Insertion Reactions and Catalytic Hydrophosphination of Heterocumulenes using α‑Metalated <i>N</i>,<i>N</i>‑Dimethylbenzylamine Rare-Earth-Metal Complexes

The reactivity of homoleptic α-metalated dimethylbenzylamine lanthanide complexes (α<i>-</i>Ln­(DMBA)₃; Ln = La, Y; DMBA = α-deprotonated dimethylbenzylamine) was probed through a series of stoichiometric insertion and catalytic hydrophosphination reactions. Both rare-earth-metal species inserted 3 equiv of various carbodiimides to form the corresponding homoleptic amidinates. α<i>-</i>La­(DMBA)₃ was also found to be a useful precatalyst for the room-temperature hydrophosphination of heterocumulenes to form phosphaguanidines, phosphaureas, and phosphathioureas in moderate to excellent isolated yields. Furthermore, through a series of stepwise stoichiometric protonation and insertion reactions, a plausible mechanism for the hydrophosphination catalysis was investigated

Insertion Reactions and Catalytic Hydrophosphination of Heterocumulenes using α‑Metalated <i>N</i>,<i>N</i>‑Dimethylbenzylamine Rare-Earth-Metal Complexes

The reactivity of homoleptic α-metalated dimethylbenzylamine lanthanide complexes (α<i>-</i>Ln­(DMBA)₃; Ln = La, Y; DMBA = α-deprotonated dimethylbenzylamine) was probed through a series of stoichiometric insertion and catalytic hydrophosphination reactions. Both rare-earth-metal species inserted 3 equiv of various carbodiimides to form the corresponding homoleptic amidinates. α<i>-</i>La­(DMBA)₃ was also found to be a useful precatalyst for the room-temperature hydrophosphination of heterocumulenes to form phosphaguanidines, phosphaureas, and phosphathioureas in moderate to excellent isolated yields. Furthermore, through a series of stepwise stoichiometric protonation and insertion reactions, a plausible mechanism for the hydrophosphination catalysis was investigated

Lanthanum-Catalyzed Double Hydrophosphinylation of Nitriles

A new lanthanum-based catalyst was shown to be effective for the double hydrophosphinylation of unactivated nitriles under very mild conditions. Surprisingly, the lanthanum catalyst gave two regioisomeric products depending on the nature of the starting nitrile. Primary alkyl nitriles undergo 1,1-addition to give products with a new P–C–P linkage and concomitant formation of a primary amine. Under the same conditions, secondary alkyl and aryl nitriles instead produced 1,2-addition products, where 1 equiv of the phosphine oxide was added to the carbon, while a second equivalent added to the nitrogen of the nitrile, resulting in a P–C–N–P framework. Further investigation of the catalytic cycle yielded evidence that all nitriles first undergo 1,1-addition (deemed the kinetic product) that then undergoes isomerization to the final unsymmetric addition product (the thermodynamic product). All catalytic reactions were run neat or with very little solvent, required little workup, and had high to moderate yields

Investigation of Steric and Electronic Features of 3‑Iminophosphine-Based Palladium Catalysts for Intermolecular Hydroamination

A series of (3-iminophosphine)­allylpalladium triflate complexes with systematic variation of both steric and electronic features was isolated and characterized. The ability of the complexes in this series to catalyze the regioselective hydroamination of 3-methyl-1,2-butadiene with aryl amines to form solely the kinetic product was probed by observing conversion to products via NMR spectroscopy. The previously unstudied 3-iminophosphine ligand composed of a di-<i>tert</i>-butyl phosphine, cyclobutene backbone, and <i>tert</i>-butyl imine provided the most active palladium hydroamination catalyst for this transformation known to date

Electronic Role of 3‑Iminophosphine Ligands in Palladium-Catalyzed Intermolecular Hydroamination

This study of the electronic characteristics of (3-iminophosphine)­allylpalladium triflate complexes has yielded catalysts with moderate to high activity for the hydroamination of monosubstituted allenes utilizing a wide range of amines. Herein, a new series of these catalysts was synthesized by varying the group on the imine moiety in order to explore the effect of the electronics of the ligand’s imine on the catalytic activity for intermolecular hydroamination reactions. Four amine substrates were examined in the catalytic hydroamination of cyclohexylallene, and apparent first-order rate constants were obtained by ¹H NMR spectroscopy. Kinetic isotope effect studies were also performed in order to support a new proposed catalytic cycle in the hydroamination of cyclohexylallene with secondary amines using [(3IP)­Pd­(allyl)]­OTf catalysts

Investigation of Steric and Electronic Features of 3‑Iminophosphine-Based Palladium Catalysts for Intermolecular Hydroamination

A series of (3-iminophosphine)­allylpalladium triflate complexes with systematic variation of both steric and electronic features was isolated and characterized. The ability of the complexes in this series to catalyze the regioselective hydroamination of 3-methyl-1,2-butadiene with aryl amines to form solely the kinetic product was probed by observing conversion to products via NMR spectroscopy. The previously unstudied 3-iminophosphine ligand composed of a di-<i>tert</i>-butyl phosphine, cyclobutene backbone, and <i>tert</i>-butyl imine provided the most active palladium hydroamination catalyst for this transformation known to date