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We have developed a convenient synthetic protocol for efficient construction of significant dihydrobenzofuran and benzofuran scaffolds by Lewis base-mediated annulation reaction ortho -iminophenols and ortho -vinylphenols with MBH carbonates of isatins under mild and metal-free conditions. The selective generation of different kinds of dihydrobenzofuran and benzofuran derivatives was successfully achieved by employing different substituted isatin-derived MBH carbonates with ortho - N -tosyliminophenols and ortho -vinylphenols. The features included broad substrate scopes, excellent functional group compatibility, high molecular diversity, and atomic economy.

A convenient synthetic protocol for diverse fused chromenes was successfully developed by a three-component reaction of alkyl isocyanides, dialkyl but-2-ynedioates, and various cyclic 1,3-dipolarophiles containing o -hydroxyphenyl group. In the absence of any catalyst, the three-component reaction of alkyl isocyanides, dialkyl but-2-ynedioates, and 3-( o -hydroxyarylidene)indolin-2-ones in tetrahydrofuran at 60 °C resulted in unique functionalized spiro[cyclobuta[ c ]chromene-1,3'-indolines] in good yields and with high diastereoselectivity. However, the similar three-component reaction with 2-(5-halo-2-hydroxyarylidene)indolin-2-ones afforded unexpected chain products in satisfactory yields. In addition, the three-component reaction of alkyl isocyanides, dialkyl but-2-ynedioates, and 2-( o -hydroxyarylidene)-1,3-indanediones in tetrahydrofuran at 60 °C resulted in complex indeno[2',1':5,6]pyrano[3,4- c ]chromene derivatives in high yields and with high diastereoselectivity.

The domino reaction of alkyl and aryl isocyanides with two molecules of 2-arylidene-1,3-indanediones in acetonitrile at 80 °C resulted in unique functionalized spiro[dibenzo[ a , f ]azulene-6,2'-indenes] in good yields, in which the two 2-arylidene-1,3-indanediones acted as different building blocks to construct the polycyclic system. More importantly, the unprecedented anticipation of the ortho-position of benzylidene group to form a novel dibenzo[ a , f ]azulene ring through a formal [5 + 2] cycloaddition process was first observed. On the other hand, DABCO-promoted reaction of the isocyanides with two molecules of 2-arylidene-1,3-indanediones in acetonitrile at 80 °C afforded functionalized spiro[cyclopenta[ a ]-indene-2,2'-indene] derivatives.

p -TsOH-catalyzed cycloaddition of various 3-vinylindoles and (indol-2-yl)diphenylmethanols in acetonitrile gave the functionalized cyclopenta[ b ]indoles in good yields and with high diastereoselectivity via [3 + 2] cycloaddition reaction. More importantly, FeCl 3 -catalyzed annulation reaction afforded unexpected functionalized cyclohepta[1,2- b :4,5- b ']diindoles in satisfactory yields, in which a formal [4 + 3] cycloaddition and an unprecedented C3/C2 carbocation rearrangement were first confirmed by the determination of single-crystal structure.

A DABCO-promoted annulation reaction of bindone ([1,2'-biindenylidene]-1',3,3'-trione) and 3-methyleneoxindoles showed very interesting molecular diversity under different reaction conditions. The base-promoted annulation reaction of bindone and 3-phenacylideneoxindoles in DCM at room temperature afforded spiro[indeno[1,2- a ]fluorene-5,3'-indoline] derivatives in good yields and with high diastereoselectivity. However, the similar reaction of 2-(2-oxoindolin-3-ylidene) acetates resulted in Z / E -isomeric spiro[indeno[1,2- a ]fluorene-5,3'-indolines] with diastereomeric ratios of 2:1 to 10:1. On the other hand, the DABCO-promoted annulation reaction of bindone and 3-methyleneoxindoles in acetonitrile at different temperatures selectively gave spiro[benzo[5,6]pentaleno[1,6 a - b ]naphthalene-7,3'-indoline] derivatives and complex dispiro[indoline-3,6'-[4 b ,6 a ]ethanoindeno[1,2- a ]fluorene-14',3″-indolines] in satisfactory yields.

