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.     

Diels-Alder reaction of 4-halogenated masked o-benzoquinones with electron-rich dienophiles

Inverse-electron-demand Diels-Alder reaction of masked o-benzoquinones (MOBs) ensuing from the corresponding 4-halo-2-methoxyphenols with styrene, dihydrofuran and ethyl vinyl ether, butyl vinyl ether, phenyl vinyl sulfide and vinyl acetate to afford the highly functionalized halogen substituted bicylclo[2.2.2]octenones are described.     

The reaction of o-nitro- and p-nitro-phenyl selenocyanates with arylthiols

The interaction of o-nitro- and p-nitro-phenyl selenocyanate with aromatic thiols p-thiocresol, p-chlorothiophenol, 4-bromothiophenol, o-mercaptobenzoic acid and pentafluorothiophenol in non-aqueous media and under an atmosphere of dry nitrogen has been investigated. The main products are the diselenide or the selenenyl sulphide depending on the reactants. Hydrogen cyanide is given in all cases. The IR and Raman spectra of the diselenides and selenenyl sulphides are considered.     

A novel aromatic alkylation of anilines with cyclic and acyclic ketones under hydrothermal conditions

A novel aromatic ring-alkylation was achieved by condensation between aniline·HCl salts and cyclic or acyclic ketones under hydrothermal conditions.     

The reaction of allyldialkyltelluronium bromides with anilines

Allyldialkyltelluronium bromides were treated with aromatic amines in 1,2-dichloroethane, readily giving allyl aryl amines in excellent yields.     

An efficient, high yielding protocol for the synthesis of functionalized quinolines via the tandem addition/annulation reaction of o-aminoaryl ketones with α-methylene ketones

A mild and efficient method has been developed for the condensation of 2-aminoaryl ketones with α-methylene ketones in the presence of a catalytic amount of reusable catalyst CeCl₃·7H₂O (25 mol %) at ambient temperature to afford the corresponding poly-substituted quinolines in high yields under mild conditions.     

Synthesis of C1-symmetric chiral tripodal oxazolines through an oxazoline exchange reaction with amino alcohols

Various C₁-symmetric chiral tripodal tris(oxazolines) with two different oxazoline units were synthesized from chiral C₃-symmetric tris(oxazolines) through an oxazoline exchange reaction with amino alcohols in the presence of zinc chloride. Evaluation of the new oxazolines as chiral molecular receptor showed that some of the receptors have chiral discrimination ability.     

Chiral phosphoric acid-catalyzed enantioselective three-component Mannich reaction of acyclic ketones,aldehydes and anilines

1. Download high-res image (111KB)
2. Download full-size image

     

Oxidative addition reaction of o-quinones to triphenylantimony: novel triphenylantimony catecholate complexes

New catecholate Sb(V) complexes triphenyl(3,6-di-tert-butylcatecholato)antimony(V) Ph₃Sb(3,6-DBCat) (1) and triphenyl(perchloroxanthrenecatecholato)antimony(V) Ph₃Sb(^OXCat_Cl) (2) were synthesized by the oxidative addition reaction of corresponding o-quinones (3,6-di-tert-butyl-o-benzoquinone and perchloroxanthrenequinone-2,3) with triphenylantimony. Catecholates 1 and 2 can alternatively be synthesized by reacting the appropriate thallium catecholate with triphenylantimony dichloride. The oxidative addition reaction of an equimolar ratio of 4,4′-di-(3-methyl-6-tert-butyl-o-benzoquinone) and triphenylantimony yielded 4-(2-methyl-5-tert-butyl-cyclohexadien-1,5-dion-3,4-yl)-(3-methyl-6-tert-butyl-catecholato)triphenylantimony(V) Ph₃Sb(Cat-Q) (3); in the case of a 1:2 molar ratio, complex 4,4′-di-[(3-methyl-6-tert-butyl-catecholato)triphenylantimony(V)] Ph₃Sb(Cat-Cat)SbPh₃ (4) resulted. Complexes 1-4 were characterized by IR- and ¹H NMR spectroscopy. Molecular structures of 1, 2 and 4 were determined by X-ray crystallography to be a distorted tetragonal-pyramidal.     

