Iron-catalyzed cascade reaction of ynone with o-aminoaryl compounds: a Michael addition-cyclization approach to 3-carbonyl quinolines

An efficient iron-catalyzed cascade Michael addition-cyclization of o-aminoaryl compounds including o-aminoaryl aldehydes, o-aminoaryl ketones, and o-aminobenzyl alcohols with ynones for the synthesis of 3-carbonyl quinolines is reported. The reactions proceed to afford 3-carbonyl quinoline derivatives with or without substituent at the C-4 position in good to high yields using Iron(III) chloride hexahydrate as the catalyst in the air.     

Silver-catalyzed cascade reaction of o-aminoaryl compounds with alkynes: an aniline mediated synthesis of 2-substituted quinolines

An efficient silver-catalyzed, aniline mediated cascade hydroamination/cycloaddition of o-aminoaryl compounds including o-aminoaryl aldehydes, o-aminoaryl ketones with alkynes for the synthesis of 2- or 2,4-substituted quinolines is reported. The reactions proceed with high regioselectivity to afford mono- or disubstituted quinoline derivatives in good to high yields using AgOTf as the catalyst in the air.     

Molecular iodine-catalyzed diastereoselective synthesis of cis-fused pyranobenzopyrans and furanobenzopyrans

A highly efficient method for the diastereoselective synthesis of cis-fused pyranobenzopyrans and furanobenzopyrans via 2 mol % of molecular iodine-catalyzed reaction of o-hydroxybenzaldimines with 3,4-dihydro-2H-pyran and 2,3-dihydrofuran at ambient temperature is described. 2-Butoxy-4-N-arylaminobenzopyrans were also synthesized from o-hydroxybenzaldimine and n-butyl vinyl ether using this procedure.     

Cyclization and oxidation of o-bromophenylacetamides for the synthesis of oxindoles and isoindigoes

N-substituted oxindoles were obtained through a facile KOH/DMSO promoted intramolecular cyclization of o-bromophenylacetamides in good yields. Furthermore, isoindigo derivatives were readily synthesized through sequential intramolecular cyclization, oxidation and condensation of o-bromophenylacetamide in the presence of copper (II) acetate monohydrate, iodobenzene diacetate and KOH/DMSO. This method provides a convenient synthesis of a range of oxindoles and symmetrical biologically important (E)-bisindole-2-ones using o-bromophenylacetamide as sole starting material. The reaction mechanism is elucidated in light of the control experiment results.     

Metal-free synthesis of benzimidazo[1,2-c]quinazolin-6-ones with indole and benzenediamine oxidized by I2/TBHP

A variety of benzimidazo[1,2-c]quinazolin-6-ones derivatives can be accessed in moderate to good yields under simple and metal-free reaction conditions using indoles and o-benzenediamines oxidized by iodine and TBHP. This procedure works in reasonable yields for different indoles as well as o-benzenediamines thus may provide a good synthesis of quinazolinones. A TBHP oxidized ring expansion reaction mechanism that explains the synthesis of benzimidazo[1,2-c]quinazolin-6-ones were reported.     

Comparative studies of chemically synthesized polyaniline and poly(o-toluidine) doped with p-toluene sulphonic acid

Polyaniline and poly(o-toluidine) doped with p-toluene sulphonic acid (p-TSA) were synthesized by in situ chemical polymerization method using ammonium per sulphate as an oxidizing agent. This is a novel polymerization process for the direct synthesis of emeraldine salt phase of the polymer. The polymers were characterized by using UV-Vis and FT-IR spectroscopy, SEM, elemental analyzer, TGA/DSC and conductivity measurements. Thermal analysis shows that poly(o-toluidine) is less thermally stable compared to polyaniline. The less conductivity in poly(o-toluidine) is due to the cumulative steric as well as electronic effect of the bulky methyl substituent present on the benzene ring. High temperature conductivity measurements show ‘thermal activated behavior’.     

Acyloxyalkylidènephosphoranes—III : Etude des ω-acyloxybenzylidènetriphénylphosphoranes.nouvelle voie d'accès aux benzofurannes

The intramolecular condensation of o-acyloxybenzylidenetriphenylphosphoranes leads to acylated products in t-BuOH and to benzofurans in toluene. Mechanistic aspects are discussed. A general method is described for the synthesis of benzofurans from o-cresols, o-hydroxybenzylic alcohols, and deactivated phenols.     

Une nouvelle voie d’acces aux indoles par condensation ylure-amide

Abstract-o-Acylaminobenzylidenephosphoranes lead to indoles in good yield by an intramolecular Wittig reaction with the amide carbonyl group. Mechanistic aspects are discussed. A general method is described for the synthesis of indoles from o-nitrobenzyl bromides and o-aminobenzyl alcohols.     

Facile synthesis of isoquinolines by imination and subsequent palladacycle-catalyzed iminoannulation of internal alkynes

An efficient and facile synthesis of isoquinolines has been described via a tandem reaction of imination of o-halobenzaldehydes with tert-butyl amine and subsequent palladacycle-catalyzed iminoannulation of internal alkynes. This tandem reaction could be carried out successively in one pot without any special operation, and the annulation step could afford isoquinolines derivatives in moderate to good yields with high regioselectivity. In addition, the simple synthesis of indoles was realized by palladacycle-catalyzed annulation of o-iodoaniline or o-bromoanilines with internal alkynes.     

