1O2 Mediated Conversion of β-Enaminonitriles to α-Keto Amides Photosensitized by Recyclable H2TPP in Visible Light

We report a one-step approach for the conversion of β-enaminonitriles to synthetically versatile α-keto amides in moderate to high yields under visible light irradiation photosensitized by porphyrins. The method is mild, cost-effective, and sustainable and requires air as the sole reagent/oxidant. The reaction is believed to proceed via an ene-type pathway initiated by 1O2, followed by dehydration, imine hydrolysis, and subsequent nucleophilic substitution of the cyanide group by amine. The method offers a broad substrate scope and has also been extended for synthesis of α-keto esters with aliphatic alcohols as nucleophiles. The porphyrin recovered after the reaction can be reused multiple times.

Visible Light-Enhanced [3 + 2] Cycloaddition of N,N-Disubstituted Hydrazines with Organo-Cyanamides: Access to Polysubstituted 1,2,4-Triazol-3-amines

Visible light-enhanced [3 + 2] cycloaddition of N,N-disubstituted hydrazines with N-cyano-N-aryl-p-toluenesulfonamides is an efficient reaction pathway to polysubstituted 1,2,4-triazol-3-amines. The reaction is performed under mild conditions without the addition of any transition metals. This strategy involves a C(sp3)-H bond activation, a cyano cycloaddition, and the formation of two new C═N bonds. The protocol shows the advantages of good functional group tolerance and broad substrate scope. The late-stage modification experiments provide practical applications in the field of organic synthesis and medicinal chemistry.

In Silico Prediction of N-Nitrosamine Formation Pathways of Pharmaceutical Products

The recent discovery of N-nitrosodimethylamine (NDMA), a mutagenic N-nitrosamine, in pharmaceuticals has adversely impacted the global supply of relevant pharmaceutical products. Contamination by N-nitrosamines diverts resources and time from research and development or pharmaceutical production, representing a bottleneck in drug development. Therefore, predicting the risk of N-nitrosamine contamination is an important step in preventing pharmaceutical contamination by DNA-reactive impurities for the production of high-quality pharmaceuticals. In this study, we first predicted the degradation pathways and impurities of model pharmaceuticals, namely gliclazide and indapamide, in silico using an expert-knowledge software. Second, we verified the prediction results with a demonstration test, which confirmed that N-nitrosamines formed from the degradation of gliclazide and indapamide in the presence of hydrogen peroxide, especially under alkaline conditions. Furthermore, the pathways by which degradation products formed were determined using ranitidine, a compound previously demonstrated to generate NDMA. The prediction indicated that a ranitidine-related compound served as a potential source of nitroso groups for NDMA formation. In silico software is expected to be useful for developing methods to assess the risk of N-nitrosamine formation from pharmaceuticals.

Copper-Promoted Aerobic Oxidative [3+2] Cycloaddition Reactions of N,N-Disubstituted Hydrazines with Alkynoates: Access to Substituted Pyrazoles

A copper-promoted aerobic oxidative [3+2] cycloaddition reaction for the synthesis of various substituted pyrazoles from N,N-disubstituted hydrazines with alkynoates in the presence of bases is developed. This work involves a direct C(sp³)-H functionalization and the formation of new C-C/C-N bonds. In this strategy, inexpensive and easily available Cu₂O serves as the promoter and air acts as the green oxidant. The reaction exhibits the advantages of high atom and step economy, high regioselectivity, and easy operation.

Metal-Free Temperature-Controlled Intermolecular [3 + 2] Annulation to Access Benzo[d]thiazole-2(3H)-thiones and Benzo[d]thiazol-2(3H)-ones

A facile access to benzo[d]thiazole-2(3H)-thiones and benzo[d]thiazol-2(3H)-ones has been developed through a temperature-controlled intermolecular [3 + 2] annulation of N,N-disubstituted arylhydrazines with CS₂ in the presence of DMSO. This protocol can obviate the prefunctionalization of the starting materials. This direct C-S/C-N bond formation reaction was performed in the absence of any external catalysts, transition metals, bases, ligands, and oxidants with high step economy.

Copper-Catalyzed Phosphorylation of N,N-Disubstituted Hydrazines: Synthesis of Multisubstituted Phosphorylhydrazides as Potential Anticancer Agents

An efficient copper-catalyzed aerobic oxidative cross-dehydrogenative coupling reaction for the synthesis of multisubstituted phosphorylhydrazides from N,N-disubstituted hydrazines and hydrogen phosphoryl compounds is accomplished. The reaction proceeds under mild conditions without the addition of any external oxidants and bases. This work reported here represents a direct P(═O)-N-N bond formation with the advantages of being operationally simple, good functional group tolerance, and high atom and step economy. Furthermore, the selected compounds exhibit potential inhibitory activity against tumor cells, which can be used in the field of screening of anticancer agents as new chemical entities.

Radical coupling reactions of hydrazines via photochemical and electrochemical strategies

Hydrazines are versatile building blocks in organic synthesis.

Photocatalytic cross-dehydrogenative coupling reaction toward the synthesis of N,N-disubstituted hydrazides and their bromides

An efficient strategy for the divergent synthesis of N,N-disubstituted hydrazides and their bromides is reported through photoredox-catalytic cross-dehydrogenative coupling of N,N-disubstituted hydrazines and aldehydes.