Thiourea dioxide (TUD): a robust organocatalyst for oxidation of sulfides to sulfoxides with TBHP under mild reaction conditions

Thiourea dioxide (TUD) has been reported for the first time as a highly efficient and selective organocatalyst for the oxidation of sulfides to sulfoxides in high to excellent yields by using tert-butylhydroperoxide as oxidant under mild reaction conditions.     

PEG-embedded thiourea dioxide (PEG.TUD) as a novel organocatalyst for the highly efficient synthesis of 3,4-dihydropyrimidinones

The host-guest complex between polyethylene glycol and thiourea dioxide (PEG.TUD) was prepared via different approaches involving co-crystallization method and by a chemical reaction. The resulting PEG.TUD complex was found to be very active and recyclable catalyst for the direct synthesis of 3,4-dihydropyrimidinones via Biginelli condensation and provided high product yields. Interestingly, the corresponding poly(ethylene glycol)-thiourea complexes, PEG.TU, were found to be unreactive and no reaction occurred under similar reaction conditions.     

吗啉催化的串联反应合成多取代环己酮（英文稿）

本文以吗啉为催化剂,活泼亚甲基化合物与芳香醛发生串联反应,以最高90%的产率得到了系列多取代的环己酮。反应经历了Knoevenagel缩合、Michael加成、Aldol反应等系列过程。吗啉作为有机分子催化剂,在串联过程中通过亚胺离子活化及烯胺活化羰基化合物而发挥重要作用。合成的环己酮可通过已知方法进一步转化为2-环己烯酮。本方法具有简便、易操作和绿色的特点。     

An efficient organocatalyzed multicomponent synthesis of diarylmethanes via Mannich type Friedel-Crafts reaction

We have developed an efficient organocatalyzed, multicomponent synthesis of diarylmethane derivatives from tertiary aromatic amines, formaldehyde and 2-naphthols via Mannich type Friedel-Crafts reaction. Several organocatalysts such as (−)-chinchonidine, l-proline, l-thiaproline, and l-pipecolonic acid have been screened for the reaction but the best results were obtained with l-proline. In this Mannich type Friedel-Crafts alkylation, tertiary aromatic amines react with formaldehyde-proline adduct to generate 1-(4-(dimethylamino)benzyl)pyrrolidinium-2-carboxylate intermediate, which undergoes nucleophilic addition to give substituted diarylmethanes in excellent yields.     

二氧化硫脲:一锅合成吡喃并[4,3-b] 吡喃类化合物的高效可重复使用有机催化剂（英文）简

A series of pyrano[4,3-b]pyran derivatives have been synthesized in excellent yields by the reaction of aromatic aldehydes with malononitrile or cyanoacetate and 4-hydroxy-6-methylpyran-2-one in water at 80℃, with the transformation being catalyzed by an aqueous solution of thiourea dioxide (TUD). Upon completion of the reaction, the product was isolated by filtration or extraction and the remaining aqueous TUD solution could be reused several times without any discernible impact on its catalytic activity. This procedure offers several advantages over existing procedures, including high yields, operational simplicity, the use of a non-toxic catalyst and solvent, short reaction time and minimum pollution of the environment, making it a useful and attractive process for the preparation of pyrano[4,3-b]pyran derivatives.     

Synthesis of polyhydroquinoline derivatives through unsymmetric Hantzsch reaction using organocatalysts

A novel and green approach for efficient and rapid synthesis of polyhydroquinoline derivatives via unsymmetric Hantzsch reaction using organocatalysts at room temperature was reported. The process is a simple, environmentally friendly, rapid, and high yielding reaction for the synthesis of polyhydroquinoline derivatives. The catalytic efficiency of various small organocatalysts such as l-proline, trans-4-hydroxy-l-proline, l-thiaproline, dl-phenylglycine, and (−)-cinchonidine was studied under aqueous, organic, and solvent free conditions.     

