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.
Hydrazonamides are fundamental building blocks in many pharmaceuticals and agricultural chemicals. Although contributions have been accomplished through multi-step reactions under harsh conditions, achieving high efficient synthetic strategy remains challenging. Considering...
A metal-and oxidant-free three-component desulfurization and deamination condensation of amidines, isothiocyanates, and hydrazines for the synthesis of structurally diverse fully substituted 1H-1,2,4-triazol-3-amines is described. The reaction proceeds without the requirement of any external catalysts, metals, ligands, or oxidants. This [2 + 1 + 2] cyclization strategy involves C−N and C−S bond cleavage and the formation of new C−N bonds in one pot. This transformation provides a series of full substituted 1H-1,2,4-triazol-3-amines with advantages of a broad substrates scope, mild reaction conditions, environmental friendliness, and easy gram-scale applications. The fluorescence and aggregation-induced emission (AIE) properties of selected products were further tested. These synthesized 1H-1,2,4-triazol-3-amines may be worth investigating for further applications in the fields of organic chemistry, medicinal chemistry, and optical materials.
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.
N,N-Disubstituted acyl hydrazides are useful synthetic building blocks as well as important pharmaceutical scaffolds in the fields of organo-pharmaceutical chemistry. Direct C(=O)-N-N bond formation represents one of the most effective...
An effective base-promoted cyclization and coupling strategy for the construction of substituted 3-aryl-5thio-1,3,4-thiadiazole-2-thiones from phenylhydrazines, olefins and CS 2 is developed through employing CS 2 as a sulfur feedstock. The reaction proceeds under mild reaction conditions in the absence of any external catalysts, transition metals and ligands. The one-step three-component procedure also shows the merits of simple operation, using available starting materials, wide substrate scopes, and high atom and step economy. This reaction provides facile access to substituted 3-aryl-5-thio-1,3,4-thiadiazole-2-thiones, which could be used in the field of drug research.
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.
An efficient three‐component deamination annulation of 2‐aminobenzamides, isothiocyanates and alkyl bromides for the synthesis of valuable 3‐substituted‐4‐oxo‐2‐quinazolinonyl sulfides is reported. The reaction proceeds in the absence of any external catalysts and additives. The facile process has the advantages of broad substrate scopes, mild reaction conditions and environmental friendliness, which might provide the synthetic applications for 3‐substituted‐4‐oxo‐2‐quinazolinonyl sulfides as potential anti‐cancer agents in medicinal chemistry.
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