Persistent guaiazulene arylmethylium ions as electrophilic traps for metal enolates.

Guaiazulene-stabilized cations reacted with metal enolates affording carbonyl compounds with an azulene moiety. Metal enolates generated by asymmetric conjugate addition of organometallic reagents led to enantioenriched products. Additionally, guaiazulene-substituted cations efficiently react with silyl enol ethers.

Asymmetric tandem conjugate addition and reaction with carbocations on acylimidazole Michael acceptors.

We present here a stereoselective tandem reaction based on the asymmetric conjugate addition of dialkylzinc reagents to unsaturated acylimidazoles followed by trapping of the intermediate zinc enolate with carbocations. The use of a chiral NHC ligand provides chiral zinc enolates in high enantiomeric purities. These enolates are reacted with highly electrophilic onium compounds to afford densely substituted acylimidazoles.

Diastereoselective Pd-Catalyzed C-H Arylation of Ferrocenylmethanamines with Arylboronic Acids or Pinacol Esters.

An efficient diastereoselective synthesis of planar chiral ferrocenes via Pd(II)-catalyzed direct C-H activation with arylboronic acids or pinacol esters is presented. The reaction was performed under mild conditions using commercially available achiral or chiral amino acids as ligands. The best results were obtained with ( R)-Boc-alanine, which yielded products in 27-83% yield with diastereoselectivities ranging from 5:1 to 20:1 (11 examples).