A novel pyrrole synthesis via reaction of ketones with N-aminoimides

A new, mild synthesis of pyrroles using N-aminoimides and a ketone is described. The reaction has been utilized in the synthesis of dimeric morphinans containing a connecting pyrrole ring. The reaction appears to proceed through a diacylhydrazone intermediate, and it is suggested that the driving force behind the reaction is the facility with which a protonated imide moiety operates as a leaving group.     

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.     

Pd(II)-catalyzed coupling-cyclization reaction of o-ethylnylphenylphosphonamides monoesters with allyl halide

4-Allyl-phosphaisoquinolin-1-ones were synthesized by palladium-catalyzed coupling-cyclization of o-ethynylphenylphosphonamide monoethyl esters with allyl halides with high regioselectivity and good yields. The synthesized 4-allyl-phosphaisoquinolin-1-ones show bioactivity as inhibitor of MCH-1R.     

NiCl2-catalyzed cascade reaction of isocyanides with functionalized anilines

A NiCl₂-catalyzed isocyanide insertion reaction of anilines bearing another nucleophile functional group utilizing TEMPO as oxidant in isopropyl ethanoate (IPA) or THF has been reported. This simple and general method could afford 2-aminobenzimidazole, 2-aminobenzothiazole, 2-aminobenzoxazole, as well as 2-aminobenzo[d][1,3]oxazine in moderate to excellent yields (up to 95% yield).     

The gomberg-bachmann reaction for the arylation of anilines with aryl diazotates

Simply aqueous sodium hydroxide is sufficient to exclude ionic side reactions and to prepare 2-aminobiphenyls from aryl diazotates and anilines through a new variant of the Gomberg-Bachmann reaction. The metal-free reaction under basic conditions allows to exploit the highly radical-stabilizing effect of the aniline's free amino function for the first time, which leads to a so far unreached regioselectivity.     

A facile three-component reaction of dicarbomethoxycarbene, aldehydes and o-quinones: synthesis of novel spiro-dioxolanes

Successful trapping of the carbonyl ylides generated from dicarbomethoxycarbene and aldehydes with 1,2-diones is described.     

The reaction of terminal α-acetylenic ketones with thiosemicarbazones

The reaction of terminal -acetylenic ketones with thiosemicarbazones gives a series of 5-amino-and 5~anilino-3-acylvinyl-⁴-1,3,4-thiadiazolines. These products react with perchloric acid to give the corresponding perchlorates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1176–1179, May, 1990.     

Carbonylative Sonogashira annulation sequence: One-pot synthesis of 4-quinolone and 4H-chromen-4-one derivatives

Carbonylative Sonogashira annulation sequence for one pot synthesis of 4-quinolone and 4H-chromen-4-one has been developed in presence of Pd-NHC catalyst. Substituted 2-iodoaniline and 2-iodophenol independently underwent in the carbonylative Sonogashira annulation reaction with a variety of acetylenes to result in 4-quinolone and flavone derivatives respectively in good to excellent yield. Moreover, this protocol does not require toxic CO gas, high catalyst loading and any expensive salt/additive. Herein we, for the first time, are using Mo(CO)₆, as solid CO source for the one pot synthesis of flavone derivatives via carbonylative Sonogashira annulation reaction.     

Halogenation of ketones with N-halosuccinimides under solvent-free reaction conditions

Several aryl substituted ketones, cyclic ketones, 1,3-diketones and a β-ketoamide were halogenated with N-halosuccinimides under solvent-free reaction conditions (SFRC) at various temperatures (20-80 °C), whereas less enolized ketones required the presence of an acid catalyst (p-toluenesulfonic acid, PTSA). Bromination of substituted acetophenones obeys first order kinetics v=k_Br[ketone] and the following correlation with the keto-enol equilibrium constant: log k_Br=0.3pK_E+C₁, less enolized substrates being more reactive; the moderate positive charge developed in the rate determining step was confirmed by the Hammett correlation (ρ=−0.5). On the other hand, in cyclic ketones an opposite relation was observed: log k_Br=−0.6pK_E+C₂, indicating higher reactivity of substrates with higher enolization constant (K_E). The important role of the nature of the solvent (MeCN, MeOH) in preorganization of the ketone-NBS-PTSA mixture prior to SFRC bromination was found.