Synthesis of diaryl ketones via a phosphine-free Fukuyama reaction

The synthesis of unsymmetrical diaryl ketones via the Fukuyama coupling of thioesters and organozinc reagents is described. Typically, the synthesis of diaryl ketones using this methodology provides low yields. The simple complex, Pd(dba)(2), was found to convert a variety of aryl thioesters to diaryl ketones in good yields.     

Photochemistry of nonconjugated bichromophoric systems: Photoreductive polyrecombination of diaryl ketones

The irradiation of nonconjugated bichromophoric systems, diaryl ketones, with ultraviolet light in the presence of hydrogen donors, such as isopropanol or bisbenzhydrol, yields high polymers. Two series of arylketones were investigated, namely bisbenzophenones and bisketotriazoles. The cage reaction, which arises from the cross combination between the acetone ketyl and bisbenzophenone ketyl radicals, was estimated to be very small but may constitute a chain termination reaction in the photopolymerization in isopropanol. The photopolymerization of bisdiketone–dihydrol systems was found to yield polymers with much higher molecular weights than those obtained from the photopolymerization of bisdiketone–isopropanol systems. The photolysis of some binary mixtures of aromatic diketones in the presence of isopropanol yielded statistical copolypinacols. In some favorable cases, the NMR spectrum of the copolymer obtained showed three distinct linkages and from the infrared spectrum intensities the copolymers composition and the number average length of the sequences may be determined.     

Ultrafast chemistry: cobalt carbonyl-mediated synthesis of diaryl ketones under microwave irradiation

By combining the advantages of metal activation, in situ carbon monoxide delivery, and microwave heating, benzophenones were efficiently synthesized in 6-10 s. These ultrafast carbonylation reactions occur under air by flash heating of aryl iodides in the presence of dicobalt octacarbonyl. [reaction: see text]     

The conformational spaces of dinaphthyl ketones,dinaphthyl thioketones,and dinaphthyl diazomethanes: 1-substituted naphthalenes versus 2-substituted naphthalenes

1,1′-Dinaphthyl ketone (15), 1,2′-dinaphthyl ketone (18), 2,2′-dinaphthyl ketone (19), 1,1′-dinaphthyl thioketone (16), 1,2′-dinaphthyl thioketone (20), 2,2′-dinaphthyl thioketone (21), 1,1′-dinaphthyldiazomethane (17), 1,2′-dinaphthyldiazomethane (22), and 2,2′-dinaphthyldiazomethane (23) have been synthesized. Ketone 15 has been prepared from di(1-naphthyl)methanol; ketone 18 has been prepared by a Friedel–Crafts acylation of naphthalene with 2-naphthoyl chloride; ketone 19 has been prepared by a Grignard reaction of 2-naphthylmagnesium bromide with 2-naphthoyl chloride. Thioketones 16, 20, and 21 have been prepared by reactions of the corresponding ketones 15, 18, and 19 with Lawesson’s reagent. The diazomethane derivatives 17, 22, and 23 have been prepared by the HgO oxidation of the respective hydrazones 25, 27, and 28 (prepared from the respective thioketones 16, 20, and 21). The crystal and molecular structures of ketones 15, 18, and 19 and of thioketone 16 have been determined. A variety of conformations in the crystal structures is noted: 1Z,1′Z (15), 1E,1′Z (16), 1E,2′E (18), 2Z,2′Z (19). The NMR experiments have demonstrated the downfield shifts of the protons peri to the carbonyl and the thiocarbonyl groups in 15, 16, and 18, but not in 20. A systematic DFT study (B3LYP/6-31G(d)) of the conformational spaces of 15–23 and their ¹H and ¹³C NMR chemical shifts has been performed. In each series of constitutional isomers, the order of stabilities is 2,2′-(NA)₂C=X > 1,2′-(NA)₂C=X > 1,1′-(NA)₂C=X. The decrease in the stabilities of 1-naphthyl derivatives relative to 2-naphthyl derivatives is attributed to the increased overcrowding and the increased twist angles in 1-naphthyl derivatives. The increased stabilization of E-conformations with the increase of the radius of a heteroatom at C⁹ due to the steric reasons is noted. The DFT calculations satisfactorily describe the X-ray conformations of 15, 16, 18, and 19.     

