59485-34-6

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The realization of photocatalysis for practical synthetic application hinges on the development of inexpensive photocatalysts which can be prepared on a large scale. Herein an air-stable, visible-light-absorbing photoluminescent tungsten(vi) complex which can be conveniently prepared at the gram-scale is described. This complex could catalyse photochemical organic transformation reactions including borylation of aryl halides, such as aryl chloride, reductive coupling of benzyl bromides for C-C bond formation, reductive coupling of phenacyl bromides, and decarboxylative coupling of redox-active esters of alkyl carboxylic acid with high product yields and broad functional group tolerance.

The invention discloses a method for preparing organic carboxylic ester by combined catalysis of an aryl bidentate phosphine ligand. The method comprises the following steps: under the action of a palladium compound/aryl bidentate phosphine ligand/acidic additive combined catalyst, carrying out a hydrogen esterification reaction on terminal olefin, carbon monoxide and alcohol so as to generate theorganic carboxylic ester with one more carbon than olefin. According to the invention, by adoption of the palladium compound/aryl bidentate phosphine ligand/acidic additive combined catalyst, good catalytic activity and selectivity for the hydrogen esterification reaction of the olefin are achieved, and olefin carbonylation to synthesize organic carboxylic ester can be efficiently catalyzed. Thearyl bidentate phosphine ligand has a rigid skeleton structure of a rigid ligand and the flexibility of a flexible ligand, so the aryl bidentate phosphine ligand has proper flexibility due to the characteristic that the aryl bidentate phosphine ligand is soft and rigid, and a most favorable coordination mode and a stable active structure in space are favorably formed. In addition, the aryl bidentate phosphine ligand has the advantages of high stability, simple and convenient synthesis method and the like; and a novel industrial technology is provided for production of organic carboxylate compounds.

The invention relates to a preparation method of bibenzyl compounds. A compound represented by a formula (A) and a compound represented by a formula (C) carry out reactions under the action of an organic tungsten catalyst and an alkali in the presence of light to generate bibenzyl compounds represented by the formula (B). The method is simple and is easy to operate. The yield is high, and the application range is wide. Moreover, the invention also provides an application of a tungsten complex in organic chemical reactions as a photocatalyst.

The invention relates to oligomerization of olefins, such as ethylene, to higher olefins, such as a mixture of 1-hexene and 1-octene, using a catalyst system that comprises a) a source of chromium b) one or more activators and c) a phosphacycle-containing ligating compound. Additionally, the invention relates to a phosphacycle-containing ligating compound and a process for making said compound.

Benzyl and allyl halides undergo homocoupling when treated with zinc in the presence of a catalytic amount of a cationic iridium(III) complex under irradiation with 400 nm light-emitting diodes. The reaction proceeds through the intermediate formation of an organozinc reagent, which disproportionates to a free radical and elemental zinc under photoredox conditions.

The use of heterogeneous bimetallic Pd-based nanocatalyst for directing the inactivated sp3 C?H coupling has been scarcely explored. This work reported the formation of symmetrical C?C bonds from the inactivated sp3 C?H bonds catalyzed by employing reduced graphene oxide supported PtPd@Pt porous nanospheres. The reaction of sp3 C?H activation proceeded under mild conditions without any solvent, ligand or directing group. It is a higher atom-, step- and cost-effectiveness strategy for developing heterogeneous catalysts in the synthesis of bibenzyls with various functional groups (e. g. aryl, alkyl, methoxyl, halogen, ester, and pyridyl). (Figure presented.).

Cyclopentadienyl (Cp) Ni(ii) complexes [CpNiL][PF6] containing hybrid N,C chelating benzothiazolyl NHC ligands (L1 = 1-(2-benzothiazolyl)-3-methylimidazol-2-ylidene, 3a; L2 = 1-(2-benzothiazolyl)-3-allylimidazol-2-ylidene, 3b; L3 = 1-(2-benzothiazolyl)-3-benzylimidazol-2-ylidene, 3c) have been synthesized and fully characterized. The catalytic activity of 3a-3c in some C-C bond formation reactions has been examined. They are efficient catalysts for the homo-coupling of benzyl bromide in the presence of MeMgCl at r.t. with good functional group tolerance. Complex 3a is active in the catalytic oxidative homo-coupling of Grignard reagents with 1,2-dichloroethane as an oxidant at r.t.

Herein, we report the first catalytic version of a cobalt-catalysed reductive homocoupling of benzyl halides which proceeds with low catalyst loadings (0.5 to 5 mol%). By synthetizing each cobalt intermediate we demonstrate that reaction proceeds through two single electron transfers (SET) and that dimethylzinc is only involved in the regeneration of the catalytic species.

