A series of π-allylpalladium complexes with neutral monodentate and bidentate ligands were prepared and examined for their ability to undergo stoichiometric umpolung allylation reactions with benzaldehyde. Neutral bidentate N-heterocyclic carbene ligands promote nucleophilic attack. Catalytic allylation reactions of aromatic and aliphatic aldehydes are reported.

Migrating through Si valley: The highly stereoselective formation of α-silyl-β- haloenones by way of silicon group migration is described. Electrophilic activation of the alkyne by N-halosuccinimides induced an anti-selective migration to give highly substituted enones (see scheme). These enone products can be readily converted to the all-carbon tetrasubstituted alkenes while maintaining their geometry.

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Silver bromide catalyzes Barbier‐type allylation of aldehydes and ketones using unactivated manganese powder. Aliphatic and aromatic aldehydes and ketones react, and aryl chlorides, nitriles, electron‐donating and electron‐withdrawing groups are tolerated. Benzylation using benzyl bromide also proceeds smoothly under these reaction conditions. Preliminary mechanistic studies are consistent with the formation a nucleophilic allylmetal intermediate. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)