Catalytic enantioselective allyl-allyl cross-coupling with a borylated allylboronate.

Catalytic enantioselective allyl-allyl cross-coupling of a borylated allylboronate reagent gives versatile borylated chiral 1,5-hexadienes. These compounds may be manipulated in a number of useful ways to give functionalized chiral building blocks for asymmetric synthesis.

Diastereocontrol in asymmetric allyl-allyl cross-coupling: stereocontrolled reaction of prochiral allylboronates with prochiral allyl chlorides.

Palladium-catalyzed allyl-allyl cross-coupling was investigated with substituted prochiral allylic boronates. These reactions deliver products bearing adjacent stereocenters, and the issue of diastereocontrol is therefore paramount. Under appropriately modified conditions, this allyl-allyl coupling strategy was found to apply to a range of substrates, generally occurring with high enantioselectivity (92:8 to >99:1 er) and good diastereoselection (4:1 to 14:1 dr).

Catalytic enantioselective conjugate allylation of unsaturated methylidene ketones.

The use of unsaturated methylidene ketones in catalytic conjugate allylations allows a significant expansion in substrate scope and, with appropriate chiral ligands, occurs in a highly enantioselective fashion.

Pd-catalyzed enantioselective allyl-allyl cross-coupling.

The Pd-catalyzed cross-coupling of allylic carbonates and allylB(pin) is described. The regioselectivity of this reaction is sensitive to the bite angle of the ligand, with small-bite-angle ligands favoring the branched substitution product. This mode of regioselection is consistent with a reaction that operates by a 3,3' reductive elimination reaction.