A Novel Reaction of 1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU) or 1,5‐Diazabicyclo[4.3.0]non‐5‐ene (DBN) with Benzyl Halides in the Presence of Water

1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU) reacted with benzyl halides in CH₂Cl₂/H₂O 1 : 1 (v/v) to afford a mixture of eleven‐membered cyclic amide 1 and seven‐membered cyclic amide 2 . When the reaction was carried out in EtOH/H₂O 1 : 1 (v/v), product 2 was obtained as the major product. 1,5‐Diazabicyclo[4.3.0]non‐5‐ene (DBN) gave the five‐membered cyclic amide 3 as the sole product under the same reaction conditions.     

1,8‐Diazabicyclo[5.4.0]undec‐7‐ene: A Remarkable Base in the Debromination of 4‐ or 5‐Substituted N‐Benzyl α‐Bromo‐α‐p‐Toluenesulfonylglutarimide

Debromination of N‐benzyl 4‐ or 5‐substituted α‐bromo‐α‐p‐toluenesulfonylglutarimides is achieved with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) to give the N‐benzyl 4‐ or 5‐substituted α‐p‐toluenesulfonylglutarimides. The DBU/THF system is applied to a new methodology for the synthesis of bicyclic glutarimide skeleton in moderate yields.     

One‐Pot synthesis of functional poly(methacrylate) by ATRP and 1,8‐Diazacyclo‐[5,4,0]undec‐7‐ene catalyzed transesterification

A facile one‐pot 1,8‐diazacyclo‐[5,4,0]undec‐7‐ene (DBU) catalyzed transesterification/atom transfer radical polymerization (ATRP) strategy has been successfully developed through the combination of copper/DBU‐catalyzed ATRP and DBU‐catalyzed transesterification reactions. Well‐defined poly(methacrylate)s with various side ester groups have been synthesized by ATRP and transesterification of acyl donor 2,2,2‐trifluoethyl methacrylate with various alcohols, such as benzyl alcohol, n‐butanol, iso‐propyl alcohol, methanol, triethylene glycol monomethyl ether, propargyl alcohol, and 6‐azido‐1‐hexanol by the one‐pot process. Kinetic studies indicate that the ATRP process proceeded in a controllable manner without the interference of the transesterification reactions. Expansion of the binary system to a higher level ternary system has been successfully achieved by the combination of copper(I)‐catalyzed azide–alkyne cycloaddition, transesterification, and ATRP reactions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2998–3003     

An Efficient One‐Pot Synthesis of Substituted 1H‐Naphtho[2,1‐b]pyrans and 4H‐1‐Benzopyrans (=Chromenes) under Solvent‐Free Microwave‐Irradiation Conditions

A facile heterogeneous synthesis of 3‐amino‐1‐aryl‐1H‐naphtho[2,1‐b]pyran and 2‐amino‐4‐aryl‐4H‐1‐benzopyran derivatives 3 and 5 , respectively, was carried out efficiently by one‐pot three‐component coupling of an aromatic aldehyde 1 , an active methylene compound 2 , and naphthalen‐2‐ol or a phenol 4 in the presence of 5‐Å molecular sieves under solvent‐free microwave‐irradiation conditions (Scheme 1 and 2, Tables 1 and 2). The catalyst was recovered and recycled (Table 3).     

One‐Pot ‘On‐solvent’ Multicomponent Protocol for the Synthesis of Medicinally Relevant 4H‐Pyrano[3,2‐c]quinoline Scaffold

‘One‐pot’ AcONa‐catalyzed transformation of salicylaldehydes, malononitrile and 4‐hydroxy‐1‐methylquinolin‐2(1H)‐one in the presence of a minimal quantity of EtOH results in fast (3 min) and efficient formation of unknown 2‐amino‐4‐(2‐hydroxyaryl)‐6‐methyl‐5‐oxo‐5,6‐dihydro‐4H‐pyrano[3,2‐c]quinoline‐3‐carbonitriles in 85–98% yields, which are potential pharmaceutical agents for treating disorders responsive to the induction of apoptosis, antiproliferation, or vascular disruption. This efficient ‘on‐solvent’ approach to the 4H‐pyrano[3,2‐c]quinoline scaffold represents a novel synthetic concept for multicomponent reaction (MCR) strategy and allows to combine the synthetic virtues of conventional MCR with ecological benefits and convenience of facile ‘on‐solvent’ procedure.     

A Simple and Efficient One‐Pot Synthesis of Multifunctional 5‐Aryl‐5H‐thiazolo[3,2‐a]pyrimidines

One‐pot economical and efficient synthesis of multifunctional 5H‐thiazolo[3,2‐a]pyrimidines by the reaction of 4‐aryl dihydrothiopyrimidines with propargyl bromide in the presence of inorganic base has been reported in very short time.     

