1,3-Indanedione:An versatile building block

Indanone-containing compounds are very important components of various natural products,chemical drugs,agrochemicals and functionalized material fields.1,3-Indanedione is a typical cyclic 1,3-dicarbonyl compound with three contiguous reactive electrophilic and nucleophilic sites.The easily prepared 2-arylidene-1,3-indanediones are activeα,β-unsaturated carbonyl compounds and could act as 1,3-dipolarophile,1,4-dienophile and 1-oxa-1,3-diene,etc.On the other hand,the homodimer(bindone)and cyclotrimer(truxenone)derived from basecatalyzed self-condensation of 1,3-indanedione are also reactive carbonyl compounds.Therefore,1,3-indanedione and its derivatives can be employed as key substrates in various domino and multicomponent reactions.In this review,we summarized the recent progress on the domino and multicomponent reactions of 1,3-indanedione,especially on our achievements on the synthetic applications for the complex indanone-containing carbocyclic and heterocyclic compounds.

A microenvironment sensitive pillar[5]arene-based fluorescent probe for cell imaging and drug delivery

Dansylamide(DNSA) is a typical ICT probe that has a favorable serum albumin sensitivity. Inspired by this, we designed a microenvironment sensitive fluorescent probe 4 C-G through introducing DNSA into pillar[5]arene. Unlike DNSA, 4 C-G displayed differentiated sensitivity to multiple proteins, which was benefit from pillar[5]arene assisted the probe to form complexes with proteins. 4 C-G could not only be applied in imaging of Hep G2, but also act as a favorable drug carrier for regorafenib(REG) encapsulation.The 4 C-G-REG complex would aggregate into high drug-loading fluorescent nanoparticles in a physiological environment(pH 7.4). Such nanoparticles exhibited p H-triggered enrichment ability, which rapidly enriched REG in the acidic environment(pH 6.0). Furthermore, the complexation between 4 C-G and REG maintained the imaging property of the probe and the excellent anticancer activity of the drug on Hep G2.

Pillar[5]arene-based [3]rotaxanes: Convenient construction via multicomponent reaction and pH responsive self-assembly in water

Four pillar[5]arene based[3]rotaxanes(1-4)involving two 1,4-diethoxypillar[5]arene(DEP5)rings and a dumbbell-shaped component were successfully synthesized.The dumbbell-shape molecules contain one longer bridge,two triazole sites and two multicomponent stoppers.After threading DEP5 rings with linear guests(G1-G4)which contain two benzaldehyde units,the base catalyzed three-component reaction of dimedone,malononitrile and benzaldehyde was performed to construct the stoppers and connected the pseudorotaxanes with stoppers to generate 1-4.The structures of[3]rotaxanes and their self-assembly behaviors were characterized by 1 H NMR,13C NMR,NOESY,HR-ESI-MS,DLS and TEM technologies.We hope that pillar[5]arene based[3]rotaxanes may have potential applications in drug delivery systems and molecular devices.

Three-Component Reaction for Construction of Spiro[indoline- 3,7＇-thiazolo[3,2-a]pyridines] and Spiro[benzo[4,5]- thiazolo[3,2-a]pyridine-3,3＇-indolines]

The three-component reaction of thiazole （benzothiazole）, dialkyl but-2-ynedioate, and isatinylidene malononi- triles in toluene at 110-120 ℃ in a sealed tube afforded a mixture of cis/trans-isomers of functionalized di- astereoisomeric spiro[indoline-3,7＇-thiazolo[3,2-a]pyridines] and spiro[benzo[4,5]thiazolo[3,2-a]pyridine-3,3＇-in- dolines] in good yields. Both cis-isomers and trans-isomers were successfully separated out and fully characterized with spectroscopy and single crystal determination. Under similar conditions, the three-component reaction con- taining 2-（1,3-dioxo-lH-inden-2（3H）-ylidene）malononitrile resulted in spiro[indene-2,7＇-thiazolo[3,2-a]pyridine] derivatives.

Synthesis of Functionalized 1-Benzamido-1,4-dihydropyridines via a One-Pot Two-Step Four-Component Reaction

The one-pot four-component reaction of benzohydrazide,acetylenedicarboxylate,aromatic aldehydes and malononitrile in ethanol with triethylamine as base catalyst afforded functionalized 1-benzamido-1,4-dihydropyridines in satisfactory yields.Under similar conditions,picolinohydrazide or nicotinohydrazide can also be successfully utilized in the reactions to give corresponding functionalized 1,4-dihydropyridines.1H NMR data indicated that an equilibrium of cis/trans-conformations exist in 1-benzamido-1,4-dihydropyridines.