Rhodium-catalyzed direct aldol condensation of ketones: a facile synthesis of fused aromatic compounds

Cationic rhodium complex [Cp^∗Rh(η⁶-C₆H₆)](BF₄)₂ (1) acts as an efficient catalyst for direct aldol condensation of ketones. The method can be applied to one-pot synthesis of fused aromatic compounds from cyclic ketones via sequential C-C bond formations.     

Selective preparation of 1-substituted 2,2-difluoroethenyl phosphates or 1-hydroxyalkanephosphonates through the reaction of chlorodifluoromethyl ketones with dialkyl or diaryl phosphites

Various chlorodifluoromethyl ketones react readily with dialkyl or diaryl phosphites in the presence of triethylamine at the reflux temperature of tetrahydrofuran to give the corresponding dialkyl or diaryl 1-substituted-2,2-difluoroethenyl phosphates in good yields, whereas the similar reaction conducted at lower temperature (0-20 °C) affords 1-(chlorodifluoromethyl)-1-hydroxyalkanephosphonates almost exclusively. The latter compounds are converted to the former enol phosphates by the treatment with triethylamine or sodium methoxide in refluxing tetrahydrofuran.     

Diinsertion of fluorenylidene into a sulfur-sulfur bond of diaryl disulfides

Upon irradiation (>340 nm) of a benzene solution of diazofluorene with di-p-tolyl- or di-p-anisyl disulfide, the corresponding 9,9′-bis(arylmercapto)bifluorenyl was afforded in moderate to good yield accompanied by formation of 9,9′-bis(arylmercapto)fluorene. The major reaction pathway is considered to be a disulfur ylide formation followed by two times of successive Stevens rearrangement or by concerted electron redistribution via [2,3]sigmatropic rearrangement.     

Intermolecular interactions: Elaboration on an additive procedure including an explicit charge-transfer contribution

An additive procedure is derived for the computation of intermolecular interactions, in which an explicit expression for the charge-transfer energy contribution E_CT is implemented. In the total interaction energy, the electrostatic terms E_MTP and E_pol are calculated as in our previous treatment. The dispersion contribution is calibrated by reference to variation-perturbation computations on model systems and the repulsion contribution is computed as a sum of bond—bond, bond—lone pair, and lone pair—lone pair interactions. Tests of the procedure are given for representative hydrogen-bonded systems.     

An atom-efficient palladium-catalyzed cross-coupling reaction of triarylbismuths with acid chlorides: synthesis of diaryl and alkyl aryl ketones

The cross-coupling reaction of triarylbismuths with acid chlorides using a catalytic amount of PdCl₂/PPh₃ afforded the corresponding ketones in high yields. The reactions of aromatic and aliphatic acid chlorides occurred with atom efficiency, as 3 equiv of acid chlorides coupled effectively with 1 equiv of triarylbismuths to yield 3 equiv of the corresponding diaryl and alkyl aryl ketones.     

Directly fused highly substituted naphthalenes via Pd-catalyzed dehydrogenative annulation of N,N-dimethylaminomethyl ferrocene using a redox process with a substrate

N,N-Dimethylaminomethyl ferrocenium could be generated in situ and served as a terminal oxidant for Pd-catalyzed directly dehydrogenative annulations of N,N-dimethylaminomethyl ferrocene and internal alkynes. This procedure utilized the redox activity of ferrocene and avoided adding an oxidant. A series of highly arylated naphthalenes functionalized by ferrocene were obtained in 53-81% yields.     

Asymmetric addition of achiral organomagnesium reagents or organolithiums to achiral aldehydes or ketones: a review

The enantioselective preparation of chiral secondary and tertiary alcohols via addition of an achiral organomagnesium reagent or an organolithium to an achiral aldehyde or ketone in a chiral medium is reviewed. The review is written in chronological order and contains 113 references to literature through late 2008.     