A green,isocyanide-based three-component reaction approach for the synthesis of multisubstituted ureas and thioureas

A one-pot, isocyanide based multicomponent protocol was presented starting from secondary amines towards (thio)urea derivatives and utilized for the construction of a diverse 27-membered chemical library. Following a green compatible microwave assisted condition, the formed N,N′-multisubstituted (thio)ureas were obtained in up to 85% yield.     

One-step, synthesis of Hantzsch esters and polyhydroquinoline derivatives using new organocatalyst

<正>Herein we report an efficient organocatalyst for the multicomponent Hantzsch reaction under mild condition.The product easily isolated by simple filtration and catalyst can be recovered.     

Titanium catalyzed one-pot multicomponent coupling reactions for direct access to substituted pyrimidines

A titanium-catalyzed 3-component coupling reaction can be used to generate tautomers of 1,3-diimines. These diimines produced in situ undergo condensation with amidines in a one-pot procedure to provide substituted pyrimidines. Seventeen examples of pyrimidines are provided using this one-pot, 4-component procedure from simple starting materials. In some cases, catalyst architecture can be tuned to control the regioselectivity of the alkyne addition. Finally, the regioselectivity of amidine addition to unsymmetrical 1,3-diimines is discussed.     

An efficient regioselective copper catalyzed multi-component synthesis of 1,3-disubstituted pyrazoles

An efficient synthesis of unsymmetrically substituted 1,3-pyrazole derivatives has been developed via three-component coupling reaction involving 3-(dimethylamino)-1-phenylprop-2-en-1-one, hydrazine, and aryl halides in one pot process exhibiting high regioselectivity. The pyrazole synthesis proceeds via a sequential series of reactions such as Michael addition, heterocyclization, dehydration, and Ullmann cross-coupling.     

One-pot synthesis of substituted indolines via a copper-catalyzed sequential multicomponent/C-N coupling reaction

One-pot synthesis of 2-(N-sulfonylimino)indolines has been developed. The procedure combines the copper-catalyzed three-component reaction of sulfonyl azides, o-bromophenylacetylenes, and amines and the copper-catalyzed intramolecular C-N coupling in one sequence, which afforded the products in moderate to good yields. The resulting 2-(N-sulfonylimino)indolines could be easily transformed to pharmaceutically valuable oxindoles (indolin-2-ones).     

Copper catalyzed magnesium-Barbier reaction for γ-selective alkyl-allyl coupling

CuCN catalyzed alkyl-allyl coupling under magnesium-Barbier conditions occurs regioselectively and affords predominantly the γ-products in good to high yields. This one-pot CuCN catalyzed reaction utilising Mg, an alkyl halide and an allylic substrate in THF at room temperature provides an easy alternative to the classical CuCN catalyzed γ-allylation of alkyl Grignard reagents.     

A concise Pd catalyzed cross coupling reaction along with deprotection for the synthesis of a new series of pyrimidine derivatives

A new series of 2-amino, 4-azepanone, 5-aryl substituted derivatives of pyrimidine compounds were synthesized for the first time from the commercially available 2-amino-4-hydroxypyrimidine. The key step in the reaction is a conceptually new single step palladium catalyzed cross coupling along with the deprotection of N,N-diisopropylformimidamide using bis(triphenylphosphine)palladium(II) dichloride (PdCl₂(PPh₃)₂).     

Acid-mediated synthesis of fully substituted 1,2,3-triazoles: multicomponent coupling reactions,mechanistic study,synthesis of serine hydrolase inhibitor and its derivatives

We describe the full details of multicomponent coupling reactions in acid-mediated synthesis of fully substituted 1,2,3-triazoles syntheses, and their applications to bioactive molecule synthesis. For substitution with wide range of nucleophiles, selection of acids or activating reagents was important, and various types of multicomponent coupling reactions were demonstrated, allowing functionalization with alcohols, amines, thiol, azide, and carbon nucleophiles. Four-component couplings including double triazolations were also tested. The efficiency of this method was demonstrated by the synthesis of serine hydrolase inhibitor and its novel substituted derivatives.     

