The Boron‐Wittig Olefination of Aldehydes and Ketones with Bis[(pinacolato)boryl]methane: an Extended Reaction Scope

Preparation of 2,2‐disubstituted and 2‐monosubstituted alkenylboronic acid esters from aliphatic and aromatic ketones and aldehydes by the boron‐Wittig olefination with bis[(pinacolato)boryl]methane was examined and applied on the multigram scale. The influence of the substrate steric and electronic features on the overall efficiency and stereochemical outcome of the reaction was studied. Additionally, a series of diversely functionalized (hetera)cycloalkylidenemethyl and (hetera)cycloalkyl boronic acid‐derived building blocks was synthesized. The boron‐Wittig olefination of aliphatic and aromatic ketones and aldehydes with bis[(pinacolato)boryl]methane is described. The 2,2‐disubstituted and 2‐monosubstituted alkenylboronic acid esters were obtained on a multigram scale with 35–90 % yield.