylphenyl)ethynyl]-4H-1,3-dioxin-4-one

The 1,3-dioxin-4-one ring in the title compound, C16H16O3, is in a half-boat conformation with the quaternary O—C(CH3)2—O atom lying 0.546 (1) Å out of the plane defined by the remaining five atoms. The crystal structure is consolidated by C—H⋯O contacts that lead to supramolecular layers.