A one-pot,multi-component reaction cascade for the rapid synthesis of diversely functionalized heteroaryl methyl substrates

A novel one-pot, “green” protocol to rapidly access pharmaceutically relevant heteroaryl methyl substrates is described. This process allows for a tandem S_N2/Suzuki-Miyaura reaction or Sonogashira reaction across a breadth of chemical diversity with yields ranging between 31 and 87% for the tandem Suzuki-Miyaura process and 50–66% for the tandem Sonogashira process. This procedure tolerates S, N, and O heteroatom linkers and is amenable for both rapid and robust lead development screening. In addition, T-type and N-type calcium channel blocker (15) was synthesized in 43% yield using this methodology which stands as an improvement in both yield and reaction time of the previously reported synthesis. The one-pot protocol also allows for the inclusion of greater chemical diversity within the scaffold of 15.     

Efficient synthesis of novel functionalized pyrazolo-pyranoquinoline and tetrahydrodibenzo-[1,8]naphthyridinone derivatives

The facile and efficient synthesis of 1,4-dihydropyrazolo-pyrano-[2,3-b]quinoline derivatives from the reaction of 2-chloroquinoline-3-carbaldehydes and pyrazolones is described. Moreover, a one-pot method for the development of functionalized tetrahydrodibenzo[b,g][1,8]naphthyridinone derivatives is reported by using a three-component reaction of 2-chloroquinoline 3-carbaldehydes, pyrazolone, and enaminones catalyzed by l-proline in EtOH.     

An efficient Morita-Baylis-Hillman reaction for the synthesis of multifunctional 2-hydroxy-3-nitrobut-3-enoate derivatives

An efficient thiourea promoted MBH reaction of various conjugated nitroalkenes with ethyl glyoxylate was developed. The desired multifunctional products, 2-hydroxy-3-nitro-4-aryl/alkylbut-3-enoate derivatives were obtained in good to high chemical yields (56-92%) with DMAP (20 mol %) under solvent-free conditions or imidazole (100 mol %) in the presence of water.     

Stereoselective synthesis of amides possessing a vinylsilicon functionality via a ruthenium catalyzed silylative coupling reaction

An effective stereoselective synthesis of E-N-2-(silyl)vinylamides via silylative coupling of vinyl amides such as N-vinylpyrrolidinone, N-vinylphthalimide, and N-vinylformamide with vinyltrisubstituted silanes catalyzed by [RuH(Cl)(CO)(PCy₃)₂] I is described.     

Biginelli reaction for synthesis of novel trifluoromethyl derivatives of bis(tetrahydropyrimidinone)benzenes

A facile one-pot three-component condensation of terephthalic aldehyde with urea and fluorinated 1,3-dicarbonyl derivatives is developed using catalytic quantities of chlorotrimethylsilane at ambient temperature. As a consequence, efficient synthesis of novel trifluoromethyl derivatives of bis(tetrahydropyrimidinone)benzenes is observed within short time periods. The procedure is shown to be equally efficient when urea is replaced with thiourea or guanidine.     

Cu catalyzed cross-dehydrogenative coupling reaction for the synthesis of 3-hydroxy-2-pyrrolidinones

A new convenient strategy for the synthesis of 3-hydroxy-2-pyrrolidinone derivatives featuring regioselective CC coupling has been developed. This is a Cu (II) catalyzed cross dehydrogenative coupling (CDC) involving enamino-ketones of benzyl amines and di-alkyl acetylenedicarboxylate, followed by cyclization by primary amines. TBHP (tert-butyl hydroperoxide) has been used as the oxidant to promote the coupling protocol. This synthetic route principally demonstrates the scope of CDC reaction and also applicable to gram-scale synthesis.