A methodology for synthesis of primary o-phenylenebisphosphines and o-chlorophenylphosphines

On the basis of the reaction of ethynediylbisphosphonates and chloroethynylphosphonates with classical donor alka-1,3-dienes, a general strategy for synthesis of o-bisphosphanylbenzenes and o-chlorophosphanylbenzenes, which includes two consecutive steps: Diels-Alder condensation → aromatization of the carbocyclic phosphonate (bisphosphonate) formed → reduction of the phosphonate groups, was developed. Convenient procedures are devised for aromatization of phosphorus-containing cyclohexa-1,4-dienes and for reduction of o-phenylenebisphosphonates and o-clorophenylphosphonates to primary phosphines. A series of new alkylsubstituted phosphonic chlorides were prepared, and a possibility of functionalization of methylsubstituted o-phenylenebisphosphonates and o-clorophenylphosphonates by the methyl groups is demonstrated.     

New Heck coupling strategies for the synthesis of paullone and dimethyl paullone

The short total synthesis of paullone (1) and dimethyl paullone (2) via a novel palladium-catalyzed intramolecular coupling using the o-bromo- and o-iodo anilides of indoles (3 and 3a) and N-methyl indole 4 is described.     

The synthesis and characterisation of novel o-substituted benzyldi-t-butylphosphine-boranes

The novel compounds o-(chloromethyl)benzyldi-t-butylphosphine-borane and o-(methoxymethyl)benzyldi-t-butylphosphine-borane have been synthesised in 54% and 51% yields, respectively, and have been fully characterised. An improved method for the synthesis of α-chloro-α′-methoxy-o-xylene is also reported.     

Synthetic entry to 8-(o-nitrophenyl-2-azabicyclo[3.3.1]nonan-7-ones. Intermediates for the synthesis of strychnos-type systems.

The first synthetic route to 8-aryl-2-azabicyclo-[3.3.1]nonan-7-ones (e.g. 5) is reported. The synthesis involves acid cyclization of an appropriate 4-acetonyl-2-piperidinecarbonitrile (4) which, in turn, is obtained from the corresponding piperidine (3) by a modified Polonovski reaction. The o-nitrophenyl substituent of 3 is introduced by arylation of 4-piperidineacetoacetate 1 with o-fluoronitrobenzene followed by acid hydrolysis. The conversion of α-(o-nitrophenyl)ketone 5 to the bridged azocinoindole 7, an intermediate in the synthesis of deethyltubifolidine, is also reported.     

A new method for the cleavage of nitrobenzyl amides and ethers

A mild and efficient o- and p-nitrobenzyl cleavage protocol was developed. o- and p-nitrobenzyl groups were easily removed from a variety of substrates using 20% aqueous NaOH in methanol at 75 °C, presumably via oxidation at the benzylic position by oxygen dissolved in the solution. These easily introducible and removable nitrobenzyl groups can serve as valuable protecting groups for the synthesis of multifunctional, complex molecules.     

Highly selective synthesis of triptycene o-quinone derivatives and their optical and electrochemical properties

A convenient and efficient method for the selective synthesis of a series of triptycene o-quinone derivatives is described. The triptycene o-quinones, especially the ones containing the methoxy group(s) (electron donor) and the o-quinone group(s) (electron acceptor) simultaneously, show interesting intramolecular CT interactions and electrochemical properties. Moreover, DFT calculations display that introducing a strong electron-donor group into triptycene o-quinone results in an increasing of the HOMO energy level, which subsequently decreases the HOMO-LUMO energy gap.     

Iridium-catalyzed intramolecular CN and CO/S cross-coupling reactions: Preparation of benzoazole derivatives

The irdium-catalyzed intramolecular arylcarbon-hetero cross-coupling reactions with o-haloarylamides or o-haloarylamidine have been effectively achieved using KOAc and just 1 mol% catalyst. The [Ir(cod)Cl]₂ was proved to be more potential for smoothly assembling functional structures benzimidazoles, benzoxazoles and benzothiazoles, which was superior to Cu- and Pd-catalyzed systems. Simultaneously, a concise and efficient synthesis of tafamidis was developed in 5-g scale.     

Azidation vs [3 + 2]-cycloaddition: Chemoselective reaction of sodium azide towards o-alkynylaldehydes for the synthesis of N-heterocycles

The chemoselective synthesis of functionalized azido- and triazolo-containing nitrogen heterocycles using sodium azide and o-alkynylaldehydes has been described. The azidation reaction was preferred in acetonitrile while the [3 + 2]-cycloaddition was favored in DMSO. Furthermore, the azido-pyranoquinolines were employed for the synthesis of benzonaphthyridines via the Staudinger reaction at room temperature.     

Efficient method for the synthesis of diphosphine ligands with a heteroaryl-aryl bridge

A new efficient method for the synthesis of heteroaryl-aryl diphosphine ligands by direct double metallation of heteroaryl-aryls followed by phosphorylation of the resulting o,o′-dilithium salts is described. A number of new C₁-symmetric diphosphine ligands based on 3-arylheteroaryls, X-heteroaryls (X=N), and diphosphine ligands with a heterocyclic bridge with o-tolyl as the aryl fragment have been synthesized.     

The synthesis of some bidentate bismuth-containing ligands

The synthesis and properties including mass spectra of (o-diphenylphosphinophenyl)diphenylbismuthine, o-C₆H₄(PPh₂)(BiPh₂) and (o-diphenylarsinophenyl)-diphenylbismuthine, o-C₆H₄(AsPh₂)(BiPh₂) are described. The failure of attempts to prepare α, ω-bis(disphenylbismuthino)alkanes is discussed.