Reactions of <Emphasis Type="Italic">N</Emphasis>-acetyl- and <Emphasis Type="Italic">N</Emphasis>-ethoxycarbonyl-2-(1-cycloalken-1-yl)anilines with <Emphasis Type="Italic">meta</Emphasis>-cloroperbenzoic acid

Reaction of N-ethoxycarbonyl-2-(1-cycloalken-1-yl)anilines with meta-cloroperbenzoic acid leads to the corresponding 2-[1-o-(3-chlorobenzoyl)-2-hydroxycyclopent-1-yl]anilines. 5-(2-Acetylaminophenyl)-5-oxopentanic or 6-oxohexanic acids are formed as main products in the reaction of N-acetyl-2-(1-cycloalken-1-yl)anilines with m-chloroperbenzoic acid in CH₂Cl₂. N-Acetyl-2-(1-cyclopenten-1-yl)-3,6-dimethylaniline is an exception in this series since its reaction stops at the stage of epoxide formation.     

Unexpected conversion of alkyl azides to alkyl iodides and of aryl azides to N-tert-butyl anilines

In the presence of tert-butyl iodide, alkyl azides are converted into the corresponding iodides at room temperature, whereas, N-t-Bu anilines are obtained from aryl azides under the same experimental conditions. A mechanism is proposed to explain this unusual reactivity.     

Pd catalyzed coupling of 1,2-dibromoarenes and anilines: formation of N,N-diaryl-o-phenylenediamines

1,2-Dibromoarenes were coupled with aniline derivatives to yield N,N-diaryl-o-phenylenediamines in moderate to good yield using a palladium/phosphine or palladium/carbene catalyst system. Under similar conditions, 1,2,4,5-tetrabromobenzene was coupled with aniline derivatives to produce the corresponding tetrasubstituted derivatives which are oxidized on workup to yield azophenines. The sequential reaction of two different anilines with 1-chloro-2-iodobenzene afforded mixed N,N-diaryl-o-phenylenediamines.     

Regioselective ortho-nitration of N-phenyl carboxamides and primary anilines using bismuth nitrate/acetic anhydride

An efficient and one-pot synthetic method for the regioselective ortho-nitration of the N-phenyl carboxamides and primary anilines has been developed by using bismuth nitrate and acetic anhydride as the nitrating reagents. Reaction proceeds at room temperature and results in corresponding ortho-nitrated products in moderate to excellent yields. This method provides an operationally simple, regioselective, and efficient access to synthesize o-nitro anilines under the mild conditions.     

5-Aryl-2-furaldehydes in the Synthesis of 2-Substituted 1,3-Benzazoles

2-[2-(5-Aryl-2-furyl)ethenyl]-1,3-benzazoles were synthesized by reaction of 5-aryl-2-furaldehydes with 2-methylbenzoxazole, 2-methylbenzothiazole, 2-methylbenzimidazole, and 2-cyanomethylbenzimidazole. The corresponding benzazoles were also obtained by reaction of N-(5-arylfurfurylidene)anilines with 2-methylbenzoxazoles and of 3-(5-aryl-2-furyl)-2-cyanopropenoyl chlorides with o-phenylenediamine. The acylation of o-aminophenol with 3-(5-aryl-2-furyl)-2-cyanopropenoyl chlorides occurs at the amino group without subsequent oxazole ring closure.     

Heck-like coupling and Pictet-Spengler reaction for the synthesis of benzothieno[3,2-c]quinolines

A series of 6-arylbenzothieno[3,2-c]quinolines were synthesised in three steps from benzo[b]thiophene. After a selective Heck-type coupling of benzo[b]thiophene with different o-nitroaryl bromides to obtain 2-(o-nitroaryl)benzo[b]thiophenes, corresponding 2-(benzo[b]thiophen-2-yl)anilines were involved in a Pictet-Spengler reaction to form the quinoline cycle.     

Construction of nitrogen-heterocyclic compounds through zirconium mediated intramolecular alkene-carbonyl coupling reaction of N-(o-alkenylaryl)carbamate derivatives

Intramolecular alkene-carbonyl coupling reaction of N-benzyl-N-(o-alkenylaryl)carbamate derivative derived from o-aminostyrene, o-(aminomethyl)styrene and o-aminoallylbenzene smoothly proceeded by treating with zirconocene-butene complex to give the corresponding lactam derivative.     

