Synthesis of 1-aryl- benzocycloalkane derivatives via one-pot two-step reaction of benzocyclonone,tosylhydrazide, and arylboronic acid

A metal-free one-pot two-step reductive coupling reaction of benzocyclonone, tosylhydrazide, and arylboronic acid was developed for the formation of a C(sp³)–C(sp²) bond, which enabled the efficient synthesis of 1-aryl-benzocycloalkane compounds in moderate to good yields on a multi-gram scale. Moreover, five- and six-membered benzocyclic ketones are also suitable substrates for this reaction. Notably, this protocol was also found to be suitable for synthesizing 3-(3,4-dichlorophenyl)-2,3-dihydro-1H-inden-1-one, an important intermediate in the synthesis of indatraline.     

Synthesis of methylenedioxy-bearing 1-aryl-3-carboxylisoquinolines using a modified Ritter reaction procedure

This paper describes original approaches aimed at the preparation of electron-rich 1-aryl-3-carboxylisoquinolines. Our first attempt led to an efficient preparation of 1-hydroxyisoquinoline-3-carboxylic acid methyl ester starting from bromophthalide via a rearrangement of 2-acetylamino-2-(3-oxo-1,3-dihydroisobenzofuran-1-yl)-malonic acid dimethyl ester. However, as its eventual application to the synthesis of methylenedioxy-bearing substrates seemed rather long, a second approach involving an extension of the Ritter reaction to safrole was devised. We thus report that, under proper experimental settings, the use of 54% tetrafluoroboric acid in ether enables a Ritter reaction between safrole and 3,4,5-trimethoxybenzonitrile yielding 17% of 7-methyl-5-(3,4,5-trimethoxyphenyl)-7,8-dihydro-[1,3]dioxolo[4,5-g]isoquinoline. This acidic reagent avoids the extensive decomposition seen when using the classical Ritter reaction conditions (i.e.: concentrated sulfuric acid). Further chemical transformations of this methyl-bearing dihydroisoquinoline led to the methylenedioxy-bearing 1-aryl-3-carboxylisoquinoline. These derivatives are related to the peripheral benzodiazepine receptor ligand PK 11195 as well as falcipain-2 inhibitors and other potential antitumor agents.     

A one-pot three-component reaction to access 1-alkyl-2-aryl-5-nitrobenzimidazoles under solvent-free conditions

A novel and expeditious method to access 1-alkyl-2-aryl-5-nitrobenzimidazoles has been developed. Enlisting solvent-free conditions, 2-fluoro-5-nitroaniline, a primary amine, and substituted aldehyde were melted together in one-pot to generate a variety of 1-alkyl-2-aryl-5-nitrobenzimidazoles.     

An efficient one-pot synthesis of novel 4-aryl-1-methyloxindoles

An unprecedented synthetic approach to novel 4-aryl-1-methyloxindoles is described. The method involves the intramolecular palladium-catalyzed amidation of N-methyl-2,6-dibromophenylacetamide followed by an in situ Suzuki cross-coupling reaction with a (hetero)arylboronic acid in a one-pot reaction.     

Synthesis of biphenyl anilines using iodo phenylformamides via a one-pot Suzuki coupling reaction

We have developed a novel and economical synthesis of biphenyl anilines via a one-pot Suzuki coupling reaction with iodo phenylformamides. This literature is an unprecedented approach to biphenyl anilines replacing costly aminophenylboronic acids with economical iodo anilines for the preparation of biphenyl anilines. It also provides a viable synthesis toward substituted biphenyl anilines where the required aminophenylboronic acids are not readily available.     

Hydroamination/Heck reaction sequence for a highly regioselective one-pot synthesis of indoles using 2-chloroaniline

A one-pot indole synthesis consisting of a highly regioselective TiCl(4)-catalyzed hydroamination and a 5-endo Heck cyclization starting from 2-chloroaniline is described, using an in-situ generated, sterically hindered imidazol-2-ylidene palladium complex.     

Novel reaction of 1-aryl-2-bromodiazene 1-oxides with olefins. Synthesis of 1-aryl-2-(2-bromoalkyl)diazene 1-oxides

The addition of 1-aryl-2-bromodiazene 1-oxides to olefins yields 1-aryl-2-(2-bromoalkyl)diazene 1-oxides (4). A radical mechanism of the reaction has been suggested. Compounds4 decompose to give bromohydrazones of formaldehyde and aldehydes. The structural factors that affect the rate of this process are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 917–923, May, 1995.The work was carried out in the Scientific Educational Center of the Institute of Organic Chemistry of the RAS with financial support of the Russian Foundation for Basic Research (Project No. 93-03-18461).     

Synthesis of benzo[c]fluorenone through a one-pot cascade reaction using inden-1-one derivatives

A novel one-pot thermal cycloaddition of two indenones followed by a decarbonylation and dehydrogenation cascade afforded benzo[c]fluorenones regioselectively. Various substituted indenone derivatives were converted into their corresponding benzo[c]fluorenones in good to excellent yields.     

Synthesis of 1-aryl-2-propanones

A new convenient synthesis of a series of 1-aryl-2-propanones using aromatic amines as precursors, via diazo-reaction and improved Meerwein arylation reaction under mild conditions, was achieved. In addition, 1-[3,5-bis(trifluoromethyl)phenyl]-2-propanone is a new compound among the synthesized compounds. This approach is an efficient synthetic method for the aryl-propanones with different substituting groups. __________ Translated from Chinese Journal of Organic Chemistry, 2007, 27(10): 1244–1249 [译自: 有机化学]     

Synthesis of 1-aryl-5-chloropyrazoles

A method for obtaining 1-aryl-5-chloropyrazoles with vacant 3 and 4 positions by cyclization of 3,3-dichloro-2-propenal arylhydrazones is proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 42–45, January, 1990.     

