InCl3-catalyzed efficient one-pot synthesis of 2-pyrrolo-3′-yloxindoles

An InCl₃-catalyzed one-pot synthesis of 2-pyrrolo-3′-yloxindoles was achieved via three-component reaction of 3-phenacylideneoxindole, β-keto ester, and ammonium acetate at reflux by a sequential Michael addition followed by Paal-Knorr condensation.     

An efficient and one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles catalyzed by InCl3·3H2O

InCl₃·3H₂O was found to be a mild and effective catalyst for the efficient, one-pot, three component synthesis of 2,4,5-trisubstituted imidazoles at room temperature. Moreover, the utility of this protocol was further explored conveniently for the one-pot, four component synthesis of 1,2,4,5-tetrasubstituted imidazoles in high yields.     

InCl3 catalyzed carbene insertion into O-H bonds: efficient synthesis of ethers

An efficient InCl₃ mediated insertion of the carbene fragment (:CHCO₂Et), generated in situ from ethyl diazoacetate into O-H bond of a series of saturated and unsaturated alcohols under mild conditions has been developed to afford the corresponding ethers as exclusive products in good to high yields (70-95%) and in shorter reaction times. In the case of unsaturated alcohols, the reaction proceeded with unprecedented selectivity resulting in ethers as the only products and in high yields.     

Silica gel supported InBr3 and InCl3: new catalysts for the facile and rapid oxidation of 2′-hydroxychalcones and flavanones to their corresponding flavones under solvent free conditions

Silica gel supported InBr₃ or InCl₃ (15-20 mol %) were explored as a new solid-support catalysts for the facile and efficient oxidation, under solvent free conditions, of 2′-hydroxychalcones and flavanones to yield the corresponding flavones in >80% yield. The catalysts are easily prepared, stable, and efficient under mild reaction conditions.     

A novel one-pot and efficient procedure for the synthesis of 3H-spiro[isobenzofuran-1,6′-pyrrolo[2,3-d]pyrimidine]-2′,3,4′,5′-tetraones

A novel and practical one-pot procedure is described for the preparation of several new of 3H-spiro[isobenzofuran-1,6′-pyrrolo[2,3-d]pyrimidine]-2′,3,4′,5′-tetraones based on the addition reaction of ninhydrin and 6-aminouracils followed by oxidative cleavage of their corresponding dihydroxyindenopyrrolopyrimidines.     

An efficient synthesis of new 1-H-4′-methyl-3′,4′-dihydrospiro[piperidine-4,2′(1′H)quinoline] scaffolds

Efficient synthesis of new 3′,4′-dihydrospiro[piperidine-4,2′(1′H)quinolines] by a four step synthetic route based on 1-benzyl-4-piperidone reactivity is reported.     

First synthesis of 4-aminopyrido[2′,3′:4,5]furo[3,2-d]pyrimidines

This Letter describes for the first time the synthesis of pyrido[2′,3′:4,5]furo[3,2-d]pyrimidines substituted by a primary or secondary amino group on position 4 of the pyrimidine ring. Application of microwave irradiation technology allowed fast and convenient procedures.     

InCl3-catalyzed efficient synthesis of spiro-perimidine derivatives

InCl₃ was found to be a mild and effective catalyst for the simple and efficient synthesis of spiro-perimidine derivatives by the reaction of naphthalene-1,8-diamine and active carbonyl compounds in water at room temperature. This protocol includes some important aspects like the use of water as a “green” reaction medium, good yielding of products and mild reaction conditions.     

Rare earth perfluorooctanoate [RE(PFO)3] catalyzed one-pot synthesis of benzopyran derivatives

Rare earth perfluorooctanoate [RE(PFO)₃] catalyzes facile condensation of dimedone, aldehydes and malononitrile under mild conditions to afford the corresponding 5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran derivatives in good to high yields. The catalyst can be easy to prepare, stable and storable, easily recycled and reused for several cycles with consistent activity.     

InCl3-catalyzed four-component reaction: a novel synthesis of N-carbazolyl dihydropyridines

We have developed a simple, efficient, and environmentally benign microwave-assisted InCl₃-catalyzed synthesis of N-carbazolyldihydropyridines via a four-component reaction of 3-amino-9-ethylcarbazole, malononitrile, aromatic aldehydes, and acetylenic esters. The use of microwave heating allowed for reduced reaction times and resulted in higher yields. This four-component reaction is atom-efficient, high-yielding, and applicable to a wide variety of four-component reactions.     

An efficient synthesis of 5-substituted 1H-tetrazoles via B(C6F5)3 catalyzed [3+2] cycloaddition of nitriles and sodium azide

A simple and efficient protocol is developed for the synthesis of 5-substituted 1H-tetrazole derivatives from various nitriles and sodium azide (NaN₃) via [3+2] cycloaddition reaction using B(C₆F₅)₃ as a catalyst. The present synthetic method displayed significant advantages such as low catalyst loading, mild reaction conditions, low toxicity, easy work-up, high yields, and compatibility with other functional groups.     