Ambiguous origin: two sides of an ephrin receptor tyrosine kinase

The assembly of a functional receptor tyrosine kinase via expressed protein ligation using receptor segments produced in two different organisms by Singla et al. (2011) provides a tool for monitoring the order of tyrosine phosphorylation events upon ligand activation.     

Study on the reactivity of diarylmethane derivatives in supercritical alcohols media: reduction of diarylmethanols and diaryl ketones to diarylmethanes using supercritical 2-propanol

We found that diarylmethanols and diaryl ketones were smoothly reduced to the corresponding diarylalkanes using supercritical 2-propanol in good yields. Furthermore, we determined the specific reaction of fluorene using supercritical methanol at high temperature.     

Replacement of a carbonyl group of cyclic ketones by an oxygen atom: A four-step transformation of cyclic ketones into cyclic ethers

We describe a new and versatile method for transforming cyclic ketones into cyclic ethers with the same ring size in which the chirality adjacent to the carbonyl group of the ketones is retained.     

Tandem reactions of α-diazo ketones with macrocyclic olefins: diastereoselective synthesis of oxanorbornane fused macrocyclic lactones

Tandem cyclization-cycloaddition reactions of α-diazo ketones with macrocyclic olefins in the presence of rhodium(II) acetate catalyst led to the oxanorbornane fused macrocyclic di- or tetralactone ring systems in moderate yield. This forms the first example of 1,3-dipolar cycloaddition reactions with a macrocyclic olefin as a dipolarophile, affording a variety of new oxanorbornane fused macrocycles with diastereoselectivity.     

[2 + 2] Cycloaddition of phosphaalkenes as a key step for the reductive coupling of diaryl ketones to tetraaryl olefins

Procedures for the reductive coupling of carbonyl compounds to alkenes in the literature rely either on a radical coupling strategy, as in the McMurry coupling, or ionic pathways, sometimes catalysed by transition metals, as in more contemporary contributions. Herein, we present the first example of a third strategy that is based on the [2 + 2] cycloaddition of ketone-derived phosphaalkenes. Removal of P-trimethylsilyl groups at the intermediary 1,2-diphosphetane dimer results in its collapse and concomitant release of the tetraaryl-substituted alkene. In fact, the presented strategy is the only alternative to the McMurry coupling in the literature that allows tetraaryl alkene formation from diaryl ketones, with yields as high as 85%. The power of the methodology is illustrated in the reaction of tethered bis-benzophenones which engage in intramolecular reductive carbonyl couplings to form unusual macrocycles without the need for high dilution conditions or templating.

Mechanistically distinct from all other carbonyl-to-alkene conversion methodologies, the [2 + 2] cycloaddition of phosphaalkene intermediates is established as the enabling elementary step in this transformation.     

Hydrazine hydrate induced reductive cleavage of α,β-epoxy ketones: an efficient procedure for the preparation of β-hydroxy ketones

An efficient and general procedure for the reductive cleavage of α,β-epoxy ketones to the corresponding β-hydroxy ketones, using hydrazine hydrate in ethanol at low temperatures, is described.     

Elaboration of D-(-)-ribose into a tricyclic, natural product-like scaffold

The construction of natural product-like, tricyclic compounds is reported. Starting from a D-(-)-ribose-derived dihydrofurane, the tricyclic scaffold is prepared via an intramolecular hetero-Diels-Alder reaction. The reaction proceeds with very high diastereoselectivity through an endo transition state, as established on the basis of X-ray structural analysis of the products. Further modification and derivatization of the obtained products is described.     

Heteroatom as a promotor: synthesis of polyfunctionalized benzenes and naphthalenes

Construction of a new benzene via the electrocyclization of diene-allene is an efficient protocol to access polysubstituted benzenes from simple, readily available starting materials. In this paper, we present a comprehensive study of a heteroatom-promoted propargyl-allenyl isomerization and electrocyclization for the facile and efficient synthesis of polyfunctionalized benzenes and naphthalenes. As a result of the readily accessible starting materials, simple operation, and mild conditions, this reaction should be an appealing strategy in organic synthesis.