Molecular Diversity of Three-Component Reaction of β-Enamino Imide, Malononitrile and Cyclic α-Diketones

The base promoted three-component reaction of β-enamino imide, malononitrile and various cyclic α-diketones in acetonitrile showed interesting molecular diversity. The reactions with acenaphthylene-1,2-dione and ninhydrin afforded functionalized spiro[indene-2,4＇-pyrrolo[3,4-b]pyridines] and spiro[acenaphthylene-1,4＇-pyrrolo[3,4-b]- pyridines] in good yields. The similar reaction of phenanthrene-9,10-dione resulted in the formation of the unexpected complex phenanthro[9＇, 10＇：4,5]furo[2,3-c]pyrrolo[3,4-b]pyrroles in satisfactory yields.

Convenient Synthesis of Spiro[benzo[d]pyrrolo[2,1-b]thiazole- 3,2＇-indenes] Derivatives via Three-Component Reaction

The three-component reaction of N-phenacylbenzothiazolium bromides, aromatic aldehydes and indane-l,3- dione in ethanol at room temperature in the presence of triethylamine as base afforded functionalized spiro[benzo- [d]pyrrolo[2,1-b]thiazole-3,2＇-indenes] in good yields and with high diastereoselectivity. The 1H NMR data and sin- gle crystal structure clearly indicated that the obtained spiro compounds predominately have one diastereoisomer.

Diastereoselective Synthesis of Arylidene Bis（3-arylamino- acrylates） via One-pot Domino Reactions

The functionalized arylidene bis（3-arylaminoacrylates） were efficiently prepared by FeCl3 catalyzed one-pot domino reactions of primary amines, methyl propiolate and aromatic aldehydes. When isatins were utilized under similar conditions, only 2-oxoindolinyl 3-arylaminoacrylates were obtained in moderate yields. ^1H NMR data and single crystal structures indicated that this reaction has high diastereoselectivity.

Construction and investigation of photo-switch property of azobenzene-bridged pillar[5]arene-based[3]rotaxanes

Series of azobenzene-bridged pillar[5]arene-based [3]rotaxanes with different alkyl chain length of guest molecules were constructed by threading-endcapping method with alkylenetriazole as axile and tetrahydrochromene as endcapping group.The encapsulation of pillar[5]arenes were proved by highresolution mass,^(1) H NMR and NOESY spectra.The photo-responsive property were examined by irradiation of the synthesized [3]rotaxanes with 365 nm and blue light LED,which caused trans to cis and cis to trans isomerization,respectively.Irradiation of corresponding model guest compounds without pillar[5]arene encapsulation resulted in near completely trans to cis and cis to trans isomerization,indicating the existence of pillar[5]arenes is the determining factor for the comprised photo isomerization efficiency.

Diastereoselective Synthesis of Functionalized Tetrahydropyrimidin-2-thiones via ZnCl2 Promoted One-pot Reactions

In the presence of zinc chloride,the in situ generatedβ-enamino ester from the reaction of morpholine,piperidine and pyrrolidine with methyl propiolate reacted,with aromatic aldehydes and thiourea in ethanol resulting in the functionalized tetrahydropyrimidin-2-thiones in satisfactory yields and with good diastereoselectivity.When aromatic aldehydes bearing electron-withdrawing group were used in the reaction,the 4-hydroxytetrahydropyrimidin-2-thione derivatives were obtained as the main product.

Synthesis of Highly Stable Porous Metal-lminodiacetic Acid Gels from a Novel IDA Compound

In this work, a novel and simple flexible aromatic multi-carboxylate compound N,N＇（4,4＇-biphenylyl） iminodi- acetic acid （BP-IDA） was synthesized, with which two new stable metaMDA gels （denoted as MIGl and MlG2） with three-dimensional network structures have been prepared successfully by employing Cr^3＋ and Al^3＋ as the metal ions, respectively. The rheological performance was investigated by means of dynamic rheology measurement. The morphology and microstructure were characterized by scanning electron microscopy, transmission elec- tron microscopy, and X-ray diffraction technique. Nitrogen sorption isotherm measurement suggests that the MlG1 aerogel has considerable porosity with the Brunauer-Emmett-Teller specific surface area up to 760 m^2·g^-1. Owing to easy preparation, good stability, and three-dimensional network structure, the as-prepared metal-organic gels will possess potential applications in separation, catalysis, and drug delivery.

Selective Synthesis of 1,2-Diarylpyrrolo[3,4-b]pyridine-5,7- diones via Cyclization Reaction of β-Enamino Imides with Cinnamaldehydes

The novel 1,2-diaryl substituted pyrrolo[3,4-b]pyridine-5,7-diones were selectively synthesized in high yields by the base catalyzed cyclization reaction of 3-arylamino-l-methyl-lH-pyrrole-2,5-diones with cinnamaldehyde and its derivatives in acetonitrile at room temperature. However, when piperidinium trifluoroacetate was employed as catalyst, the reaction afforded a mixture of 1,2-diaryl and 1,4-diaryl substituted pyrrolo[3,4-b]pyridine-5,7-diones in comparable yields.