A Simple One‐Pot Synthesis of Fully Substituted 1H‐Pyridone[1,2‐a]‐Fused‐1,3‐Diazaheterocycles

An efficient procedure for the synthesis of 7‐(aryl)‐8‐nitro‐2,3,6,7‐tetrahydroimidazo[1,2‐a]pyridinones, 8‐(aryl)‐9‐nitro‐3,4,7,8‐tetrahydropyridone[1,2‐a]pyrimidines and 9‐(aryl)‐10‐nitro‐2,3,4,5,8,9‐hexahydropyridone[1,2‐a]diazepine via one‐pot three component reaction of diamine, nitroketene dithioacetal (1,1‐bis(methylsulfanyl)‐2‐nitroethene), and coumarine‐3‐ carboxylic acid derivatives in EtOH under reflux conditions is reported. The advantages of this procedure are simplicity, easy purification, good yields, and catalyst‐free conditions. All products were confirmed by ¹H‐ and ¹³C‐NMR, IR, MS, and X‐ray crystal structure analyses.     

Synthesis of alcohol ester 12 in 1, 8‐diazabicyclo [5.4.0] undec‐7‐ene (DBU)‐based Self‐separation catalytic system

The synthesis of alcohol ester 12 is one of the valuable industrial processes, but it was impeded by poor separating property and recycling ability of the catalytic systems. Herein, four novel DBU‐based basic ionic liquids (DBILs) of [BDBU]IM, [BDBU]OH, [ODBU]IM, [[ODBU]OH were synthesized successfully by introducing the alkyl chains of 1‐bromobutane or 1‐bromooctane to 1,8‐diazabicyclo [5.4.0] undec‐7‐ene (DBU), and then, employing imidazole (IM^?) or hydroxide (OH^?) as counter ions. The above obtained four ionic liquids were applied in the synthesis of alcohol ester 12 in isobutyraldehyde (IBD)/aqueous media for the first time. Interestingly, after reaction, production of alcohol ester 12 can be self‐separated from ionic liquids/water (ILs/W) catalytic system automatically. Furthermore, the self‐separated ILs/W can be recycled and used in next catalytic reaction for at least 5 times without obvious loss of catalytic performance. In this work, the structure, purity, thermal stability and alkalinity of DBILs were characterized systematically. [BDBU]IM shows high alkalinity and thus enhances yield of 66.17%. From thermo gravimetric analyzer (TGA), [BDBU]IM also exhibits excellent thermal stability. So [BDBU]IM was chosen for the further studying. Furthermore, quantum chemistry is applied to calculate the interaction forces and electron energies of reactants by DFT, and the calculation results illustrate the feasibility of synthetic process of DBILs. The self‐separation strategy of DBILS in this work may open up a new avenue for the clean synthesis of other industrial products.     

A Convenient One‐Pot Three‐Component Approach for Regioselective Synthesis of Novel Substituted Pyrazolo[1,5‐a]pyrimidines Using Fe+3‐Montmorillonite as Efficient Catalyst

Novel pyrazolopyrimidines derivatives were synthesized regioselectivly in one‐pot three‐component approach by Fe⁺³‐montmorillonite catalyzed condensation of 3‐amino‐5‐methyl pyrazole, arylaldehydes, and dimethylmalonate in THF under ultrasonic irradiations and conventional conditions. This rapid method produced the products in short reaction times and good yields.     

Effective and Green One‐Pot Multicomponent Synthesis of Novel Derivatives of 4H‐Pyrans in the Presence of Hexamethylenetetramine as Catalyst in Water Medium

Hexamethylenetetramine catalyzes synthesis of new polyfunctionalized 4H‐pyrans by the reaction of aromatic aldehyde, malononitrile, and β‐keto esters via one‐pot three‐component procedure in water medium. Addition of reactants was performed by two methods led to achieve similar results. Using hexamethylenetetramine in catalytic amount not only represents the economic face of the reaction but also due to the use of water, a green and safe reaction condition is organized. Thus, the current strategy provides the benefits of high productivity, convenient operation, and environmental friendliness. The structure of all products were proved by elemental analysis, IR, ¹H NMR, and ¹³C NMR spectroscopy.     

An Efficient Synthesis of Tetracyclic Pyrano[2,3‐d]pyrimidines

A series of pyrano[2,3‐d ]pyrimidine derivatives have been synthesized by the reaction of 2‐amino‐3‐cyano‐4H‐pyrans and acetic anhydride with acid catalyst . This method is very efficient because of short reaction times and easy work‐up, and it provides an efficient and promising synthetic strategy for the construction of the tetracyclic pyrano[2,3‐d ]pyrimidine skeleton. The X‐ray crystal structures of products are confirmed, and the possible mechanism is provided in this paper.     

1,4‐Diazabicyclo[2.2.2]octane‐Catalyzed One‐Pot Synthesis of Pyrazolo[1,2‐a][1,2,4]triazole‐1,3‐diones under Ultrasound Acceleration

1,4‐Diazabicyclo[2.2.2]octane has been explored as an efficient catalyst to effect the three‐component condensation reactions between malononitrile, 4‐arylurazoles, and aromatic aldehydes in ethanol under ultrasound irradiation conditions. The reactions proceeded very rapidly under mild conditions to furnish the corresponding pyrazolo[1,2‐a][1,2,4]triazole‐1,3‐dione derivatives in excellent yields.     

