Preparation of cyclohepta and benzo[ef]cycl[3.2.2]azines

Some cyclohepta[ef]cycl[3.2.2]azines were prepared from cyclohepta[hi]indolizines and electron deficient acetylenes in the presence of appropriate oxidants. Also, benzo[ef]cycl[3.2.2]azines were obtained similarly in good yields.     

1,2-Dialkoxycarbonylhydrazine derivatives of pyrroles and indolizines. A new synthesis of cycl[3.2.2]azines

The reaction of pyrroles $\text{1}$ with diisopropyl azodicarboxylate $\text{2}$ yields 2- and 2,5-substituted derivatives. 3- and 1,3-substituted indolizines $\text{5}$ and $\text{6}$ are formed by the same route. Cycl[3.2.2]azines $\text{7}$ have been obtained from $\text{5}$ and $\text{6}$ with dimethyl acetylenedicarboxylate.     

Microwave promoted diastereoselective synthesis of dihydroindeno[1,2-b]furans via one-pot three-component reaction in solvent-free conditions

An efficient method was developed for the synthesis of fused dihydroindeno[1,2-b]furans. One-pot three-component reaction of 1,3-indanedione, aromatic aldehyde and pyridinium ylide in the presence of triethylamine under microwave-irradiation in solvent-free conditions afforded dihydroindeno[1,2-b]furans in a diastereoselective manner in excellent yields.     

Synthesis of cycl[3.2.2]azine and benzo[g]cycl[3.2.2]azine derivatives by use of the [2 + 8] cycloaddition reaction of indolizines and dimethyl acetylenedicarboxylate

The reaction of 1-ethoxycarbonylmethylpyridinium bromides 5a-k with nitro ketene dithioacetal, 1,1-bis-(methylthio)-2-nitroethylene ( 2 ), in the presence of triethylamine in ethanol gave the desired ethyl 2-methyl-thioindolizine-3-carboxylates 3a-k in good yields, along with ethyl 2-methylthio-1-nitroindolizine-3-carboxyl-ates 4a-d . Deesterification of 3 using sodium hydroxide in methanol followed by treatment with polyphosphoric acid gave the corresponding 2-methylthioindolizines 5a-d in good yields. The desulfurization of 5 with Raney-nickel in ethanol occurs smoothly to give the 1,2,3-unsubstituted indolizines 6a-c (a , parent indolizine; b , 8-methylindolzine; c , 6,8-dimethylindolizine). Similarly, pyrrolo[2,1-a]isoquinoline ( 19 ) was also synthesized. These indolizine and pyrrolo[1,2-a]isoquinoline derivatives were allowed to react with dimethyl acetylene to give the corresponding cycl[3.2.2]azine and benzo[g]cycl[3.2.2]azine derivatives in good results.     

Synthesis of 1-azacycl[3.2.2]azine and 1-azabenzo[h]cycl[3.2.2]azine

1-Azacycl[3.2.2]azines were synthesized from 2-methylthioimidazo[1,2-a]pyridines, 2a and 2b , by using [2 + 8] cycloaddition reaction with dimethyl acetylenedicarboxylate as the key step. Synthesis of 1-azabenzo-[h]cycl[3.2.2]azine was also described.     

Ultrasound promoted three-component synthesis of dihydroindeno[1,2-b]pyrrole derivatives

In this work, a one-pot three-component reaction of ninhydrin, primary amines, and 1,3-dicarbonyl compounds was investigated under various conditions to synthesis of diverse derivatives of dihydroindeno[1,2-b]pyrroles. Catalyst-free conditions in EtOH under ultrasound irradiation (45% of amplitude) were selected as a novel and efficient method for synthesis of these fused structures. The reactivity of different primary amines was then investigated for steric and electronic effects. Two examples of difunctional structures were also synthesized by using of 1,4-diaminobenzene under optimum conditions with high yields. The structure of all products was characterized by spectroscopic methods and elemental analysis.     

The synthesis of barbaralyl systems via bicyclic[3.2.2] irontricarbonyl cations

Reaction of bicyclo[3.2.2] tertiary alcohols 7b,c and 23b with Fe₂(CO)⁹, resulted in the corresponding dienyl Fe(CO)₃ complexes, which upon HBF₄/Ac₂O treatment yielded the bicyclo [3.2.2] dienyl irontricarbonyl cations. Nucleophilic addition of CN^- to those cations, resulted in the formation of δ,μ-bonded complexes, which were degraded with Me₃NO to give substituted tricydic hydrocarbons (barbaralyl systems) in unusual positions. For purpose of comparison, the trifluoroacetolysis of 2-methyl-endo-6,7-benzobicyclo[3.2.2] nonatriene (22) has been studied.     

Microwave promoted solvent-free one-pot three-component reaction to 2-pentafluorophenylquinoline derivatives

A novel and efficient one-pot multi-component reaction of pentafluorobenzaldehyde, alkynes and anilines for the synthesis of 2-pentafluorophenyl substituted quinolines under microwave irradiation and a solvent-free condition is presented.     

