Photochemical preparation and rearrangement of some symmetrical methoxypyridyl phenyl glycols (pinacols)

Solutions of 6-methoxy-3-pyridyl phenyl ketone and 3-, 4-, 5- and 6-methoxy-2-pyridyl phenyl ketones in isopropyl alcohol were subjected to ultraviolet radiation. All the ketones except 3-methoxy-2-pyridyl phenyl ketone were observed to undergo bimolecular reduction to give the corresponding pinacols in 30-100 percent yields. In cold concentrated sulfuric acid the pinacols were found to rearrange with the exclusive migration of the phenyl group. The pinacols hearing the 3-pyridyl groups rearranged at a much faster rate than the 2-pyridyl isomers.     

多重氢键自组装联萘酚和含氮化合物

作为相互识别的结果,(±)-2,2′-二羟基-1,1′-联萘酚可与4,4′,6,6′-四甲基-2,2′-联嘧啶、1,2-双(4-吡啶)乙烷、反式-1,2-双(4-吡啶)乙烯、4,4′-联吡啶-N,N′-双氧化物及双-2-吡啶基甲酮等多种含氮化合物分别形成外形良好的共晶化合物1,2,3,4及5.本文对5个共晶化合物的晶体...     

The mass spectra of some phenyl pyridyl ketones

The mass spectra of phenyl 2-pyridyl, phenyl 3-methoxy-2-pyridyl, phenyl 4-methoxy-2-pyridyl, phenyl 5-methoxy-2-pyridyl, phenyl 6-methoxy-2-pyridyl ketones, phenyl 3-pyridyl and phenyl 6-methoxy-3-pyridyl ketones, and phenyl 4-pyridyl ketone were studied. The major fragmentation pathway of all the ketones results in the formation of[C₆H₅CO]⁺ and [C₅H₄NCO]⁺ type ions. Another fragmentation path is the loss of carbon monoxide with formation of an [M ? CO]⁺ ion after skeletal rearrangement.     

Synthesis of polyphenylene ether and thioether ketones

The known polymerization of 4,4′-difluorobenzophenone (DFB) with the dianion of hydroquinone to poly(phenylene ether ether ketone) (PEEK) and polymerization of either DFB with the dianion of 4,4′-dihydroxybenzophenone or self polycondensation of the anion of 4-hydroxy-4′-fluoro-benzophenone to poly(phenylene ether ketone) (PEK) were studied in N-cyclohexyl-2-pyrrolidone (CHP), which is a high-boiling aprotic polar solvent. The formation of high-molecular weight PEEK and PEK in this solvent was very efficient. The reactivity in CHP can be ascribed to effective solvation of metal ions rendering the anion very reactive toward nucleophilic substitution. The polymerization was extended to 4,4′-bis(4-fluorobenzoyl)diphenyl ether and 1,4-bis[4-(4-fluorobenzoyl)phenoxy]benzene to give a high molecular weight polymer with PEK and PEEK repeating units and PEEK respectively. The polymerization of DFB with purified anhydrous sodium sulfide in CHP gave rapidly a high molecular weight poly(phenylene ketone sulfide) (PKS). In contrast, diphenyl sulfone (DPS) was not very effective in obtaining such a high molecular weight PKS even with prolonged heating, which suggests the uniqueness of CHP in promoting a high degree of polymerization.     

Sulfur nitride in organic chemistry. 9. The reaction of tetrasulfur tetranitride with benzyl ketones. Preparation of 3,4-disubstituted-1,2,5-thiadiazoles

The reaction of tetrasulfur tetranitride ( 1 ) with various aryl and alkyl benzyl ketones ( 2a-o ), oxindole ( 11 ), benzyl α-pyridyl ketone ( 12 ) and α-phenacylpyridine ( 13 ) afforded the corresponding 1,2,5-thiadiazoles ( 3a-n, 11 and 14 ). The scope and limitations of the above reaction were investigated and the evidences suggesting the radical anion mechanism are presented.     