Microwave‐Assisted One‐Pot Synthesis of Substituted 3‐Bromoimidazo[1,2‐a]pyridines and Imidazoheterocycles

Herein, an efficient, one‐pot microwave‐assisted synthesis of a diverse set of 3‐bromoimidazo[1,2‐a]pyridines is being reported with good yields (40–85%). The method involves electrophilic aromatic bromination using bromodimethylsulfonium ion generated in situ via oxidation of HBr salt by DMSO. This methodology was also applied to the synthesis of related imidazoheterocycles. Copyright © 2014 HeteroCorporation     

Polycyclic N‐Heterocyclic Compounds. Part 75: Synthesis of 2,4‐Disubstituted 5,6‐dihydro[1]benzoxepino[5,4‐d]pyrimidines and 12‐Substituted 1,2,4,5‐Tetrahydro[1]benzoxepino[4,5‐e]imidazo[1,2‐c]pyrimidines as Potential Antiplatelet Aggregators

Libraries of tricyclic 2‐substituted 4‐alkylamino‐5,6‐dihydro[1]benzoxepino[5,4‐d]pyrimidines and tetracyclic 12‐substituted 1,2,4,5‐tetrahydro[1]benzoxepino[4,5‐e]imidazo[1,2‐c]pyrimidines were synthesized as part of our research to develop new effective antiplatelet drugs. Several alkyl and aryl groups were used as substituents at the 2‐position. Evaluation of the effects of the newly synthesized compounds on collagen‐induced platelet aggregation revealed several promising antiplatelet candidates with potencies superior to aspirin.     

One‐Pot Three‐Component Synthesis of 6H‐chromeno[4,3‐b] or Cyclopenta[b]furo[3,2‐f]quinoline Derivatives

Two series of furo[3,2‐f ]quinoline‐2‐carboxylate were obtained via a three‐component reaction of aldehydes, 5‐aminobenzofuran‐2‐carboxylate, and 4‐hydroxy‐2H‐chromen‐2‐one or cyclopentane‐1,3‐dione in DMF under catalyst‐free condition in high yields. This one‐pot three‐component reaction provided an efficient method for the synthesis of fused polycyclic heterocycles for bioactive screening.     

Green One‐Pot Solvent‐Free Synthesis of Pyrazolo[1,5‐a]pyrimidines,Azolo[3,4‐d]pyridiazines,and Thieno[2,3‐b]pyridines Containing Triazole Moiety

Synthesis of pyrazolo[1,5‐a]pyrimidines, [1,2,4]triazolo[1,5‐a]pyrimidine, 8,10‐dimethyl‐2‐(5‐methyl‐1‐phenyl‐4,5‐dihydro‐1H‐1,2,3‐triazol‐4‐yl)pyrido[2′,3′:3,4]‐pyrazolo[1,5‐a]pyrimidine, benzo[4,5]imidazo[1,2‐a]pyrimidine via heterocyclic amines, and sodium 3‐hydroxy‐1‐(5‐methyl‐1‐phenyl‐1H‐1,2,3‐triazole‐4‐yl)prop‐2‐en‐1‐one were carried out. Also, synthesis of isoxazoles, and pyrazoles from sodium 3‐hydroxy‐1‐(5‐methyl‐1‐phenyl‐1H‐1,2,3‐triazole‐4‐yl)prop‐2‐en‐1‐one and hydroxymoyl chlorides and hydrazonoyl halides, respectively, were made. Analogously, (1,2,3‐triazol‐4‐yl)thieno[2,3‐b]pyridine derivatives were obtained from sodium 3‐hydroxy‐1‐(5‐methyl‐1‐phenyl‐1H‐1,2,3‐ triazole‐4‐yl)prop‐2‐en‐1‐one and cyanothioacetamide followed by its reacting with active methylene compounds. In addition to full characterization of all synthesized compounds, they were tested to evaluate their antimicrobial activities, and some compounds showed competitive activities to those of tetracycline, the typical antibacterial drug, and clotrimazole, the typical antifungal drug.     

Retracted: Effective and Green One‐Pot Multicomponent Synthesis of Novel Derivatives of 4H‐Pyrans in the Presence of Hexamethylenetetramine as Catalyst in Water Medium

Hexamethylenetetramine (HMTA) catalyzes synthesis of new polyfunctionalized 4H‐pyrans by reaction of aromatic aldehyde, malononitrile, and β‐keto esters via one‐pot three‐component procedure in water medium. Addition of reactants was performed by two methods led to achieve similar results. Using HMTA in catalytic amount not only represents the economic face of the reaction, but also due to the use of water, a green and safe reaction condition is organized. Thus, the current strategy provides the benefits of high productivity, convenient operation, and environmental friendliness. Structure of all products was proved by elemental analysis, IR, ¹H‐NMR, and ¹³C‐NMR spectroscopy.