Asymmetric synthesis of multi-substituted spiro[5,5]undecane-1,5,9-triones via organocatalytic three-component reaction

The asymmetric domino three-component Knoevanagel-Diels-Alder addition (ATCDA) reaction, as an important methodology, has been utilized to construct complex product from ordinary starting materials. In this report, many typical organoamine catalysts were investigated to achieve highly efficient asymmetric three-component reaction of enones 2, aldehydes 3 and Meldrum’s acid 4. Various pharmacological multi-substituted spiro[5,5]undecane-1,5,9-triones promoted by 9-amino-9-deoxy-epi-quinine 1 g in one-pot, were obtained in moderate to good yields (up to 81%) with excellent diastereo-(>99:1 dr) and enantioselectivities (up to 97% ee). Meanwhile, based on the controlled experiments and analytical data, a reasonable mechanism of dual-activity for this reaction has been proposed.     

Light promoted aqueous phase amine synthesis via three-component coupling reactions

By applying a simple TiO₂–(NH₄)₂S₂O₈ system and promoted by UV light, the three-component reactions of cyclic ether, aniline and aldehyde can be progressed efficiently. 29 substituted amines with different structures were synthesized with up to 97% isolated yields. Isotope effect study revealed that the rate-determining step might be the nucleophilic addition step but not radical generation.     

Regio and diastereoselective synthesis of functionalized 2,3-dihydrofuro[3,2-c]coumarins via a one-pot three-component reaction

An efficient and straightforward synthesis of furo[3,2-c]coumarins via the one-pot three-component condensation of aromatic aldehydes, 4-hydroxycoumarin and α-chloroketones in refluxing n-propanol is described. Pyridine or a mixture of AcOH and AcONH₄ was used as a basic catalyst.     

An efficient synthesis of imidazo[2,1-b][1,3]thiazins via a one-pot,three-component and solvent-free reaction

A simple and eco-friendly method for the synthesis of novel imidazo[2,1-b][1,3]thiazin derivatives has been developed via the one-pot, three-component and solvent-free reaction of thiohydantoins, aromatic aldehyde and 5,5-dimethylcyclohexane-1,3-dione in the presence of catalytic amount of p-toluene sulfonic acid, in good and excellent yields.     

A novel microwave-mediated one-pot synthesis of indolizines via a three-component reaction

[reaction: see text] The microwave-mediated three-component reaction of acyl bromide, pyridine, and acetylene is catalyzed by basic alumina to give corresponding indolizines in excellent yields in a one-pot reaction.     

Synthesis of new 4-aroyl-pyrano[c]chromenes via a one-pot,three-component reaction based on aryl glyoxals

A new library of pyrano[c]chromenes containing an aroyl group has been synthesized by a novel multicomponent process involving the reaction of various aryl glyoxals with 4-hydroxycoumarin and malononitrile. The reactions were catalyzed efficiently by ammonium dihydrogen phosphate to yield the desired products in good to excellent yields.     

Convergent synthesis of dendrimers via the Passerini three-component reaction

Tuning properties by programming the surface functional group composition of surface-block dendrimers has been limited to dendrimers with only two types of surface functionality (i.e., surface-diblock dendrimers). The Passerini reaction provides dendrimer products from precursor dendrons in reasonable yields. This proof-of-principle experiment opens the door to making surface-triblock dendrimers.     

A new and efficient one-pot synthesis of 2-hydroxy-1,4-dihydrobenzoxazines via a three-component Petasis reaction

The secondary amines synthesized by the reaction between 2-aminophenols and aromatic aldehydes, via the reduction of the corresponding imines, were employed in the synthesis of new 2-hydroxy-2H-1,4-benzoxazine derivatives through a one-pot Petasis multicomponent reaction in good to excellent yields.     

Efficient one-pot synthesis of spiro[indoline-3,4′-pyrazolo[3,4-e][1,4]thiazepine]dione via three-component reaction

An efficient one-pot synthesis of spiro[indoline-3,4′-pyrazolo[3,4-e][1,4]thiazepine] dione derivatives via three-component reaction of 5-amino-3-methylpyrazole, isatin, and thioacid is described. This new protocol produces novel heptacyclic spirooxindole derivatives in good yields in comparison to conventional pentacyclic compounds. This method proceeds through a 3-(5-aminopyrazol-3-yl)-3-hydroxy-2-oxindoline intermediate (Baylis-Hillman type adduct), unlike 3-indolylimine (the intermediate like Shiff-Bases) as in conventional methods. The structure of one representative compound has been confirmed by X-ray diffraction analysis.     

An efficient diastereoselective synthesis of spiro pyrido[2,1-b][1,3]oxazines via a novel pyridine-based three-component reaction

The zwitterions generated from pyridine and dialkyl acetylenedicarboxylate (DAAD) reacted with benzofuran-2,3-diones to form highly substituted spiro pyrido[2,1-b][1,3]oxazines in good to high yields without using a catalyst.     

One-pot synthesis of 2-alkyl-7-amino-5-aryl-pyrazolo[1,5-a]pyrimidine-6-carbonitriles via a domino three-component condensation-oxidation reaction

A one-pot, domino three-component condensation reaction of an aldehyde, 3(5)-amino-5(3)-methylpyrazole and malononitrile in ethanol to give 2-alkyl-7-amino-5-aryl-pyrazolo[1,5-a]pyrimidine-6-carbonitrile in high yields at reflux condition without using any catalyst, is described.