Tributyltin Aryl Selenides as Efficient Arylselenating Agents. Synthesis of Diaryl and Aryl Organyl Selenides

Tributyltin aryl selenides are highly efficient arylselenating agents in reactions with aryl iodides and aryl triflates under catalysis with Pd and Ni complexes respectively. They also may be used as efficient source of active arylselenolate anion in the presence of fluoride ions in reaction of arylselenation of alkyl halides and activated aryl fluorides.     

Polyfluorocycloalkenes. Part XVIII. Aryl adducts of decafluorocyclohexene

Decafluorocyclohexene reacted slowly with aniline to give 1-phenylamino- 3-phenyliminoheptafluorocyclohex-2-ene, which was hydrolysed by hydrochloric acid to 3-phenylaminoheptafluorocyclohex-2-enone. Decafluorocyclohexene reacted stepwise with phenyl lithium, giving 1-phenylnonafluorocyclohexene and thence 1,2-diphenyloctafluorocyclohexene: the former product was attacked slowly by pentafluorophenyl lithium at ?40°C affording 1-pentafluorophenyl- 1-phenyloctafluorocyclohexene. Phenyl lithium reacted sluggishly with bis(pentafluorophenyl)octafluorocyclohexene to give 1-pentafluorophenyl-2-(2′,3′,5′,6′-tetrafluoro-1′-biphenylyl)octafluorocyclohexene and 1,2-bis(2′,3′,5′,6′-tetrafluoro-1′-biphenylyl)octafluorocyclohexene. 1,2-Diphenyloctafluorocyclohexene and 1,2-bis(pentafluorophenyl) octafluorocyclohexene were fluorinated by cobalt(III) fluoride to give the olefin, 1,2-bis(undecafluorocyclohexyl)octafluorocyclohexene.     

CuI-catalyzed Synthesis of Aryl Thiocyanates from Aryl Iodides

Aryl thiocyanates are important compounds not only for their interesting biological properties, but also because of their use as a versatile starting material for many sulfur- containing aromatic compounds, including sulfonyl cyanides, sulfonic acids, sul…     

Visible-Light-Induced Palladium-Catalyzed Generation of Aryl Radicals from Aryl Triflates

A mild visible-light-induced Pd-catalyzed intramolecular C−H arylation of amides is reported. The method operates by cleavage of a C(sp²)−O bond, leading to hybrid aryl Pd-radical intermediates. The following 1,5-hydrogen atom translocation, intramolecular cyclization, and rearomatization steps lead to valuable oxindole and isoindoline-1-one motifs. Notably, this method provides access to products with readily enolizable functional groups that are incompatible with traditional Pd-catalyzed conditions.     

Photohomolysis and Photoheterolysis in Aryl Sulfonates and Aryl Phosphates

The photochemical behaviour of selected aryl sulfonates and phosphates (ArOX) in polar and nonpolar media has been investigated by laser flash photolysis (LFP) experiments. Two main pathways have been identified, namely the photohomolysis of the ArO−X bond or the photoheterolysis of the Ar−OX bond depending on the nature of the leaving group (OX) and on the nature of the substituents on the aromatic ring. In nonpolar solvents the esters are quite photostable due to an efficient triplet deactivation. In polar solvents, the homolytic fragmentation of the ArO−S bond from the exited singlets was found in aryl sulfonates bearing moderately electron-donating groups as well as electron-withdrawing groups. In electron-rich aryl phosphates and sulfonates photoheterolysis of the Ar−OP/Ar−OS bond took place as the exclusive pathway.     

Aryl coupling through borate complexes with ethanolamine.

The scope and limitations of aromatic coupling by the action of N-bromosuccinimide on stable diarylethanolamine borate salts are disclosed. The procedure is an excellent, regiospecific procedure for the coupling of furyl and thienyl residues to each other or to aromatic rings in mild conditions and without scrambling.     

芳甲酸氰基芳甲酯的合成

芳甲酸氰基芳甲酯是重要的有机合成中间体,其现有合成方法采用剧毒氰化物为氰源来合成。 本研究以K₄[Fe(CN)₆]为绿色氰化试剂,芳酰氯为原料,采用一锅两步反应合成芳甲酸氰基芳甲酯。 通过改变第二步反应温度、反应时间、硼氢化钠和催化剂的用量获得最佳反应条件,以61.7%~80.3%的产率合成了10种芳甲酸氰基芳甲酯(2a~2j),产物结构通过傅里叶变换红外光谱仪(FTIR)、核磁共振波谱仪(NMR)分析确认。 根据实验结果,提出了可能的反应机理。 该法避免了对剧毒氰化剂的使用,具有产率高、操作简单、后处理方便等优点。     

Photophysics and photostereomutation of Aryl methyl sulfoxides.