Novel dibenzosuberane-based compounds, compositions containing such compounds, and electronic devices containing such compounds as electron transport materials are described herein. Methods for making the dibenzosuberane-based compounds of the present invention are also described.

A highly reactive alkylrhodium complex was formed from Me2Zn and RhCl(PPh3)3 and effectively catalyzed a Csp 3-Csp3 homocoupling reaction of benzyl halides. A Csp 3-Csp3 coupling reaction using Rh catalyst has not been reported up to now. The reaction proceeded under very mild conditions and gave the corresponding homocoupling products even if they had reactive substituents such as an uncovered formyl or hydroxymethyl group.

The C-C bond formation by homogeneous catalysis is a powerful tool in organic synthesis. The replacement of noble metal by cheaper one for already reported methodologies is of interest for an economical purpose. The attractivity of such replacement is also enhanced if a first raw transition metal is found to be active in several processes. This work demonstrates that a common nickel complex can be used for a two-step cross-coupling procedure, namely a homocoupling reaction of benzyl derivatives and a subsequent Suzuki reaction. These consecutive reactions permit the synthesis of new polyfunctionalized dibenzyl compounds.

2-Aminoethyl diphenylborinate (2-APB) is a known modulator of the IP 3 receptor, the calcium ATPase SERCA, the calcium release-activated calcium channel Orai and TRP channels. More recently, it was shown that 2-APB is an efficient inhibitor of the epithelial calcium channel TRPV6 which is overexpressed in prostate cancer. We have conducted a structure-activity relationship study of 2-APB congeners to understand their inhibitory mode of action on TRPV6. Whereas modifying the aminoethyl moiety did not significantly change TRPV6 inhibition, substitution of the phenyl rings of 2-APB did. Our data show that the diaryl borinate moiety is required for biological activity and that the substitution pattern of the aryl rings can influence TRPV6 versus SOCE inhibition. We have also discovered that 2-APB is hydrolyzed and transesterified within minutes in solution.

Let the sunshine in! Unactivated alkyl and aryl bromides underwent a light-enabled reductive radical cyclization in the presence of a dimeric phosphine-gold complex as a photocatalyst (see scheme; X=C(CO 2Et)2, NR, O). Sunlight can be used as the energy source for this simple and efficient radical reaction, which does not require potentially hazardous and toxic chemical reagents, such as organostannanes and chemical initiators.

Simple and straightforward coupling of benzylic compounds was achieved by sonicating benzylic halides in the presence of magnesium.

A continuous flow protocol for the preparation of the tricyclic antidepressant (TCA) amitriptyline is reported. The advantages of flow chemistry when handling organometallic agents as well as when performing reaction with gases are demonstrated. Continuous multilithiation combined with carboxylation and the Parham cyclization, a Grignard addition and thermolytic water elimination by inductive heating are key features of the multistep protocol. Copyright

Several chiral thiepines were efficiently constructed using sulfur diimidazole in combination with a variety of bislithiated carbon fragments. The sulfur atom in these thiepines is found to be unusually unreactive compared to diphenylsulfide. The Royal Society of Chemistry 2006.

A wide range of organozinc substrates may be oxidized in the presence of catalytic copper to give carbon-carbon bonds in high yield. The Royal Society of Chemistry 2006.

(Chemical Equation Presented) Iron-catalyzed homo-coupling of simple and functionalized arylmagnesium reagents is described. The reaction is highly chemoselective (CN, COOEt and NO2 groups are tolerated). The procedure was used to perform intramolecular couplings. This cyclization reaction is the key step of the total synthesis of the N-methylcrinasiadine.

(Matrix Presented) A novel palladium-catalyzed coupling reaction between two Csp3-Csp3 centers has been investigated. This protocol is initiated by the oxidative addition of an α-halo carbonyl compound to a palladium(0) species, followed by the double transmetalation. The key dialkyl palladium intermediate undergoes reductive elimination to form the desired coupling product.

Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E, E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.

The preparation of the title compounds is greatly improved by combining seven steps (three lithiations, three substitutions and an oxidation) into a one-pot procedure. The hydrolysis of the related phosphonium salts, the lithiation of the P-propyl phosphepine oxides and their reaction with electrophiles are described.

Cyclobenzylation of 2-hydroxymethyldiphenylethanes 4 and 2,2'-bis(hydroxymethyl)diphenylethanes 13 in the presence of a solid perfluorinated sulfonic acid resin, Nafion-H, as a catalyst results in novel polycyclic aromatic hydrocarbons, dibenzocyclopentenes.Dibenzocyclopentenes were also prepared from diphenylethanes by a benzylation reaction, which incorporates chloromethylation of a hydrocarbon followed by Friedel-Crafts intramolecular cyclization reaction.The present method involving the action of ClCH2OMe and TiCl4 on a variety of diphenylethanes (constructed such that electrophilic substitution occurs ortho to the diphenylethane linkage) offers a convenient, mild one-pot synthesis of substituted dibenzocycloheptenes.The mechanism of these reactions is also discussed.

