One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones using boric acid as catalyst

A simple effective synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives, using boric acid as catalyst, from aromatic aldehydes, 1,3-dicarbonyl compounds and urea in glacial acetic acid is described. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yields (86-97%) and short reaction time (0.5-2 h).     

One-pot synthesis of cyclopentadienones through ring contraction of 2H-pyran-2-ones

A one-pot synthesis of 2,3,5-trisubstituted cyclopentadienones has been delineated through ring contraction of suitably functionalized 2H-pyran-2-ones using either cyanoacetamide or methyl cyanoacetate.     

Efficient route to 2H-1,3-oxazines through ring expansion of isoxazoles by rhodium carbenoids

Studies related to the total synthesis of elisabethin C led to the discovery of a rhodium-catalyzed cascade sequence involving isoxazole ring expansion and a [4+3] cycloaddition. The scope of the isoxazole ring expansion was explored, resulting in the synthesis of a range of 2H-1,3-oxazines in 47-96% yield.     

One-pot synthesis of 3-(furan-2-yl)-4-hydroxy-2H-chromen-2-ones using K10 montmorillonite clay as heterogeneous catalyst

A facile and efficient one-pot synthesis of 3-(furan-2-yl)-4-hydroxy-2H-chromen-2-ones was developed. The reaction of ethyl 3-(2-hydroxyphenyl)-3-oxopropanoates and 2,5-dimethoxy-2,5-dihydrofuran were performed in presence of K10 Montmorillonite Clay heterogeneous catalyst under the solvent-free condition at 80?°C for 1?h, and followed by further converted to 3-(furan-2-yl)-4-hydroxy-2H-chromen-2-ones via refluxing in the alkaline EtOH solution for 0.5?h. The demonstrate method not only avoided the usage of any expensive transition-metals, but also eliminated the tedious intermediate purification. Moreover, due to the wide functional group tolerance, it could be applied to various substrates and gave product in good to excellent yields.     

Fe(NO3)3 as an efficient catalyst for regio- and stereo-controlled ring expansion of 1,2-diaroyl-3-arylaziridines

Several 1,2-diaroyl-3-arylaziridines were previously prepared conveniently and used in the preparation of 5-benzoyl-2,4-diaryl oxazolines in the presence of NaI. In this work, synthesis of some trans-4-benzoyl-2,5-diaryl oxazolines by a regio- and stereo-controlled reaction in the presence of Iron (III) nitrate at room temperature is reported. A plausible mechanism has been proposed for ring expansion of N-acyl aziridines to oxazolines.     

Ceria/vinylpyridine polymer nanocomposite: an ecofriendly catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones

The three-component condensation of aldehydes, β-ketoesters and urea has been carried out in water using ceria (cerium oxide, CeO₂) nanoparticles supported on poly(4vp-co-dvb) as a catalyst for the preparation of 3,4-dihydropyrimidin-2(1H)-ones in good yields. The catalyst was recovered easily and reused without loss of its activity.     

1,6-dihydro-3(2H)-pyridinones as synthetic intermediates. Total synthesis of (±)-tecomanine

The first and stereoselective total synthesis of (±)-tecomanine ($\text{1}$) has been achieved from ethyl 1,6-dihydro-3(2H)-pyridinone-1-carboxylate ($\text{2}$) as a synthon.     

New fluorinated 1,3-vinylogous amidines as versatile intermediates: synthesis of fluorinated pyrimidin-2(1H)-ones

The condensation of the azaenolates derived from readily available ketimines with fluorinated nitriles offers an efficient and straightforward entry to new fluorinated 1,3-vinylogous amidines. These versatile compounds, in turn, react with triphosgene to yield new fluorinated pyrimidin-2(1H)-ones in high yields.     

One-pot synthesis of quinolin-2-(1H)-ones via tandem Ugi-Knoevenagel condensations

A new application of the Ugi reaction in the synthesis of heterocyclic compounds is described. Substituted quinolin-2-(1H)-ones are formed in one-pot sequential Ugi four-component condensation and intramolecular Knoevenagel cyclization between o-acylanilines, aldehydes, malonic or tosylacetic acids and cyclohexyl isocyanide.     

One-pot synthesis of 2-imidazolines via the ring expansion of imidoyl chlorides with aziridines

We herein report a simple and convenient one-pot synthesis of highly substituted 2-imidazolines in a regiocontrolled and stereospecific matter through the ring expansion reaction of an imidoyl chloride with an aziridine, analogous to the Heine reaction.     

Calcium fluoride: an efficient and reusable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones and their corresponding 2(1H)thione: an improved high yielding protocol for the Biginelli reaction

A simple and effective synthesis of 3,4-dihydropyrimidinone derivatives from aldehydes, 1,3-dicarbonyl compounds, and urea/thiourea in ethanol by using calcium fluoride as catalyst has been described. Compared with classical Biginelli reaction conditions, this new method has the advantage of excellent yields and shorter reaction times. Also, the catalyst can be reused without any reduction in efficiency.     

