Reductive coupling reactions: a new strategy for C(sp3)–P bond formation

Catalytic Asymmetric P-H Insertion Reactions

Albeit notable endeavors in enantioselective carbene insertion into X-H bonds (X = C, O, N, S, Si, B), the catalytic asymmetric P-H insertion reactions still stand for a long-lasting challenge. By merging transition-metal catalysis with organocatalysis, we achieve a scalable enantioselective P-H insertion transformation between diazo pyrazoleamides and H-phosphine oxides that upon subsequent reduction delivers a wide variety of optically active β-hydroxyl phosphine oxides in good yields with high enantioselectivity. The achiral copper catalyst fosters the carbenoid insertion into the P-H bond, while the chiral cinchona alkaloid-derived organocatalyst controls the subsequent enantioselective outcome. Density functional theory (DFT) calculations further reveal that the copper catalyst chelates to the organocatalyst, enhances its acidity, and accordingly promotes the enantioselective proton transfer. Our work showcases the potential of combining transition-metal catalysis with organocatalysis to realize elusive asymmetric reactions.

A palladium-catalyzed Barluenga cross-coupling - reductive cyclization sequence to substituted indoles

A short and flexible synthesis of substituted indoles employing two palladium-catalyzed reactions, a Barluenga cross-coupling of p-tosylhydrazones with 2-nitroarylhalides followed by a palladium-catalyzed, carbon monoxide-mediated reductive cyclization has been developed. A one-pot, two-step methodology was further developed, eliminating isolation and purification of the cross-coupling product. This was accomplished by utilizing the initially added 0.025 equivalents of bis(triphenylphosphine)palladium dichloride, thus serving a dual role in the cross-coupling and the reductive cyclization. It was found that addition of 1,3-bis(diphenylphosphino)propane and carbon monoxide after completion of the Barluenga reaction afforded, in most cases, significantly better overall yields.

Copper-catalyzed P-H insertion reactions of sulfoxonium ylides

A copper-catalyzed P-H insertion reaction between sulfoxonium ylides and H-phosphorus oxides has been demonstrated, furnishing α-phosphonyl carboxylate derivatives in 41-93% yields. This methodology utilizing bench-stable and thermodynamically stable sulfoxonium ylides as carbene precursors in the presence of the inexpensive and readily available copper catalyst shows advantages such as mild reaction conditions, good functional group compatibility, and easy scale-up, which make this protocol attractive for large-scale chemical processing and processing at the industrial scale.

Probing the reactivity of H-phosphonate derivatives for the hydrophosphonylation of various alkenes and alkynes under free-radical conditions

Hydrophosphonylation of various alkenes and alkynes is reported using DPAP as a photoinitiator under UV irradiation.

A straightforward synthesis of alkyl 1H-tetrazol-5-yl thioethers via a one-pot reaction of aldehydes and 1H-tetrazole-5-thiols mediated by N-tosylhydrazones

A method for the straightforward synthesis of alkyl 1H-tetrazol-5-yl thioethers from aldehydes and 1H-tetrazole-5-thiols through a one-pot procedure is presented.

Copper-catalyzed cross-coupling reactions for C–P bond formation

Phosphorus compounds are important compounds in many areas.

The development of a complementary pathway for the synthesis of aliskiren

We present an alternative pathway for the synthesis of aliskiren by applying the Evans chiral auxiliary-aided asymmetric allylation and the Julia–Kocienski olefination as the key transformations.