Cyanide attack at low-spin iron(II)–diimine complexes: the structure of a cyanide-containing derivative of a leaving ligand

The isolation and structural characterisation of the product of addition of HCN to the Schiff base derived from phenyl 2-pyridyl ketone and 3,4-dimethylaniline (Me2bsb) provides evidence in favour of a mechanism involving nucleophilic attack at the coordinated ligand for reaction of the complex [Fe(Me₂bsb)₃]²⁺ with cyanide.     

Generation of 1,2-ethanebis(trithiocarbonic acid) dianion from 2,2′-[1,2-ethanediylbis(thio)]- bis-1,3-dithiolane and its reaction with alkyl halides

Generation of 1,2-ethanbis(trithiocarbonic acid) dianion from 2,2′-[1,2-ethanediylbis (thio)]bis-1,3-dithiolane and its reaction with alkyl halldes were investigated.     

Electron impact mass spectra of 2-(2-pyridyl)methylene-1,3-dicarbonyl compounds: Unusual abundance of the [M + 1]+ ion and the effect of stereochemistry

Electron impact mass spectra of 2-(2-pyridyl)methylene-1,3-dicarbonyl compounds and related heteroaryl species have been investigated. In 3-(2-pyridyl)methylene-2,4-pentanedione, its 6′-methyl and 6′-methoxycarbonyl derivatives and in E- and Z-ethyl 3-oxo-2-(2-pyridyl)methylenebutanoates the base peak arises from the loss of methyl radical from the molecular ion to produce a 3-oxo-3H-indolizinium ion. A marked difference is observed in the behaviour of the geometric isomers of the keto esters. The diketones and E-keto ester carrying a 2-pyridyl substituent and ketone functionality on the same side of the carbon-carbon double bond exhibit an unusually high [M + 1]⁺/[M]^+˙ ratio (about 2.5) under normal ionization conditions (pressure 10–100 μPa). This abnormality is a function of pressure only and independent of temperature. In the case of the Z-keto ester, the corresponding malonate, 3- and 4-(2-pyridyl)methylene-2,4-pentanediones, and 2-furyl, 2-thienyl and phenyl diketone analogues, the ratio does not differ much from that due to the natural isotope abundance. Results for 1,1,1,5,5,5-hexadeuterio-2-(2-pyridyl)-methylene-2,4-pentanedione (strong M + 2 peak) suggest one mass unit transfer as an intermolecular proton shift from a methyl group to give a 3-hydroxy-3-methyl-3H-indolizinium ion. This real mass spectrometric phenomenon is a unique example of low pressure self-chemical ionization.     

Dianion of 1,2-bis(4′,4′-dimethyl-2′-oxazolin-2′-yl)ethane versatile synthetic reagent for annulation

Treatment of 1,2-bis(4′, 4′-dimethyl-2′-oxazolin-2′-yl)ethane with butyllithium produced the corresponding dianion, which on exposure with 1, ω -dihalides gives cyclic derivatives. The same dianion reacts with the β-bromoesters to yield substituted cyclopentanones.     

Reversible redox behavior between stannole dianion and bistannole-1,2-dianion

The reversible redox behavior between the stannole dianion and the bistannole-1,2-dianion is demonstrated. Reaction of the stannole dianion with oxygen (1 eq) gives the 1,2-bistannole-1,2-dianion which is a tin-analogue of the cyclopentadienyl anion in 94% yield. Reaction of the stannole dianion with ferrocenium tetrafluoroborate (1 eq) also gives the 1,2-dianion. The 1,2-bistannole-1,2-dianion has a nonaromatic nature as evidenced by X-ray and NMR analysis. Reduction of the 1,2-dianion with lithium gives the starting dianion.     