p -TsOH catalyzed Diels-Alder reaction of 2-(1-alkylindol-3-yl)naphthalene-1,4-diones and 3-phenacylideneoxindoles showed fascinating diastereoselectivity. The reaction with the hydrated p -TsOH afforded trans -isomers of dihydrospiro[indoline-3,6'-naphtho[2,3- c ]carbazoles] as major products. Alternatively, the reaction with anhydrous p -TsOH under a Dean and Stark apparatus predominately gave cis -isomer of dihydrospiro[indoline-3,6'-naphtho[2,3- c ]carbazoles]. On the other hand, the similar p -TsOH catalyzed reaction of 2-(indol-3-yl)naphthalene-1,4-diones with 3-arylideneindolin-2-ones afforded cis / trans -isomers of dihydrospiro[indoline-3,6'-naphtho[2,3- c ]carbazoles]. Additionally, the p -TsOH catalyzed reaction of 2-(indol-3-yl)naphthalene-1,4-diones with 2-arylidene-1,3-indanediones gave the expected spiro[indene-2,6'-naphtho[2,3- c ]carbazoles] in satisfactory yields.

In the presence of copper sulfate, the three-component reaction of aromatic aldehydes, ethylindole-3-acetate and 4-arylidene-5-methyl-2-phenylpyrazol-3-ones, in refluxing toluene afforded spiro[carbazole-3,4'-pyrazoles] in good yields with high diastereoselectivity. More importantly, the similar CuSO 4 promoted the four-component reaction of two molecular aromatic aldehydes with ethylindole-3-acetate and 5-methyl-2-phenyl-pyrazol-3-one resulted in 2,4-diarylspiro[carbazole-3,4'-pyrazoles] in satisfactory yields. Additionally, CuSO 4 promoted the four-component reaction of two molecular aromatic aldehydes, ethylindole-3-acetate and 2-phenylthiazol-4-one, in refluxing toluene gave 2,4-diarylspiro[carbazole-3,4'-thiazoles] with diastereomeric ratios in the range of 3:1 to 20:1.

A simple InBr 3 -catalyzed domino reaction of indoles, phenylacetylenes, and various 3-methyleneoxindolines in toluene is described. This reaction not only provided a convenient synthetic protocol for polysubstituted tetrahydrospiro[carbazole-1,3'-indolines] in good yields but also gave completely different diastereoisomers of the tetrahydrospiro[carbazole-1,3'-indolines] to that of the previously reported TfOH-catalyzed one-pot reaction of indoles, acetophenones, and 3-methyleneoxindolines. Additionally, the InBr 3 -catalyzed reaction of the initially prepared 1,1'-bis(indolyl)phenylethanes with 3-phenacylideneoxindolines also gave the corresponding tetrahydrospiro[carbazole-1,3'-indolines] in good yields and with excellent diastereoselectivity. The reaction mechanism involved the sequential in situ generation of reactive dienophilic 3-alkenylindole, the Diels-Alder reaction, and the Lewis acid controlled diastereoisomerization process.

Triethylamine promoted the pseudo-five-component reaction of aromatic aldehyde with four molecules of 1,3-indanediones in refluxing ethanol to give unique polycyclic bicyclo[2.2.2]octane derivatives containing bridged- and spiro-indanone scaffolds in good yields. The mechanistic studies supported that the reaction included base-catalyzed cyclotrimerization of 1,3-indanedione to give an active cyclic diene and the sequential Diels-Alder reaction with in situ generated 2-arylidene-1,3-indanediones as electron-deficient dienophiles. On the other hand, the pseudo-four-component reaction of salicylaldehyde with 1,3-indanedione afforded the dibenzo[ b , g ]indeno[1',2':3,4]fluoreno[1,2- d ]oxonines in high yields. This reaction clearly demonstrated the high efficiency, molecular convergence, atom-economy, and impressive selectivity of multicomponent reactions.

The catalyst-free domino reaction of α,β-unsaturated N -alkyl or N -arylaldimines with two molecules of 2-arylidene-1,3-indanediones in dry acetonitrile resulted in polysubstituted spiro[indene-2,3'-indeno[2',1':5,6]pyrano[2,3- b ]pyridines] in moderate to good yields and with high diastereoselectivity. The reaction mechanism included sequential aza/oxa-Diels-Alder reactions via both endo-transition states. On the other hand, the catalyst-free domino reaction of α,β-unsaturated N -arylaldimines with 2,2'-(arylmethylene)bis(1,3-indenediones) afforded the mixed diastereoisomeric dispiro[indene-2,1'-cyclohexane-3',2″-indene] derivatives in satisfactory yields. The reaction mechanism of this formal [3 + 3] cycloaddition was believed to proceed with sequential nucleophilic 1,4-/1,2-additions., Competing Interests: The authors declare no competing financial interest.

