Development of New <i>P</i>‑Chiral <i>P</i>,π-Dihydrobenzooxaphosphole Hybrid Ligands for Asymmetric Catalysis

A new family of <i>P</i>-chiral <i>P</i>,π-hybrid ligands was prepared from the dihydrobenzooxaphosphole core. These new ligands were demonstrated to be both sterically and electronically tunable at the substituents on the phosphorus atom <i>and</i> the π-system of the ligand. Application of these new ligands to the catalytic asymmetric addition of boronic acids to imine electrophiles was shown to proceed with high levels of enantioinduction

Synthesis of Pyridyl-dihydrobenzooxaphosphole Ligands and Their Application in Asymmetric Hydrogenation of Unfunctionalized Alkenes

Synthesis of the electron-rich 2-substituted-6-(phenyl­sulfonyl)­pyridines is presented. A series of air-stable, tunable, <i>P</i>-chiral pyridyl-dihydrobenzooxaphosphole ligands were designed and synthesized by a diastereoselective S_NAr substitution of the corresponding sulfonyl pyridines. The ligands were successfully applied in the Ir-catalyzed asymmetric hydrogenation of unfunctionalized alkenes with good enantioselectivities

Synthesis of Pyridyl-dihydrobenzooxaphosphole Ligands and Their Application in Asymmetric Hydrogenation of Unfunctionalized Alkenes

Synthesis of the electron-rich 2-substituted-6-(phenyl­sulfonyl)­pyridines is presented. A series of air-stable, tunable, <i>P</i>-chiral pyridyl-dihydrobenzooxaphosphole ligands were designed and synthesized by a diastereoselective S_NAr substitution of the corresponding sulfonyl pyridines. The ligands were successfully applied in the Ir-catalyzed asymmetric hydrogenation of unfunctionalized alkenes with good enantioselectivities

The P‑Chiral Phosphane Ligand (MeO-BIBOP) for Efficient and Practical Large-Scale Rh-Catalyzed Asymmetric Hydrogenation of <i>N</i>‑Acetyl Enamides with High TONs

A highly electron-rich P-chiral bis­(trialkylphosphane) ligand MeO-BIBOP (<b>1</b>) was efficiently synthesized on large scale. The MeO-BIBOP–rhodium complex exhibited remarkably high reactivities (up to 200,000 TON) for the hydrogenation of <i>N</i>-acetyl enamides to provide chiral acetamides on kilogram scale. In the meantime, a high-yielding, cost-effective, and practical preparation of <i>N</i>-acetyl enamide by reductive acylation of oxime was developed employing an in situ formation of Fe­(II) acetate from Fe/AcOH/Ac₂O

Synthesis of Enantioenriched 2‑Alkyl Piperidine Derivatives through Asymmetric Reduction of Pyridinium Salts

An Ir-catalyzed enantioselective hydrogenation of 2-alkyl-pyridines has been developed using ligand MeO-BoQPhos. High levels of enantioselectivities up to 93:7 er were obtained. The resulting enantioenriched piperidines can be readily converted into biologically interesting molecules such as the fused tricyclic structures <b>5</b>, <b>6</b>, and <b>7</b> in 99:1 er, providing a novel, concise synthetic route to this family of chiral piperidine-containing compounds

Diastereoselective Synthesis of α‑Quaternary Aziridine-2-carboxylates via Aza-Corey–Chaykovsky Aziridination of <i>N</i>-<i>tert</i>-Butanesulfinyl Ketimino Esters

A general, scalable, and highly diastereoselective aziridination of <i>N</i>-<i>tert</i>-butanesulfinyl ketimino esters is described. The methodology has been utilized to provide straightforward access to previously unobtainable, biologically relevant α-quaternary amino esters and derivatives starting from readily available precursors

Sequential C–H Arylation and Enantioselective Hydrogenation Enables Ideal Asymmetric Entry to the Indenopiperidine Core of an 11β-HSD‑1 Inhibitor

A concise asymmetric synthesis of an 11β-HSD-1 inhibitor has been achieved using inexpensive starting materials with excellent step-economy at low catalyst loadings. The catalytic enantioselective total synthesis of <b>1</b> was accomplished in 7 steps and 38% overall yield aided by the development of an innovative, sequential strategy involving Pd-catalyzed pyridinium C–H arylation and Ir-catalyzed asymmetric hydrogenation of the resulting fused tricyclic indenopyridinium salt highlighted by the use of a unique P,N-ligand (MeO-BoQPhos) with 1000 ppm of [Ir­(COD)­Cl]₂