Ligand‐free CuTC‐catalyzed N‐arylation of amides,anilines and 4‐aminoantipyrine: synthesis of N‐arylacrylamides, 4‐amido‐N‐phenylbenzamides and 4‐amino(N‐phenyl)antipyrenes

N‐Arylation of amides and anilines with aryl iodides was efficiently catalyzed by copper thiophenecarboxylate under ligand‐free conditions with good to excellent yields. A variety of substituted aryl iodides, amides, anilines and 4‐aminoantipyrine were found to be applicable to the simple catalytic system. Furthermore, some practical, unique secondary amides, such as N‐arylacrylamides and 4‐amido‐N‐phenylbenzamides, and 4‐amino(N‐phenyl)antipyrenes, which are difficult to obtain by the classical methods, were prepared. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis of o-(diphenylphosphinoyloxy)anilines by the rhodium-catalyzed reaction of nitroarenes and diphenylphosphine oxide

A rhodium complex Rh₂(OAc)₄ catalyzed the reaction of nitrobenzenes and diphenylphosphine oxide HP(O)Ph₂ giving o-(diphenylphosphinoyloxy)anilines predominantly, which were accompanied by small amounts of the p-isomers. Nitorobenzenes possessing a bulky o-substituent, particularly o-(t-butyl)nitrobenzenes, underwent the reaction in high yields. The reaction is considered to involve the reductive formation of O-phosphinoyl-N-arylhydroxyamines from nitrobenzenes, and o-phosphinoyloxylation by the rearrangement.     

A new convenient synthesis of phenanthrene alkaloids from 1-arylmethyl-1,2,3,4-tetrahydroisoquinolines

Hofmann degradation of 1-arylmethyl-1,2,3,4-tetrahydro-2,2-dimethylisoquinolinium iodides with methanolic KOH gave stilbene derivatives, for example, (E)-N-2{2-[2-(phenyl)ethenyl]-4,5-dimethoxyphenyl}ethyl-N,N-dimethylamine. Photochemical electrocyclization of these stilbenes afforded the corresponding phenanthrene alkaloids/phenanthrene derivatives.     

Reduction of ferrocenylmethyl quaternary ammonium iodides: Synthesis of methylferrocenes

A series of N-(2-substituted ferrocenylmethyl)-N,N,N-trimethylammonium iodides was reduced via sodium/ammonia and Emde reduction techniques to the corresponding 2-substituted methylferrocenes in order to examine the comparative utility of these two methods. Reduction of a series of N-(p-substituted benzyl)-N-ferrocenylmethyl-N,N-dimethylammonium halides demonstrated that both reductions apparently proceed through anionic intermediates.     

Sulfonamidation of halogen-substituted electrophiles with <Emphasis Type="Italic">N</Emphasis>-(2,2,2-trichloroethyl)arenesulfonamides

Reactions of N-(2,2,2-trichloroethyl)arenesulfonamides with primary alkyl bromides and iodides, allyl bromide, chloroacetonitrile, and benzyl chloride in acetonitrile on heating in the presence of potassium carbonate gave the corresponding N-alkyl-N-(2,2,2-trichloroethyl)arenesulfonamides.     

Reductive transformations of Schiff bases in the synthesis of functionally substituted heteroaromatic amines

Schiff bases synthesized by condensation of 5- and 6-aminoquinolines, 5-amino-2-methylquinoline, nitroanilines, and pyrimidinylaminoanilines with substituted benzaldehydes and pyridinecarbaldehydes were reduced with sodium tetrahydridoborate in acetic acid to obtain the corresponding N-aryl(hetaryl)benzylamines, N-(pyridylmethyl)anilines, and N-(1,2,3,4-tetrahydroquinolyl)benzylamine derivatives. The reduction of arylhetarylimines with hydrazine hydrate in the presence of Raney nickel involved only the azomethine C=N bond, while the nitrogen-containing heteroaromatic ring remained intact. Under analogous conditions, nitrosubstituted Schiff bases and benzyl- and pyridylmethylamines were converted into previously unknown N-(aminobenzyl)quinolinamines and aryl(pyridyl)methyl-substituted phenylenediamines.     

Palladium(II)-catalyzed Suzuki–Miyaura reactions of arylboronic acid with aryl halide in water in the presence of 4-(benzylthio)-N,N,N-trimethybenzenammonium chloride

This work reported that Suzuki–Miyaura coupling reactions of arylboronic acid with aryl bromide or iodides were mediated by Pd(OAc)₂ and 4-(benzylthio)-N,N,N-trimethylbenzenammonium chloride in the presence of Na₂CO₃ in water under the mild conditions. The corresponding Suzuki–Miyaura coupling products were obtained in good to excellent yields.     