Synthesis of well-defined chain-end- and in-chain-functionalized polystyrenes with a definite number of benzyl chloride moieties and D-glucose residues

Novel well-defined chain-end- and in-chain-functionalized polystyrenes with six, eight, twelve, and sixteen benzyl chloride moieties and with four and eight D-glucose residues have been successfully synthesized by developing the methodology based on living anionic polymerization of using new functionalized agents derived from functionalized 1,1-diphenylethylene (DPE) derivatives. They are 1,10-dichloro-4,4-7,7-tetra(3-methoxymethylphenyl)decane, its iodide derivative, the dianion prepared from 1,1-bis(3-methoxymethylphenyl)ethylene and potassium naphthalenide, and 1,1-bis[3′,5′-bis(1,2:5,6-di-O-isopropylidene-α-D-glucofuranose-3-oxymethyl)phenyl]ethylene. The developed methodology involves diverse modes of reactions of polystyryllithium with new functionalized agents and either the subsequent transformation reaction with BCl₃ into benzyl chloride moieties or acid-hydrolysis to regenerate D-glucose residues. The resulting chain-multi-functionalized polystyrenes were precisely controlled with respect to chain length and quantitatively functionalized within experimental errors.     

Unusual Hydrogen-bonding Networks Consisting of π-Extended 4,4′-Bipyridines and Chloranilic Acid

Hydrogen-bonding networks of π-extended 4,4′-bipyridines, 2,5-di(4-pyridyl)thiophene (1), 2,5-di(4-pyridyl)furan (2) and 1,4-di(4-pyridyl)benzene (3) with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, CA) have been investigated. The dipyridyl compounds afforded complexes 4 [(dication of 1)·(monoanion of CA)²], 5 [(dication of 2)·(dianion of CA)·(MeOH)] and 6 [(3)·(dication of 3)·(dianion of CA)·(H²O)⁶] with CA. X-ray structure analyses revealed the formation of unusual molecular tape and sheet structures involving N–H ?O, O–H ?O, C–H ?O and N–H ?N hydrogen bonds, where the aromatic spacer groups play an important role in constructing the unique crystal structures.     

Halogen versus Hydrogen Bonding in Binary Cocrystals: Novel Conformation a Coformer with [2+2] Photoreactivity of Criss-Crossed C=C Bonds

A series of cocrystals involving the hydrogen- and halogen-bond donor coformers catechol ( cat ) and 1,2-diiodotetrafluorobenzene ( 1,2-di-I-tFb ), respectively, is reported. Each coformer forms a cocrystal with each of the three symmetric bipyridines trans-1,2-bis(n-pyridyl)ethylene ( n , n′ -bpe , where: n=n′=2, 3, 4). Four novel cocrystals ( cat ) ⋅ ( 3,3′-bpe ), 2( 1,2-di-I-tFb ) ⋅ ( 2,2′-bpe ), 2( 1,2-di-I-tFb ) ⋅ ( 3,3′-bpe ), and ( 1,2-di-I-tFb ) ⋅ ( 4,4′-bpe ) comprise components that assemble by either O−H⋅⋅⋅N hydrogen bonds ( cat ) or N⋅⋅⋅I halogen bonds ( 1,2-di-I-tFb ). In ( cat ) ⋅ ( 3,3′-bpe ), cat acts as a template to support an intermolecular [2+2] photocycloaddition of 3,3′-bpe . The reactivity occurs via a one-dimensional (1D) hydrogen-bonded tape with stacked and criss-crossed olefins that react stereoselectively and quantitatively to form rctt-tetrakis(3-pyridyl)cyclobutane ( 3,3′-tpcb ). The reactivity of the criss-crossed olefins is facilitated by a hitherto not reported cis-gauche conformation adopted by cat . The stereochemistry of 3,3′-tpcb is confirmed in the cocrystal 2( cat ) ⋅ ( 3,3′-tpcb ).     

