Sulfated titania catalyzed water mediated efficient synthesis of dicoumarols—a green approach

An efficient, mild, and environmental friendly method has been developed for the synthesis of dicoumarols in water over Lewis and Bronsted acid catalyst sulfated titania (TiO₂/SO₄²⁻). The method involves the condensation of various aromatic and aliphatic aldehydes with 4-hydroxycoumarin. It affords the corresponding product in high yield with short reaction times employing a very low loading of catalyst. The catalyst was reused several times without significant change in activity.     

PTSA catalyzed synthesis of functionalized dipyrazolo[1,5]diazocine-3,8-diones via the reaction of 3-aminopyrazolone with benzaldehyde derivatives

A simple procedure for the synthesis of dipyrazolo[1,5]diazocine-3,8-diones was developed via the one-pot reaction of 3-aminopyrazolone with substituted benzaldehydes in the presence of catalytic p-toluenesulfonic acid (PTSA).     

A green synthesis of spirooxindole derivatives catalyzed by SiO2@g-C3N4 nanocomposite

Research on Chemical Intermediates - In this study, SiO2 nanoparticles were immobilized onto the surface of g-C3N4 nanosheets. The characterization of SiO2@g-C3N4 nanocomposite has been done by...     

Nano ceria catalyzed synthesis of substituted benzimidazole,benzothiazole, and benzoxazole in aqueous media

A series of substituted benzimidazoles, benzothiazoles, and benzoxazoles was synthesized by combining 1,2-phenylenediamine, 2-aminothiophenol, or 2-aminophenol with aryl, heteroaryl, aliphatic, α,β-unsaturated aldehydes in the presence of nano ceria (CeO₂) as an efficient heterogeneous catalyst.     

An efficient and green method for the synthesis of [1,3]oxazine derivatives catalyzed by thiamine hydrochloride (VB1) in water

An efficient and convenient synthesis of 1,3-oxazine derivatives has been achieved by the one-pot, multicomponent condensation of α- or β-naphthol, an aniline and formaldehyde using thiamine hydrochloride (VB₁) as a versatile biodegradable and reusable catalyst in water as a universal solvent.     

AcOH catalyzed three-component synthesis of spirooxindole derivatives

An efficient one-pot synthesis of hereto unknown indenoquinoline-spirooxindole derivatives by a three-component reaction of isatins, indan-1,3-dione, and 3-aminocyclohex-2-enone under the catalysis of acetic acid was developed. The procedure had the advantages of simplicity and efficiency.     

Rhodium catalyzed asymmetric synthesis of Chiraphos derivatives

Herein, we report a highly efficient versatile synthetic route to Chiraphos derivatives through Rh/Ph-bod catalyzed asymmetric addition of aryl boronic acids to phosphinyl dienes. Various substituted phosphinyl dienes, both on the parent skeleton and the phosphine atoms, were well tolerated with this method and provided chiral phosphine oxides in satisfied yield and up to 95% ee. The corresponding Chiraphos derivative displayed an advantage over Chiraphos in the representative Pd-catalyzed asymmetric 1,4-addition reaction.     

Thiazole and benzothiazole derivatives of cytisine

Several new derivatives were prepared by reacting N-1(5-R-thiazol-2-yl)-2-chloroacetamides and N-1(6-R-benzothiazol-2-yl)chloroacetamides with cytisine. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 379–380, July–August, 2006.     

A green approach for synthesis of naphthoquinone-fused oxazine derivatives in water under ultrasonic irradiation

An efficient and eco-friendly procedure has been developed for synthesis of naphthoquinone-fused oxazine derivatives via one-pot pseudo four-component reaction of 2-hydroxy-1,4-naphthoquinone, aromatic amine and formaldehyde in water under ultrasound irradiation. This protocol has the advantages of being catalyst-free, with short reaction times and high yields, and being environmentally benign with an easy work-up.     

Iodine catalyzed synthesis of the chromene derivatives in one-pot

Iodine catalyzed one-pot reactions of salicylaldehyde and dimolecular 1 H-indene-1,3(2H)-dione,barbituric acids,4-hydroxycoumarin, or 4-hydroxy-6-methylpyran-2-one were performed and provided a rapid,convenient and general approach to synthesize the chromene derivatives.2-(11-Oxo-10,11-dihydroindeno[l,2-b]chromen-10-yl)-1H-indene-1,3(2H)-diones P1-P4 and 10-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-3-methylpyrano[4,3-6]chromen-1(10H)-ones P8-P9 were unprecedentedly prepared and structurally identified by NMR and Mass.The confirmation of structure by single crystal X-ray crystallography is reported for P3.     