A highly efficient Cu-catalyzed 1,2-difunctionalization of various N-heteroarenes was developed with ether and alkyl halide at ambient temperature. This transformation involves the combination of oxidative coupling by Cu/TBHP and reduction process by 1,8-diazabicyclo[5.4.0]undec-7-ene. This method provides an efficient method to prepare various substituted dihydroazaarene derivatives via a free-radical process.

A HOTf catalyzed three-component reaction of indoles, acetophenones, and ( E)-3-phenacylideneoxindolinones resulted in the unexpected polysubstituted 3-(9 H-carbazol-2-yl)indolin-2-ones in good yields. A similar reaction with various cyclic ketones afforded the corresponding carbocyclic fused 3-(9 H-carbazol-2-yl)indolin-2-ones. On the other hand, ( E)-3-arylideneoxindolinones in the three-component reaction gave the expected spiro[tetrahydrocarbazole-3,3'-oxindoles] through a domino alkenylation/Diels-Alder reaction. The unusual different reactivity of ( E)-3-phenacylideneoxindolinones and ( E)-3-arylideneoxindolinones in the three-component reactions was believed to involve the different reaction paths caused by the existence of the carbonyl group.

An efficient and diastereoselective synthetic protocol for the construction of spiro[cyclohexane-1,3'-indolin]-3-en-2'-ones and spiro[cyclohexane-1,2'-inden]-3-ene-1',3'-diones was provided by HOAc-mediated domino reaction of pinacoles with typical dienophiles, such as 3-methyleneoxindolines and 2-arylideneindane-1,3-diones, in ionic liquid [Bmim]Br. This domino reaction involved the in situ generation of 1,3-dienes from acid-mediated dehydration of various pinacoles and the sequential Diels-Alder reaction., Competing Interests: The authors declare no competing financial interest.

A highly efficient Cu-catalyzed 1,4-difunctionalization of isoquinolinium salts was developed with ether and X - (X = Br, Cl) as the halogen source under mild conditions. This transformation involves the combination of oxidative coupling and copper-catalyzed halogen atom-transfer radical processes. This method not only provides an efficient way to prepare various substituted azaarenes but also achieves the selective construction of C(sp 2 )-X (X = Br, Cl) bonds from a halogen anion and nucleophilic carbon atom via a free-radical process.

TfOH-catalyzed one-pot sequential reaction of indoles, acetophenones (cyclic ketones), and various 3-methyleneoxindolines in toluene afforded polysubstituted tetrahydrospiro[carbazole-1,3'-indoline]s in satisfactory yields. 1 H NMR spectra and single-crystal structures indicated that the obtained tetrahydrospiro[carbazole-1,3'-indoline]s existing in an unusual trans-configuration. The reaction mechanism was believed to proceed with domino acid-catalyzed 3-alkenylation of indoles with acetophenones, Diels-Alder reaction of 3-alkyenylindoles with 3-methyleneoxindolines, and an acid-catalyzed diastereoisomerization process.

The base-promoted cycloaddition reaction of N -cyanomethylisoquinolinium chloride with 2-arylidene-1,3-indanediones in dry tetrahydrofuran resulted in the expected spiro[indene-2,1'-pyrrolo[2,1- a ]isoquinoline] derivatives. However, the triethylamine-promoted three-component reaction of N -cyanomethylisoquinolinium chloride, aromatic aldehydes, and two molecules of 1,3-indanediones in acetonitrile afforded unique spiro[benzo[ f ]imidazo[5,1,2- cd ]indolizine-4,2'-indene] derivatives in satisfactory yields through tandem double [3 + 2] cycloaddition reactions., Competing Interests: The authors declare no competing financial interest.

The reactions of vinyl malononitriles with 3-phenacylideneoxindoles in ethanol in the presence of DBU as base resulted in the functionalized spirocyclic oxindoles through the domino Michael addition and intramolecular nucleophilic addition to cyano group. On the other hand, the similar reaction in the presence of piperidine as base afforded the simple Michael addition products in good yields. The stereochemistry of the spirooxindoles was established with (1)H NMR data and single crystal structures.

