Research Projects

Gold redox catalysis is an emerging and powerful tool in organic synthesis. However, achieving high enantioselectivity in such reactions remains a major challenge. Recent advances have shown that specially designed ligands can help address this limitation. The Patil group developed ChetPhos, a chiral hemilabile P,N-ligand that enabled highly enantioselective 1,2-oxy- and aminoarylation of alkenes. However, its success was restricted to systems where the alkene was tethered to the aryl iodide. In fully intermolecular reactions, the enantioselectivity dropped drastically. To overcome this drawback, the present proposal focuses on developing new P,N-ligands based on a spirobiindane framework. Spirobiindanes possess a rigid and orthogonal ring structure that creates a well-defined and compact chiral pocket. This architecture is ideal for enforcing facial selectivity during nucleophilic attack. To further enhance rigidity and stereochemical control, silicon-containing analogues (based on SPSiOL) will also be explored. These new ligands are expected to perform better in difficult intermolecular reactions and provide improved enantioselectivity. The proposed work begins with the synthesis of these chiral ligands from enantiopure (S)-SPINOL or (S)-SPSiOL. The resulting ligands will be coordinated to gold(I) centers, and the ability of these complexes to undergo oxidative addition with aryl halides will be investigated. Spectroscopic and crystallographic studies will be carried out to understand how ligand structure affects the reactivity and stability of the gold(III) intermediates. Following this, the newly developed ligands will be applied to enantioselective 1,2-amino- and oxyarylation of alkenes under gold redox catalysis. The chiral pocket formed by the rigid ligand framework will direct the nucleophile to attack from a specific face of the alkene. This facial bias is expected to enhance stereocontrol and lead to high levels of enantioselectivity in the final products. Through this approach, the project aims to overcome existing limitations in gold redox catalysis and offer a broadly applicable strategy for asymmetric synthesis.