Flash vacuum pyrolysis over magnesium at 600°C results in efficient dehalogenation of a variety of organic halides and provides a preparatively useful method for C-C bond formation and other reactions.

The reaction of benzyl bromide with bis-(N- and C-ortho)-lithiated chloroanilides 4, 5, and 6 has been examined.It has been found that in the case where the lithiated compound was derived from meta-methoxyanilides, pre-addition of LiBr or TMEDA was required to achieve C-benzylation.These results were accounted for by the conversion of the usually formed dimer into a mixed dimer with the LiBr or TMEDA complex in which the C-lithium bond appears to be more accessible towards electrophiles.The practical synthesis of o-benzylchlorobenzoic acids 10, 11, and 12 was accomplished via ionic reductive cleavage (Et3SiH/TiCl4) of the corresponding phthalides 18, 19, and 20.The acids 10, 11b, and 11c afforded the corresponding anthrones, upon treatment with trifluoroacetic anhydride which were oxidized by chromium trioxide to the new chloroantraquinones 21, 22, and 23. - Keywords: Chlorophthalides; Reduction; Benzylation; Benzylbenzoic acids; Chloroantraquinones

The combination of palladium-catalyzed intramolecular biaryl coupling with enantioselective dihydroxylation of achiral stilbenes provides an efficient, two-step route to the chiral 9,10-dihydrophenanthrenediol unit of the pradimicins and benanomicins.

Benzylic Grignard reagents (2)-(4), bearing ortho- and para-halogeno ring substituents, are readily accessible by treating the corresponding benzylic halide with (1) in tetrahydrofuran (thf); o- and p-chloromethyl(methoxymethyl)benzenes with (1) rapidly yield 'di-Grignards' whereas the meta-isomer only affords a mono-Grignard' (5), and bis(methoxymethyl)benzenes slowly undergo C-O cleavage, (6).

The reaction of a series of bis- derivatives P2 with some benzyl halides, trans-1,2-dibromoethane and several heteroaromatic cations Q+ was investigated in acetonitrile/toluene with electrochemical and kinetic methods.For substrates with a reduction potential between -0.9 and -1.5 V the reaction occurs via the ratedetermining dissociation of P2 into free radicals P. as the real reducing agents, which transform the benzyl halides into the corresponding 1,2-diarylethanes and Q+ into the corresponding dimeric product Q2.For thereduction of trans-1,2-dibromocyclohexane to cyclohexene a simultaneous transfer of two electrons to the substrate combined with the dissociation of P2 into two pyridinium ions P+ is proposed.In the case of a reduction potential more positive than -0.9 V (e.g. nitro substituted benzyl halides) P2 itself can act as the reducing agent with an increased reaction rate.With pyrylium ions Q+ a product P-Q was detected by voltammetry and mass spectroscopy.In this case an electrophilic attack onto P2 instead of the electron transfer from P2 to Q+ cannot be excluded.

The reactions of (o-diphenylphosphinobenzyl)dimethylsilane with manganese and rhenium carbonyl afford o-(C6H5)2PC6H4CH2Si(CH3)2M(CO)4 (M=Mn, Re), in which the ligand behaves as a chelate.Similar reactions occur with ?-cyclopentadienemolybdenum tricarbonyl dimer to give o-(C6H5)2PC6H4CH2Si(CH3)2Mo(?-C5H5)(CO)2.However, photolysis of a mixture of the ligand with manganese carbonyl yielded o-(C6H5)2PC6H4CH2Si(H)(CH3)2Mn2(CO)9.

Direct reaction of 2,2′-dilithiobibenzyl with (CH3)2MCl2 or (C6H5)2MCl2 where M Si, Ge, Sn, or Pb results in the formation of 10,11-dihydro-5H-dibenzo-[b,f]metallepins. The germanium derivaives were successfully converted to 5,5-dimethyl- and 5,5-diphenyl-5H-dibenzo[b,f]germepin by bromination followed by dehydrobromination with 1,5-diazabicyclo[4.3.0]non-5-ene. Reactions of dihydrodibenzo[b,f]stannepins uniformly gave ring cleavage products. The abundances of the metal fragments produced in the mass spectrum of the dihydrodibenzometallepins are recorded and a fragmentation pattern common to the system is given.