Enantioselective synthesis of 1,5-anti- and 1,5-syn-diols using a highly diastereoselective one-pot double allylboration reaction sequence

Highly diastereo- and enantioselective syntheses of 1,5-disubstituted (E)-1,5-anti-pent-2-endiols 1 and (Z)-1,5-syn-pent-2-endiols 2 have been achieved via the one-pot coupling of two different aldehydes with either (E)-gamma-(1,3,2-dioxaborinanyl)-allyl]diisopinocampheylborane (4) or (E)-gamma-(4,4,5,5-tetraphenyl-1,3,2-dioxaborolanyl)allyl]diisopinocampheylborane (11), respectively. The indicated diols 1 and 2 are obtained in 63-95% yield with 89-96% ee and >/=20:1 diastereoselectivity in all cases. The bifunctional gamma-boryl-substituted allylborane reagents 4 and 11 were generated in situ by the hydroboration of allenes 3 and 10 with diisopinocampheylborane. The keys to the success of this method are the excellent stereocontrol in the allylboration step leading to 5 and the corresponding substituted methallylboronate derived from 11, the stereospecificity of the subsequent allylboration reaction of the substituted methallylboronate intermediates, and the ability of the diol auxiliary to induce equatorial or axial placement of the substituent alpha to boron in transition states 7 and 8.     

Synthesis of 1-aryl-2-alkenyldiazene 1-oxides

1-Aryl-2-alkenyldiazene 1-oxides were prepared by the reactions of 1-aryl-2-bromodiazene 1-oxides with olefins followed by dehydrobromination of the intermediate 1-aryl-2-(-bromoalkyl)diazene 1-oxides by triethylamine.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 924–927, May, 1995.This work was carried out at the Scientific Educational Center of the Institute of Organic Chemistry of the RAS with financial support of the Russian Foundation for Basic Research (Project No. 93-03-18461).     

Synthesis of highly functionalized piperidines by one-pot multicomponent reaction using tetrabutylammonium tribromide (TBATB)

Tetrabutylammonium tribromide (TBATB) has been found to be an efficient catalyst for the one-pot synthesis of highly substituted piperidines through a combination of 1,3-dicarbonyl compounds, aromatic aldehydes, and various amines in ethanol at room temperature. Atom economy, good yields, environmentally benign, and mild reaction conditions are some of the important features of this protocol.     

Synthesis of 2-aryl-4H-pyrano[2,3-b]pyridin-4-ones by a one-pot deprotection-cyclization reaction

An efficient synthesis of 2-aryl-4H-pyrano[2,3-b]pyridine-4-ones is reported, using a one-pot, two step process in the presence of pyridinium hydrochloride. The methodology is compatible with a series of functional groups useful for the synthesis of second generation analogs, as part of our SAR program. In addition, the method proved to be scalable (>100 g), allowing for efficient synthesis of material to support animal studies.     

An efficient synthesis of 3-aryl-2,3-dihydrothiophene-2-carboxamide derivatives by one-pot, four-component reaction

An efficient and convenient method for the preparation of 3-aryl-2,3-dihydr-othiophene-2-carboxamide derivatives in absolute ethyl alcohol by thiazolidine-2,4-dione, aromatic aldehyde, malononitrile and n-butylamine without using any other catalysts was reported. This methodology has the advantages of high yields, simple work-up procedure and mild reaction conditions.     

Synthesis of stilbene analogues by one-pot oxidation-Wittig and oxidation-Wittig-Heck reaction

Synthesis of symmetrical (and unsymmetrical) stilbene derivatives is achieved by a combination of one-pot steps of Kornblum type oxidation of benzyl halide, its simultaneous in situ formation of phosphonium salt, and subsequently their Wittig reaction. In other variant it is oxidized to aldehyde, treated with ylide generated from phosphonium salt (CH₃PPh₃X) to give styrene, and subjected to Pd catalyzed Heck reaction with arylhalide to give stilbenes as the three-step one-pot sequence.     

Synthesis of 2-phosphonopyrroles via a one-pot RCM/oxidation sequence

A four-step synthesis of 2-phosphonopyrroles is presented starting from suitable aldehydes. The key step in the synthesis involves a one-pot ring-closing metathesis/oxidation sequence of a functionalized alpha-aminoalkenyl phosphonate. Notwithstanding the presence of a nucleophilic nitrogen atom and high substitution patterns in the substrate, the results of the RCM reaction are excellent using mild reaction conditions. Furthermore, a synergism is observed between the RCM catalyst and the oxidizing agent, causing higher oxidation rates and allowing reaction for substrates that normally fail to ring close under standard RCM conditions.     

Synthesis of 4-aryl-2,3-dihydropyrroles via Rh-catalyzed intramolecular hydroamino-methylation reaction

The rhodium-catalyzed intramolecular hydroaminomethylation reaction, generating 4-aryl-2,3-dihydropyrroles, has been developed. Triphenylphosphine has been proved to be the excellent ligand to prepare the dihydropyrrole derivatives in up to 99% yield. This procedure provides an efficient and simple alternative route to synthesize 4-aryl-2,3-dihydropyrrole derivatives only in one step.