Iron-Mediated Reductive Amidation of Triazine Esters with Nitroarenes

Magnesium-Mediated Cross-Electrophile Couplings of Aryl 2-Pyridyl Esters with Aryl Bromides for Ketone Synthesis through In Situ-Formed Arylmagnesium Intermediates

Aryl 2-pyridyl esters could efficiently undergo cross-electrophile couplings with aryl bromides with the aid of magnesium as a reducing metal in the absence of a transition-metal catalyst, leading to the unsymmetrical diaryl ketones in modest to good yields with wide functionality compatibility. In addition, the reaction could be easily scaled up and applied in the late-stage modification of biologically active molecules. Preliminary mechanistic study showed that the coupling reaction presumably proceeds through the in situ formation of arylmagnesium reagents as key intermediates.

Nickel-Catalyzed Reductive Amidation of Aryl Fluorosulfates with Isocyanates: Synthesis of Amides via C-O Bond Cleavage

With the assistance of nickel as catalyst, 2,2'-bipyridine (bpy) as ligand, and manganese as reducing metal, the reductive amidation of isocyanates with readily accessible aryl fluorosulfates could be successfully accomplished. The reactions proceeded effectively via C-O bond activation in DMF at room temperature, enabling the facile synthesis of a range of structurally diverse amides in moderate to high yields with broad functionality compatibility. In addition, the synthetic usefulness of the method was further demonstrated by applying the reaction in scale-up synthesis and the late-stage functionalization of complex molecules with biological activities.

Cross-Electrophile Couplings of Benzyl Sulfonium Salts with Thiosulfonates via C-S Bond Activation

A zinc-mediated cross-electrophile coupling of benzyl sulfonium salts with thiosulfonates via C-S bond cleavage was achieved. The reductive thiolation proceeded well under transition metal-free conditions to afford the desired benzyl sulfides in good yields, exhibiting both broad substrate scope and good functionality tolerance. In addition, the reaction could be applied to the use of selenosulfonate as an effective selenylation agent and be subjected to scale-up synthesis.

Sulfonylation of Pyridyl Phosphonium Salts with Sulfinate Salts in Aqueous Media for the Synthesis of 4-Pyridyl Sulfones via C-P Bond Cleavage

A Na2S2O8-initiated sulfonylation of pyridyl phosphonium salts with sulfinate salts in aqueous media has been developed for facile access to 4-pyridyl sulfones. The reactions, which employed pyridyl phosphonium salts as efficient pyridylation agents via C-P bond activation, showed both broad substrate generality and good functional group compatibility. In addition, the scale-up synthesis and the late-stage modification of pharmaceutically active complex molecules (e.g., loratadine, bisacodyl) could also be successfully realized.

Photochemical α-amination of carbonyl groups with iodinanes

We report on a photochemical reaction of silyl enol ethers with iminoiodinanes. This aza Rubottom reaction provides a direct access towards α-amino carbonyl compounds under catalyst free reaction conditions with light as the sole source of energy. Control experiments suggest the participation of triplet nitrene intermediates.

Sulfur-Mediated Decarboxylative Amidation of Cinnamic Acids via C═C Bond Cleavage

A new strategy for the synthesis of amides has been developed using sulfur-mediated decarboxylative coupling of cinnamic acids with amines via oxidative cleavage of the C═C bond.

CuH-Catalyzed Reductive Coupling of Nitroarenes with Phosphine Oxides for the Direct Synthesis of Phosphamides

A CuH-catalyzed reductive coupling of nitroarenes with phosphine oxides is developed, which produces a series of phosphamides in moderate to excellent yields with good functional group tolerance. Gram-scale synthesis and late-stage modification of nitro-aromatic functional molecule niclosamide are also successfully conducted. The mechanism study shows that the nitro group is transformed after being reduced to nitroso and a nucleophilic addition procedure is involved during the reaction.

Palladium-Catalyzed Esterification of Aryl Fluorosulfates with Aryl Formates

An efficient palladium-catalyzed carbonylation of aryl fluorosulfates with aryl formates for the facile synthesis of esters was developed. The cross-coupling reactions proceeded effectively in the presence of a palladium catalyst, phosphine ligand, and triethylamine in DMF to produce the corresponding esters in moderate to good yields. Of note, functionalities or substituents, such as nitro, cyano, methoxycarbonyl, trifluoromethyl, methylsulfonyl, trifluoromethoxy, fluoro, chloro, bromo, methyl, methoxy, N,N-dimethyl, and [1,3]dioxolyl, were well-tolerated in the reactions, which could be kept for late-stage modification. The reactions employing readily available and relatively robust aryl fluorosulfates as coupling electrophiles could potentially serve as an attractive alternative to traditional cross-couplings with the use of aryl halides and pseudohalides as substrates.

Hydroxylation of Aryl Sulfonium Salts for Phenol Synthesis under Mild Reaction Conditions

Hydroxylation of aryl sulfonium salts could be realized by utilizing acetohydroxamic acid and oxime as hydroxylative agents in the presence of cesium carbonate as a base, leading to a variety of structurally diverse hydroxylated arenes in 47-95% yields. In addition, the reaction exhibited broad functionality tolerance, and a range of important functional groups (e.g., cyano, nitro, sulfonyl, formyl, keto, and ester) could be well amenable to the mild reaction conditions.