Phosphine-free Pd-salen complexes as efficient and inexpensive catalysts for Heck and Suzuki reactions under aerobic conditions

Phosphine-free palladium-salen complexes, N,N′-bis(salicylidene)-ethylenediamino-palladium and N,N′-bis(salicylidene)-1,2-phenylenediamino palladium, are found to be highly active catalysts for the Heck olefination of aryl iodides and Suzuki reaction of aryl iodides and bromides giving excellent yields (70-90%) of products under aerobic conditions, in short reaction times (10-60 min).     

Nucleus- and side-chain fluorinated 3-substituted indoles by a suitable combination of organometallic and radical chemistry

Regioselectively fluoro-, trifluoromethyl- and trifluoromethoxy-substituted 3-methyleneindolines have been prepared using a four-step procedure involving metalation/bromination of fluorinated Boc-protected anilines, N-propargylation of the resulting o-bromoarylcarbamate and reductive radical cyclization of the product with tributyltin hydride/AIBN. 3-Methyleneindolines, as valuable, versatile intermediates, can be transformed into highly functionalized 3-substituted indoles by ene-type reactions using different enophiles. Thus, fluoro-, trifluoromethyl- and trifluoromethoxy-substituted diethyl 2-hydroxy-2-[(1H-indol-3-yl)methyl]malonates, ethyl 2-hydroxy-3-(1H-indol-3-yl)propionates and ethyl 2-hydroxy-3-(1H-indol-3-yl)-2-trifluormethylpropionates were obtained in 77-86% yield by simply heating the corresponding tert-butyl 3-methyleneindoline-1-carboxylate with an equimolar amount of diethyl ketomalonate, ethyl glyoxalate and ethyl 3,3,3-trifluoropyruvate, respectively, at 100 °C, without solvent, for 0.5-4 h.     

Synthesis of 3,3′-disubstituted-2,2′-biindolyls through sequential palladium-catalysed reactions of 2,2,2-trifluoro-N-(2-(4-[2,2,2-trifluoro-acetylamino)-phenyl]-buta-1,3-diynyl)-phenyl)-acetamide with organic halides/triflates

Palladium-catalysed reactions of aryl iodides/vinyl triflates with 2,2,2-trifluoro-N-(2-(4-[2,2,2-trifluoro-acetylamino)-phenyl]-buta-1,3-diynyl)-phenyl)-acetamide provide a straightforward entry into 3,3′-disubstituted-2,2′-biindolyls. Subsequent application of the procedure to homochiral aryl iodides affords the corresponding chiral 3,3′-disubstituted-2,2′-biindolyls. The methodology can also be applied to the synthesis of benzo[c]indolo[2,3-a]carbazoles.     

Effects of solvent and base on the palladium-catalyzed amination: PdCl2(Ph3P)2/Ph3P-catalyzed selective arylation of primary anilines with aryl bromides

A readily accessible catalytic system, PdCl₂(Ph₃P)₂/Ph₃P, was developed for the selective arylation of primary anilines with aryl bromides. The strong influence of solvents and bases on the catalytic activity was observed. In refluxing o-xylene, triphenylphosphine shows high efficiency for Pd-catalyzed intermolecular amination reactions. By changing the bases, mono- and diarylation of primary amines could be selectively achieved in high yields. Moreover, the catalytic system showed good toleration for the steric hindrance of anilines. A series of N,N,N′,N′-tetraaryl-1,1′-biphenyl-4,4′-diamines, important intermediates of OLED hole transport materials, were synthesized facilely via coupling reactions between 4,4′-diaminobiphenyls and aryl bromides.     

Pd/C: an efficient, heterogeneous and reusable catalyst for carbon monoxide-free aminocarbonylation of aryl iodides

Carbon monoxide-free aminocarbonylation is carried out efficiently via coupling of N,N-dimethylformamide (DMF) with aryl iodides using Pd/C as a heterogeneous catalyst. The catalyst exhibits remarkable activity and is reusable for up to three consecutive cycles. The reaction is applicable to a wide variety of substituted aryl iodides with different steric and electronic properties providing excellent yields of the corresponding tertiary amides.     

Synthesis of cis-3-arylated cycloalkylamines through palladium-catalyzed methylene sp carbon–hydrogen bond activation

Methylene sp³ carbon–hydrogen bond activation of N-picolinoylcycloalkylamines provides a useful method for synthesizing cis-3-arylated cycloalkylamine derivatives. Pd(II) species catalyzed the γ-arylation of N-picolinoylcycloalkylamines with aryl iodides in the presence of silver carbonate to afford cis-3-arylated N-picolinoylalkylamines in up to 87% yield. Hydrolysis of the amide linkage to give the corresponding cis-3-arylated cycloalkylamines was also demonstrated.