An environmentally benign,green, and efficient ionic liquid catalyzed synthesis of Quinoline derivatives via Knoevenagel condensation

The present investigation is in the interest of one-pot, environmentally friendly and efficient protocol for the synthesis of quinoline derivatives from 2-aminoarylketones and active methylene compounds in the presence of L-proline and ionic liquid 1,3-dimethylimidazolium methyl sulfate [MMIm][MSO₄]. The Ionic liquid which is used as a catalyst can be reused several times. The results obtained by using [MMIm][MSO₄] were also compared with those described in the literature. The advantages of the method are shorter reaction time, milder conditions, easy workup and better yields. The catalyst [MMIm][MSO₄] can be recovered for the subsequent reactions and reused without any appreciable loss of efficiency. This method of synthesis widens the applicability of Ionic liquids in heterocyclic compounds.     

Ionic liquid catalyzed one-pot multi-component synthesis of fused pyridine derivatives: A strategy for green and sustainable chemistry

The synthesis of a combinatorial library of heterocycle-fused pyridine derivatives has been achieved successfully via a one-pot four-component reaction of aromatic/aliphatic aldehyde, malononitrile, thiazolidine-2,4-dione and ammonium acetate in the presence of piperidinium acetate as the catalyst. It involved the Knoevenagel condensation of the aldehyde and malononitrile to produce arylidene malononitrile as an intermediate, which was further intramolecular cyclization through Michael type addition ketone to the electrophilic double bond of the arylidene to produce fused pyridines in high yields. Environmental friendliness, low cost, Operational simplicity, extensive reusability and applicability, and easy recovery of the catalyst using simple evaporation are the critical features of this methodology. Also, a series of pyridine based dihydrothiazolo[4,5-b] pyridine-6-carbonitrile analogs were synthesized and selected for their in vitro antifungal and antibacterial activities.     

A novel and green synthesis of indolone-N-amino acid derivatives via the Passerini three-component reactions in water

A green Passerini three-component reaction of 2-(4-oxo-4,5,6,7-tetrahydro-1H-indol-1-yl)acetic acid with alkyl or aryl isocyanides and aldehydes was reported under aqueous conditions at 35 8C for 1 h, and21 indolone-N-amino acid derivatives were prepared in high yields of [1_TD$IF]42%–99%. Their structures were characterized by IR, ESI–MS, NMR and elemental analysis, and the possible mechanisms have been also proposed. The highly efficient and eco-friendly method provides a facile access to a library of indoloneN-amino acid derivatives for future research on bioactivity screening.     

One-pot synthesis of tetrahydrochromene derivatives catalyzed by lipase

An efficient and green one-pot synthesis route for tetrahydrochromene derivatives was developed. Lipase from Porcine pancreas (PPL) shows excellent catalytic activity and exerts good adaptability to different substrates in the reaction. All the reactions go smoothly and provide tetrahydrochromene derivatives with isolate yield up to 97% under room temperature. This lipase-catalyzed multistep conversion method has provided a new strategy to synthesize chromene derivatives and expanded the application of enzyme in organic synthesis.     

A green route for the synthesis of 2-substituted benzoxazole derivatives catalyzed by Al-exchanged K10 clay

A new, simple, and efficient protocol is developed for the synthesis of 2-substituted benzoxazole derivatives through N–C–O bond formation using Al³⁺-exchanged K10 clay (Al³⁺-K10) as catalyst. A wide range of benzoxazole derivatives are synthesized in high yields without affecting many functional groups. Hot filtration experiments showed the absence of metal leaching and catalyst can be reused for five times with only a slight decrease in yield.     

One-pot synthesis of quinoline-4-carboxylic acid derivatives in water: Ytterbium perfluorooctanoate catalyzed Doebner reaction

Ytterbium perfluorooctanoate [Yb(PFO)₃] has been proved to be an efficient catalyst for Doebner reaction of pyruvic acid, aldehydes and amines under mild conditions in water to afford quinoline-4-caboxylic acid derivatives with three component one-pot method in good yields. The process is operationally simple and environmentally benign and the catalyst has readily been recycled for several times with consistent activity. Furthermore, a plausible mechanism for this transformation is also presented.     

A green,simple, catalyst-free,and efficient method for electro-organic synthesis of new benzofuran derivatives

In this work, the electrochemical oxidation of catechols 1a and 1b was studied in the presence of pyrazolidine-3,5-dione (3a), as a nucleophile, in a mixture of ethanol and a phosphate buffer solution (0.1 M, pH 7), as a green medium, using the cyclic voltammetry and controlled-potential coulometry techniques. The results obtained indicated that the oxidized forms of these catechols (2a and 2b) participated in the Michael addition reactions with pyrazolidine-3,5-dione (3a), and converted, via an ECEC mechanism, to their corresponding benzofurans (7a and 7b). In this work, some new benzofuran derivatives were synthesized with good yields and high purities using a facile, one-pot, and environmentally friendly electrochemical method in the absence of any chemical catalyst, toxic solvent, and hard conditions.