Poly(ethylene glycol) Promoted Reactions of Vinylic Dibromides. Dehydrohalogenation and Palladium(0)-Catalyzed Formal Oxidative Homologation

Aldehydes are converted to the homologous acids by a simple two-step procedure involving initial generation of a vinylic dibromide followed by Pd(diphos)2 catalyzed, poly(ethylene glycol) induced reaction with base. This reaction is useful for aromatic and α,β-unsaturated aldehydes and is also applicable to cyclic as well as alkyl aryl ketones. 1-Bromoalkynes are formed in good yields when the vinylic dibromide reaction is effected in the absence of the palladium (0) catalyst.