Tertiary Nucleophiles Research Articles

Design of an Electron-Withdrawing Benzonitrile Ligand for Ni-Catalyzed Cross-Coupling Involving Tertiary Nucleophiles.

The design of new ligands for cross-coupling is essential for developing new catalytic reactions that access valuable products such as pharmaceuticals. In this report, we exploit the reactivity of nitrile-containing additives in Ni catalysis to design a benzonitrile-containing ligand for cross-coupling involving tertiary nucleophiles. Kinetic and Hammett studies are used to elucidate the role of the optimized ligand, which demonstrate that the benzonitrile moiety acts as an electron-acceptor to promote reductive elimination over β-hydride elimination and stabilize low-valent Ni. With these conditions, a protocol for decyanation-metalation and Ni-catalyzed arylation is conducted, enabling access to quaternary α-arylnitriles from disubstituted malononitriles.

ChemInform Abstract: General Allylic C—H Alkylation with Tertiary Nucleophiles.

AbstractA general method for intermolecular allylic C—H alkylation of terminal olefins with tertiary nucleophiles is developed employing palladium(II)/bis(sulfoxide) catalysis.

General Allylic C–H Alkylation with Tertiary Nucleophiles

A general method for intermolecular allylic C–H alkylation of terminal olefins with tertiary nucleophiles has been accomplished employing palladium(II)/bis(sulfoxide) catalysis. Allylic C–H alkylation furnishes products in good yields (avg. 64%) with excellent regio- and stereoselectivity (>20:1 linear:branched, >20:1 E:Z). For the first time, the olefin scope encompasses unactivated aliphatic olefins as well as activated aromatic/heteroaromatic olefins and 1,4-dienes. The ease of appending allyl moieties onto complex scaffolds is leveraged to enable this mild and selective allylic C–H alkylation to rapidly diversify phenolic natural products. The tertiary nucleophile scope is broad and includes latent functionality for further elaboration (e.g., aliphatic alcohols, α,β-unsaturated esters). The opportunities to effect synthetic streamlining with such general C–H reactivity are illustrated in an allylic C–H alkylation/Diels–Alder reaction cascade: a reactive diene is generated via intermolecular allylic C–H alkylation and approximated to a dienophile contained within the tertiary nucleophile to furnish a common tricyclic core found in the class I galbulimima alkaloids.

FunctionalizedC-Glycosyl Compounds. III. Reaction of Tertiary Nucleophiles with Unsaturated Carbohydrates. Mechanism of the Anomerization

Abstract Phenyl 2, 3-dideoxy-4, 6-di-O-benzyl-D-erythro-hex-2-enopyranoside 1α (or 1β) is alkylated regio- and stereospecifically at the anomeric center by stabilized tertiary nucleo-philes in the presence of Pd(0) as a catalyst, leading to the C-glycoside of α- (or β-) configuration. The observed loss of stereoselectivity using secondary stabilized nucleophiles is mainly due to a retro Michael reaction. The assignment of the α- (or β-) configuration at the anomeric center was accomplished using 13C NMR and NOE experiments.