Meglumine catalyzed expeditious four-component domino protocol for synthesis of pyrazolopyranopyrimidines in aqueous medium

Meglumine has been found to be an efficient catalyst for the synthesis of structurally diverse tricyclic fused pyrazolopyranopyrimidines by one-pot, four-component reaction of ethyl acetoacetate, hydrazine hydrate, aromatic aldehydes and barbituric acid in water.

“On-water” synthesis of novel trisubstituted 1,3-thiazolesviamicrowave-assisted catalyst-free domino reactions

A clean, efficient and catalyst-free multicomponent domino reaction of arylglyoxals, cyclic 1,3-dicarbonyls and thioamides in aqueous media under microwave conditions is reported.

Metal-free synthesis of 1,3,5-trisubstituted benzenes by the cyclotrimerization of enaminones or alkynes in water

The trimeric cyclization reactions of enaminones proceed efficiently in water to provide C3 symmetric benzenes in the presence of lactic acid.

Highly diastereoselective synthesis of quinoline-2,5-diones and pyrazolo[3,4-b]pyridin-6(7H)-ones under microwave irradiation

A new and flexible three-component reaction has been established for the highly diastereoselective synthesis of bicyclic hexahydroquinoline-2,5-diones and pyrazolo[3,4-b]pyridin-6(7H)-ones.

Magnetic copper ferrite nanoparticles/TEMPO catalyzed selective oxidation of activated alcohols to aldehydes under ligand- and base-free conditions in water

A novel, effective and sustainable strategy for the synthesis of aldehydes under ligand and base free conditions has been developed using inexpensive, readily available, oxygen-stable and recyclable CuFe₂O₄ nanoparticles as the catalyst.

Solvent-free and catalysts-free chemistry: a benign pathway to sustainability

In the past decade, alternative benign organic methodologies have become an imperative part of organic syntheses and chemical reactions. The various new and innovative sustainable organic reactions and methodologies using no solvents or catalysts and employing alternative energy inputs such as microwaves, sonication, conventional and room temperature heating conditions, mechanochemical mixing, and high-speed ball milling are discussed in detail. Environmentally benign and pharmaceutically important reactions such as multicomponent, condensation, and Michael addition reactions; ring opening of epoxides; and oxidation and other significant organic reactions are discussed. An overview of benign reactions through solvent- and catalyst-free (SF-CF) chemistry and a critical perspective on emerging synergies between SF-CF organic reactions are discussed.

Tandem aldol-Michael reactions in aqueous diethylamine medium: a greener and efficient approach to bis-pyrimidine derivatives

A simple protocol, involving the green synthesis for the construction of novel bis-pyrimidine derivatives, 3a–i and 4a–e are accomplished by the aqueous diethylamine media promoted tandem Aldol-Michael reaction between two molecules of barbituric acid derivatives 1a,b with various aldehydes. This efficient synthetic protocol using an economic and environmentally friendly reaction media with versatility and shorter reaction time provides bis-pyrimidine derivatives with high yields (88%–99%).

Mukaiyama Aldol Reactions in Aqueous Media

Mukaiyama aldol reactions in aqueous media have been surveyed. While the original Mukaiyama aldol reactions entailed stoichiometric use of Lewis acids in organic solvents under strictly anhydrous conditions, Mukaiyama aldol reactions in aqueous media are not only suitable for green sustainable chemistry but are found to produce singular phenomena. These findings led to the discovery of a series of water-compatible Lewis acids such as lanthanide triflates in 1991. Our understanding on these beneficial effects in the presence of water will be deepened through the brilliant examples collected in this review. 1 Introduction 2 Rate Enhancement by Water in the Mukaiyama Aldol Reaction 3 Lewis Acid Catalysis in Aqueous or Organic Solvents 3.1 Water-Compatible Lewis Acids 4 Lewis-Base Catalysis in Aqueous or Organic Solvents 5 The Mukaiyama Aldol Reactions in 100% Water 6 Asymmetric Catalysts in Aqueous Media and Water 7 Conclusions and Perspective.