Three-component reactions of triphenylphosphine, but-2-ynedioate, and isatylidene malononitrile (ethyl cyanoacetate) in dimethoxyethane resulted in triphenylphosphanylidene spiro[cyclopentane-1,3'-indolines] in satisfactory yields. Furthermore, similar three-component reactions of triphenylphosphine, hex-2-en-4-ynedioate, and isatylidene malononitrile (ethyl cyanoacetate) afforded functionalized spiro[cyclopent[3]ene-1,3'-indolines] in good yields. [Corrected]

The functionalized spiro[indoline-3,2'-pyridine]-3',4',5',6'-tetracarboxylates were efficiently synthesized by BF3·OEt2-catalyzed reactions of isatin-3-imines with acetylenedicarboxylates in methylene dichloride. Under similar conditions, the BF3·OEt2-catalyzed three-component reactions of acetylenedicarboxylates, arylamines, and isatins afforded functionalized spiro[indoline-3,4'-pyridine]-2',3',5',6'-tetracarboxylates in moderate yields.

A simple protocol for the construction of novel dispirocyclopentanebisoxindoles is accomplished by the base promoted domino reactions between two molecules of 3-phenacylideneoxindoles with the participation of solvents, alcohol, or other added nucleophiles such as amines or thiophenols. Significantly, this domino reaction results in the complex dispiro compounds with high yields and diastereoselectivity, which would allow construction of dispirocyclopentanebisoxindole with four and five diastereoisomeric centers using simple materials.

A facile synthetic protocol was developed for the efficient synthesis of complex dispirooxindole-fused heterocycles via a three-component reaction. The key strategies involve a domino 1,4-dipolar addition and Diels-Alder reaction of the in situ generated Huisgen 1,4-dipoles from the addition reaction of 4-dimethylaminopyridine with acetylenedicarboxylate to 3-phenacylideneoxindole.

Microporous polycarbazole via straightforward carbazole-based oxidative coupling polymerization is reported. The synthesis route exhibits cost-effective advantages, which are essential for scale-up preparation. The Brunauer-Emmett-Teller specific surface area for obtained polymer is up to 2220 m(2) g(-1). Gas (H(2) and CO(2)) adsorption isotherms show that its hydrogen storage can reach to 2.80 wt % (1.0 bar and 77 K) and the uptake capacity for carbon dioxide is up to 21.2 wt % (1.0 bar and 273 K), which show a promising potential for clean energy application and environmental field. Furthermore, the high selectivity toward CO(2) over N(2) and CH(4) makes the obtained polymer possess potential application in gas separation., (© 2012 American Chemical Society)

Cyclotriveratrylene (CTV) has attracted much attention because of its good chemical stability, small cavity, stable conformation, and facile modification. In this article, two water-soluble CTV derivatives (CTV-G and CTV-L) functionalized by glucose and lactose residues were synthesized, respectively. Unexpectedly, sugar-bearing CTVs exhibit a distinct photoluminescence, which might be ascribed to the enhanced planar conformation of cyclotriveratrylene ring derived from the spatial effect of bulky branch groups. The interaction between the water-soluble CTV derivatives and C(60) was investigated in organic solvent and aqueous solution, which was further characterized by fluorescence spectra, ultraviolet-visible spectra, and Raman spectra. CTV-G can associate with C(60) to form supramolecular complex with 1:1 molar ratio (K(a) = 1.38 × 10(5) M(-1), 298 K). As for CTV-L, a similar complex with a lower association constant (K(a) = 5.09 × 10(4) M(-1), 298 K) can also be formed.

A protocol has been developed for the efficient synthesis of structurally diverse 3,4-dihydropyridin-2(1H)-ones and 3,4-dihydro-2H-pyrans via four-component reactions of arylamines, acetylenedicarboxylate, aromatic aldehydes and cyclic 1,3-diketones. The selective formation of the very different pyridinone or pyran derivatives depends on the structure of cyclic 1,3-diketone. The key steps are proposed to involve Michael addition of the enamino ester formed in situ from the reaction of arylamine with dimethyl acetylenedicarboxylate to arylidine cyclic 1,3-diketones.

An efficient and practical synthetic method for the functionalized 2-amino hydropyridines and 2-pyridinones was successfully developed via the domino reactions of arylamines, methyl propiolate, aromatic aldehydes and the substituted acetonitriles with triethylamine as base catalyst. Reactions involving malononitrile and cyanoacetamide gave exclusively the 2-aminohydropyridines. On the other hand ethyl cyanoacetate resulted in the 2-pyridinones as main products.

A practical and efficient procedure for the preparation of the polysubstituted dihydropyridines was developed through a unique four-component reaction of aromatic aldehydes, malononitrile, arylamines, and acetylenedicarboxylate in ethanol in the presence of triethylamine as a base promoter. This four-component reaction is atom-efficient, high-yielding, and applicable to a wide variety of four-component reactions.