One-pot synthesis of spiro-acridine/indoline and indoline derivatives using (MWCNTs)-COOH/La2O3 hybrid as an effective catalyst

Spiro-acridine/indoline and indoline derivatives were synthesized by the three-component reaction of isatin, dimedone, and amines or amino acids in the presence of acid-functionalized multiwalled carbon nanotubes/La₂O₃ (MWCNTs)-COOH/La₂O₃ hybrid (5 mol%) as a highly efficient catalyst in ethanol. The assigned structure was further established by CHN analysis, NMR, and FTIR spectra. (MWCNTs)-COOH/La₂O₃ was fabricated by the reaction of functionalized (MWCNTs)-COOH and La(NO₃)₃.6H₂O in acetic acid. Synthesis of La₂O₃ nanoparticles and their conjugation on the surface of MWCNT have been confirmed by FTIR, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy.     

Silica sulfuric acid: an efficient and reusable catalyst for the one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones

Silica sulfuric acid efficiently catalyzes the three-component Biginelli reaction between an aldehyde, a β-dicarbonyl compound and urea or thiourea in refluxing ethanol to afford the corresponding dihydropyrimidinones in high yields. The catalyst is reusable and can be applied several times without any decrease in the yield of the reactions.     

1,6-Dihydro-3 (2H)-pyridinones as synthetic intermediates. Formal synthesis of (±)-tabersonine and (±)-catharanthine

Formal synthesis of (±)-tabersonine (3) and (±)-catharanthine (4) has been achieved starting from ethyl 1,6-dihydro-3 (2H)-pyridinone-1-carboxylate (1a) as a common synthon.     

One-pot synthesis of 2-amino-4H-chromenes catalyzed by Fe(ClO4)3/SiO2

Russian Journal of General Chemistry - A highly efficient one-pot three-component synthesis of 2-amino-3-cyano-4H-chromenes has been developed by annulation of aldehydes, malononitrile and dimedone...     

Three-component synthesis of 3-(diarylmethyl)indoles using Fe(ClO4)3/SiO2 as catalyst

Russian Journal of Organic Chemistry - Three-component reaction of indole, aromatic aldehyde, and N,N-dimethyl aniline in the presence of silica-supported Fe(ClO4)3 as catalyst afforded the...     

1,6-dihydro-3(2H)-pyridinones as synthetic intermediates. A novel total synthesis of (±)-ibogamine and (±)-epiibogamine

A new synthesis of (±)-ibogamine ($\text{4}$) and (±)-epiibogamine ($\text{5}$), involving the intramolecular Michael addition of the keto unsaturated ester ($\text{11}$), is described.     

NaNO2/I2 as an alternative reagent for the synthesis of 1,2,3-benzotriazin-4(3H)-ones from 2-aminobenzamides

An efficient transformation of 2-aminobenzamides to 1,2,3-benzotriazin-4(3H)-ones in the presence of sodium nitrite (NaNO₂) and Iodine (I₂) is described. The reaction is proposed to proceed via formation of nitrosyl halide that induces nitrosylation of the amino group of 2-aminobenzamide leading to diazotization followed by intramolecular cyclization.     

Synthesis of N-aminopyrazoles by Fe(II)-catalyzed rearrangement of 4-hydrazonomethyl-substituted isoxazoles

A novel effective method is reported for the preparation of 1-amino-1H-pyrazole-4-carboxylic acid derivatives by Fe(II)-catalyzed rearrangement of isoxazoles having (2,4-dinitrophenylhydrazono)methyl substituent at C4. The reaction proceeds smoothly for both E and Z isomers of 4-(hydrazonomethyl)isoxazoles, and this means it is not necessary to separate mixtures of E/Z-isomers of the hydrazones prepared by reaction of 5-methoxy/pirrolidino-4-carbonylisoxazoles and 2,4-dinitrophenylhydrazine. The rearrangement proceeds via the formation of an aziridine intermediate which can be isolated in certain cases. The 2-nitro group in the synthesized 1-[(2,4-dinitrophenyl)amino]-1H-pyrazole-4-carboxylic esters can be selectively reduced in two steps via acylation of the amino group followed by hydrogenation-deacylation using H₂-Pd/C.     

One-pot synthesis of N-acyl-substituted sulfamides from chlorosulfonyl isocyanate via the Burgess-type intermediates

The title N-alkoxycarbonyl- or N-aryloxycarbonyl-substituted sulfamides were synthesised in one-pot in efficient yields from chlorosulfonyl isocyanate (CSI), alcohols and aqueous (or dry) amines via the corresponding water-resistant intermediates, carboxysulfamoylammonium salts (Burgess-type reagents), which were generated in situ by the deactivation of the corresponding water-sensitive N-(chlorosulfonyl)carbamates with tertiary amines.