Carboxy‐Directed Asymmetric Hydrogenation of 1,1‐Diarylethenes and 1,1‐Dialkylethenes

Overview on the Recent Strategies for the Enantioselective Synthesis of 1, 1‐Diarylalkanes, Triarylmethanes and Related Molecules Containing the Diarylmethine Stereocenter

“…In 2013, Song et al reported carboxy group as an efficient directingg roup for the iridium catalyzed enantioselective hydrogenation of 1, 1-diarylalkenes (Scheme4). [21] The directing group could easily be removed throughd ecarboxylation leading to the formation of diary alkanes in high yields and enantioselectivities for awide variety of substrates including heterocyclic substrates which are rather challenging substrates for hydrogenation. Further,t he alkene hydrogenation and the removal of the directing group through decarboxylation allowed the transformation in one pot.…”

“…However a p-extended aromatic ring-like naphthyl or phenanthrenyl group was important for the enantioselectivity,p robablyo wing to the intermediate formation of the p-benzyl nickel species. The importance of this protocol was further highlighted by the same group on preparation of both the enantiomers of the anti-breast cancera gent (21) having IC 50 value À3.88 mm against MCF-7 breast cancerc ells.…”

Neutral iridium catalysts with chiral phosphine-carboxy ligands for asymmetric hydrogenation of unsaturated carboxylic acids

“…4 Mechanistic studies revealed that the carboxy group of the substrate anchors the molecule to the catalyst and triggers the hydrogenation reaction. On the basis of these results, we envisioned that iridium complexes with a chiral spiro phosphine-carboxy ligand might efficiently catalyze the asymmetric hydrogenation of unsaturated carboxylic acids.…”

ZnCl2‐Promoted Asymmetric Hydrogenation of β‐Secondary‐Amino Ketones Catalyzed by a P‐Chiral Rh–Bisphosphine Complex

“…Over the last half century, remarkable progress has been made in the area of asymmetric hydrogenation and it remains an important topic of research because of its great potential for industrialization. [1,2] Among the many substrates, b-amino ketones have attracted considerable attention [3,4] because of their use in the preparation of chiral g-amino alcohols, species widely used as ligands and pharmaceutical intermediates. [5,6] Unlike the extensive research on b-tertiary-amino ketones, [3] only a few studies have focused on the asymmetric hydrogenation of b-secondary-amino ketones for the preparation of chiral g-secondary-amino alcohols.…”