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.

Synthesis of Purine Analogues: Photocatalyst-Free Visible-Light-Enhanced Annulation Approach to Pyrazolo[1,5-a][1,3,5]triazine-2,4-diamines.

A new photocatalyst-free visible-light-enhanced strategy for the synthesis of pyrazolo[1,5-a][1,3,5]triazine-2,4-diamines via the formation of electron donor-acceptor (EDA) complexes is reported. The in situ generated pyrazolthiourea intermediates from 1H-pyrazol-3-amines and isothiocyanates undergo formal [4 + 2] annulation with 1,1,3,3-tetramethylguanidines (TMG) to deliver the corresponding products involved in three C-N bond formations in a one-pot protocol. The formation of EDA complex from pyrazolthiourea and TMG is confirmed by UV-vis spectroscopy and 1H NMR experiments. Moreover, this mild reaction proceeds in the absence of any external transition metals, oxidants, bases, and ligands. This efficient methodology for the synthesis of purine analogues pyrazolo[1,5-a][1,3,5]triazine-2,4-diamines provides potential synthetic applications in the field of drug research and development.

Visible-Light-Promoted Three-Component Coupling Annulation: Synthesis of 2-Iminothiazolidin-4-ones via in Situ Formed Electron Donor-Acceptor Complexes.

A novel and efficient three-component coupling annulation strategy for the synthesis of 2-iminothiazolidin-4-ones from amines, isothiocyanates, and alkyl acetylenedicarboxylates under visible-light irradiation conditions has been demonstrated. In this transformation, the in situ formed photoactive electron donor-acceptor (EDA) complexes facilitate the reaction and smoothly generate the corresponding products with a high adaptability under mild conditions. This protocol provides a cost-efficient and practical route to 2-iminothiazolidin-4-ones and promotes potential applications on the synthetic drugs.

Photodriven Photocatalyst/Metal-Free Direct C-C/C-N Bond Formation: Synthesis of Indoles via EDA Complexes.

The photodriven direct C-C/C-N bond formation initiated by electron donor-acceptor (EDA) complexes for the synthesis of indoles has been accomplished via [3+2] annulations of secondary arylamines with alkynes using IC4F9 as oxidants in the absence of any photocatalysts and metals. This green transformation exhibits the advantages of operational simplicity, good functional tolerances, and mild reaction conditions. The in situ generated EDA complexes derived from arylamines with alkynes were characterized by UV-vis absorption spectrometry and NMR titration experiments.

Visible-Light-Catalyzed [3 + 1 + 2] Coupling Annulations for the Synthesis of Unsymmetrical Trisubstituted Amino-1,3,5-triazines.

A visible-light catalyzed [3 + 1 + 2] annulation for the synthesis of unsymmetrical trisubstituted amino-1,3,5-triazines from amidines, isothiocyanates, and 1,1,3,3-tetramethylguanidines has been developed. This method exhibits the advantages of easily available starting materials, insensitive to air and moisture, wide substrate scopes, high step economy, mild, metal- and ligand-free conditions, which has potential applications in the organic, medicinal, and material chemistry.