A facile synthesis of pyrrolo[1,2-a]benzimidazoles and pyrazolo[3,4:4′,3′]pyrrolo[1,2-a]benzimidazole derivatives

Reaction of 2-cyanomethylbenzimidazole 1 with hydrazonoyl halides 2 led to formation of pyrrolo[1,2-a]benzimidazole derivatives 7. Similar reaction of 1 with halides 3 afforded 5-amino-4-(benzimidazol-2-yl)pyrazole derivatives 11 or 1-amino-2-arylpyrazolo[3,4:4′,3′]pyrrolo[1,2-a]benzimidazol-4-one 14 depending on the reaction conditions. The mechanisms of the studied reactions are discussed.     

InCl3 and ZrCl4 catalyzed regioselective reaction of 2,2′-dihydroxybiphenyl with terminal alkynes: synthesis of new dibenzo[d,f][1,3]dioxepines

The regioselective reaction of 2,2′-dihydroxybiphenyl with terminal alkynes was found to be rapidly catalyzed by InCl₃ and ZrCl₄. The chemoselectivity of catalysts and alkynes for biphenol over water, together with the reaction mechanism are discussed in details.     

Chiral 2-C-methylene glycosides and carbohydrate-derived pyrano[2,3-b][1]benzopyrans: synthesis via InCl3 catalyzed stereoselective Ferrier rearrangement of 2-C-acetoxymethyl glycal derivatives

2-C-Acetoxymethyl glycal derivatives react with aliphatic alcohols in the presence of InCl₃ (30 mol %) to furnish the corresponding 2-C-methylene glycosides in excellent yields and with exclusive α-selectivity except for the methyl 2-C-methylene glycosides, which are formed in ∼2:1 anomeric ratio in favour of the α-anomer. The reaction of 2-C-acetoxyglycals with phenols, however, produces the corresponding chiral carbohydrate-derived pyranobenzopyran derivatives via initial Ferrier rearrangement followed by tandem cyclization in excellent yields and moderate to high stereoselectivities in favour of the corresponding 10a-R-pyrano[2,3-b][1]benzopyran derivatives.     

InCl3/Al mediated pinacol coupling reactions of aldehydes and ketones in aqueous media

A systematic work on the homo-pinacol coupling reactions of benzophenones, aldehydes, and acetophenones in aqueous media with InCl₃/Al is described for the first time, in which various 1,2-diols are obtained in moderate to good yields.     

Pyrazolo[2′,3′:3,4][1,3]oxazino[5,6-b]quinoxaline, a novel tetracyclic ring system

Reaction of 2-chloro-3-(3-chloro-1H-pyrazol-5-yl)quinoxaline and aldehydes does not afford the corresponding N-(α-hydroxyalkylated) derivatives but results in a cyclisation reaction to give a derivative bearing the hitherto undescribed pyrazolo[2′,3′:3,4][1,3]oxazino[5,6-b]quinoxaline system.     

A novel and efficient catalytic system including TEMPO/acetaldoxime/InCl3 for aerobic oxidation of primary amines to oximes

A simple and efficient catalytic system including TEMPO/acetaldoxime/InCl₃ for aerobic oxidation of primary amines to corresponding oximes by using toluene as the solvent is described. This practical method can use O₂ as the economic and green oxidant, tolerate a wide range of substrates, which can afford the target oximes in moderate to excellent yields.     

A facile one-pot synthesis of 2-substituted-3-aminoquinolines: preparation of benzo[b]naphthyridine-3-carbonitriles

A facile one-pot synthesis of 3-aminoquinolines from ortho-aminobenzaldehydes was developed. Ethyl 6,7-dimethoxy-3-aminoquinoline-2-carboxylate, a key intermediate for the preparation of a 4-anilino-benzo[b][1,5]-naphthyridine-3-carbonitrile, was efficiently prepared by this method. Synthetic routes to 4-anilino-benzo[b][1,5]-naphthyridine-3-carbonitrile and 4-anilino-benzo[b][1,8]-naphthyridine-3-carbonitrile are described     

Synthesis and tautomeric structure of 6-arylhydrazono 1H-pyrazolo[3′,4′:4,5]pyrimido[1,6-b][1,2,4]triazepines

A simple synthetic strategy is described for synthesis of the hitherto unreported 6-arylhydrazono-1,3-diphenyl-7-methyl-1H-pyrazolo[3′,4′:4,5]pyrimido[1,6-b][1,2,4]triazepin-5(6H)-ones 5a-j. The acid dissociation constants were determined for the series prepared and were correlated by the Hammett equation using the enhanced substituent constants. The results of such a correlation together with the spectral data indicated that the studied compounds exist predominantly in the hydrazone tautomeric form.     

A simple route for the synthesis of 3,3,3′,3′-tetramethyl-2,3,3′,4′-tetrahydro-1H,1′H-[4,9′-bixanthene]-1,1′(2′H,9′H)-dione and its derivatives catalyzed by Mn and other transition metal cations

A simple and efficient unusual coupling reaction of 9-(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-en-1-yl)-3,3-dimethyl-2,3,4,9-tetrahydro-1H-xanthen-1-one and its derivatives was accomplished in the presence of Mn²⁺, Cu²⁺, Cd²⁺, Hg²⁺, Fe³, or La³⁺. The structure elucidation was accomplished by IR, ¹H NMR, ¹³C NMR, X-ray crystallography, UV-Visible and elemental analysis. A reaction mechanism is proposed.