Formate-Mediated Reductive Cross-Coupling of Vinyl Halides and Aryl Iodides: -Substitution via Palladium(I) Catalysis.

Formate-mediated reductive cross-couplings of vinyl halides with aryl iodides via palladium(I) catalysis occur with highly uncommon -substitution. The active dianionic palladium(I) catalyst, [PdI][NBu], is generated from Pd(OAc), BuNI, and formate. Oxidative addition of aryl iodide followed by dissociation of the dimer provides the monomeric anionic T-shaped arylpalladium(II) species, [Pd(Ar)(I)(NBu)], which, upon vinyl halide carbopalladation, forms products of -substitution by way of palladium(IV) carbenes, as corroborated by deuterium-labeling experiments.

Oxetane-, Azetidine-, and Bicyclopentane-Bearing -Heterocycles from Ynones: Scaffold Diversification via Ruthenium-Catalyzed Oxidative Alkynylation.

A process for 3-fold scaffold diversification is achieved via ruthenium-catalyzed oxidative alkynylation of commercially available oxetanols, azetidinols and bicyclopentanols to form α,β-acetylenic ketones (ynones), which are subsequently converted to oxetane-, azetidine- and bicyclopentane-bearing pyrazoles, isoxazoles and pyrimidines. A one-pot oxidative alkynylation-condensation protocol that directly converts azetidinols to azetidine-substituted pyrazoles or pyrimidines is demonstrated.

Acetyl 1,3-Propanediol as an Acrolein Proelectrophile in Enantioselective Iridium-Catalyzed Carbonyl Allylation.

-Acetyl 1,3-propanediol serves as an acrolein proelectrophile in π-allyliridium-,-benzoate-catalyzed carbonyl allylations mediated by racemic α-substituted allylic acetates. Using the iridium catalyst modified by ()-SEGPHOS, a variety of 3-hydroxy-1,5-hexadienes are formed with uniformly high levels of regio-, -diastereo-, and enantioselectivity.

Ruthenium-Catalyzed C-C Coupling of Terminal Alkynes with Primary Alcohols or Aldehydes: α,β-Acetylenic Ketones (Ynones) via Oxidative Alkynylation.

The first metal-catalyzed oxidative alkynylations of primary alcohols or aldehydes to form α,β-acetylenic ketones (ynones) are described. Deuterium labelling studies corroborate a novel reaction mechanism in which alkyne hydroruthenation forms a transient vinylruthenium complex that deprotonates the terminal alkyne to form the active alkynylruthenium nucleophile.

Allyl Alcohol as an Acrolein Equivalent in Enantioselective C-C Coupling: Total Synthesis of Amphidinolides R, J, and S.

The first systematic study of catalytic enantioselective 1,2-additions to acrolein is described. Specifically, using allyl alcohol as a tractable, inexpensive acrolein proelectrophile, iridium-catalyzed acrolein allylation is achieved with high levels of regio-, -diastereo-, and enantioselectivity. This process delivers 3-hydroxy-1,5-hexadienes, a useful compound class that is otherwise challenging to access via enantioselective catalysis.