The effect of a methanesulfinyl group on the photophysics of several aromatic chromophores is reported. The spectroscopic singlet and triplet energies are affected only modestly, compared to that parent arenes, but the fluorescence yields fall by at least 1 order of magnitude. Fluorescence lifetimes are short. Fluorescence enhancements are observed on cooling the sulfoxides from room temperature to 77 K. High quantum yields of stereomutation are reduced as the temperature drops. There is not a consistent effect on triplet or phosphorescence yields. It is proposed that these results are consistent with a nonradiative pathway for deactivation of the singlet that results in stereomutation. A modest activation energy of a few kcal/mol is estimated for the photochemical racemization of 1-methanesulfinylpyrene.     

Palladacycle-Catalyzed Carbonylation of Aryl Iodides or Bromides with Aryl Formates

An efficient palladacycle-catalyzed aromatic carbonylation reaction of aryl formates with aryl iodides or bromides has been developed. Commercially available and easily prepared aryl formates were employed as carbonyl sources without the use of external carbon monoxide. The present catalytic system shows broad functional group tolerance and affords aryl benzoate derivatives in good to excellent yields.     

Aryl trifluoromethyl acetylenes

A wide variety of aryl trifluoromethyl acetylenes may be prepared in high yield by allowing CF₃CCZnCl, generated from CF₃CCH, to react with aryl iodides a catalytic amount of tetrakis(triphenylphosphine)-palladium.     

Aryl aminoalkyl sulfones

Two methods are proposed for the preparation of aryl aminoalkyl sulfones substituted in the aromatic ring: a method based on the oxidation of aryl aminoalkyl sulfides by hydrogen peroxide or of their bases in the presence of HClO₄ and a method based on the oxidation of aryl -chloroalkyl sulfides to chlorosulfones by hydrogen peroxide followed by their condensation with amines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2580–2585, November, 1989.     

C-Glycosylated Aryl Tins: Versatile Building Blocks for Aryl C-Glycoside Glycomimetics

ABSTRACT

C-glycosylated aryl tins have been prepared as versatile building blocks of physiologically stable glycomimetics for glycoepitopes that have been recognized to serve biologically important roles in cell biochemistry.     

钨酸钠催化芳香腈高选择性氧化制备芳香酰胺

 The preparation of aryl amides by selective oxidation of aryl nitriles using sodium tungstate as catalyst and sodium percarbonate or sodium carbonate-hydrogen peroxide as the oxidant in a methanol and water solution was studied. Aryl nitriles were converted to aryl amides with very high selectivity of 95%～100% at room temperature. The reactivity of aryl nitriles decreased with increasing their branched chain length. In the oxidation of tolunitriles, the oxidation rate of p-tolunitrile and m-tolunitrile was very fast, but the oxidation rate of o-tolunitrile was very slow. The oxidation rate of p-haloid aryl nitriles and p-nitro aryl nitrile decreased in the order p-nitrobenzonitrile＞p-chlorobenzonitrile＞p-bromobenzonitrile, while the selectivity for aryl amides was maintained at a high level of 98%～100%. The comparison of the two oxidants showed that when sodium carbonate-hydrogen peroxide was used as oxidant, the oxidation rate and selectivity were better than that when percarbonate was used. The sodium tungstate catalyst and carbonate can be reused and the catalytic activity and selectivity did not change if a suitable amount of hydrogen peroxide was supplied. This work provides a convenient method for the preparation of aryl amides from aryl nitriles under very mild reaction conditions.     

LiCl-Accelerated Nickel Catalyzed Cross-Coupling of Aryl Tosylates with the Aryl Grignard Reagents

Russian Journal of General Chemistry - A mild coupling reaction catalyzed by Ni(acac)2-L4 has been studied. The catalyst acts efficiently in the reaction of biaryl coupling between various...     

Dehydration of Aryl Aldoximes

The conversion of aldoximes into nitriles is a well known, straightforward and important organic operation which may be brought about by the action of common dehydrants such as acetic anhydride¹ and mesyl chloride^2. This paper describes a new method of effecting the reaction.