Ionic-liquid-promoted decaborane olefin-hydroboration: a new efficient route to 6-R-B10H13 derivatives

Unlike in conventional organic solvents where transition metal catalysts are required, decaborane olefin-hydroboration reactions have been found to proceed in biphasic ionic-liquid/toluene mixtures with a wide variety of olefins, including alkyl, alkenyl, halo, phenyl, ether, ester, pinacolborane, ketone, and alcohol-substituted olefins, and these reactions now provide simple high-yield routes to 6-R-B10H13 derivatives. Best results were observed for reactions with bmimX (1-butyl-3-methylimidazolium, X = Cl(-) or BF4(-)) and bmpyX (1-butyl-4-methylpyridinium, X = Cl(-) or BF4(-)). Both the experimental data for these reactions and separate studies of the reactions of B10H13(-) salts with olefins indicate a reaction sequence involving (1) the ionic-liquid-promoted formation of the B10H13(-) anion as the essential initial step, (2) the addition of the B10H13(-) anion to the olefin to form a 6-R-B10H12(-) anion, and finally, (3) protonation of 6-R-B10H12(-) to form the final neutral 6-R-B10H13 product. The 6-R-B10H13 derivatives also undergo ionic-liquid-mediated dehydrogenative alkyne-insertion reactions in biphasic bmimCl/toluene mixtures, and these reactions provide high yield routes to 3-R-1,2-R' 2-1,2-C2B10H9 ortho-carborane derivatives.     

Molybdenum carbonyl complexes of binucleating pyridine-based ligands

Reaction of [Mo(CO)₄(diene)] with 4,4′-bipyridine (44′B), trans-1,2-bis(2-pyridyl)ethene (2-bpe) and trans-1,2-bis(4-pyridyl)-ethene (4-bpe) gives polymeric [Mo(CO)₄(44′B)]_n, mononuclear cis-[Mo(CO)₄(2-bpe)₂] and binuclear [Mo(CO)₄(4-bpe)]₂ respectively. Reaction of the same ligands with [Mo(CO)₄(bpy)] (bpy is 2,2′-bipyridine) produces the bridged binuclear complexes [{Mo(CO)₃(bpy)}₂(44′B)] and [{Mo(CO)₃(bpy)}₂(4-bpe)]. Products are characterised by microanalysis and spectroscopy (IR, ¹H NMR, UV/vis). Reduction of [{Mo(CO)₃(bpy)}₂(44′B)] produces an anion in which the unpaired electron is localised on the chelating bpy ligand.     

The autoxidation of 2-(2-aminophenyl)-3- methylindole

Fischer indolisation of 2-aminophenyl ethyl ketone phenylhydrazone using glacial acetic acid saturated with hydrogen chloride as catalyst affords 3-methylindolo(l′:2′-3:4)2-methylquinazoline and 2-(2-aminophenyl)-3-methylindole. The latter compound is autoxidised to 2-(2-amino-phenyl)-3-hydroxy-3-methyl-3H-indole, a reaction which is shown to be dependent upon the presence of the primary amino group at the 2-position of the 2-phenyl substituent and which is much slower than the corresponding autoxidation of 2-(2-hydroxyphenyl)-3-methylindole to 3-hydroxy-2-(2-hydroxyphenyl)-3-methyl-3H-indole previously reported.Nitration of isopropyl phenyl ketone occurs preferentially at the ortho- rather than the meta- positions of the benzene nucleus.     

Chlorodiazaphospholines as intermediates in the synthesis of 1,2-dihydro-2-alkenyl-3H-pyrazol-3-ones and 2-pyrrolylacetates

New derivatives of 1,2-dihydro-2-alkenyl-3H-pyrazol-3-ones 6 and 7 have been synthesized at room temperature by a one-pot two-step reaction of PCl₃, a ketone methylhydrazone, and a β -keto ester. With ketone methylhydrazones bearing at least a phenyl group in the α -positions to the CN bond and in the second step β -keto esters, such as propionyl- or butyrylacetates, we obtained 2-pyrrolylacetates 8 as unexpected products together with pyrazolones 7 . The ratio of the two products depends on the nature of the groups in the α -positon to the CN bond. A chlorodiazaphospholine 1 is the key intermediate of this new reaction, and a plausible mechanism of formation of the azaheterocycles is reported.     

Syntheses of 1,3-disubstituted imidazo[l,5-a]pyridines

Facile syntheses of 1,3-disubstituted imidazo[l,5-a]pyridines have been effected by treatment of ketimines derived from di-2-pyridyl ketone with LDA and benzophenone, reactions of benzyl amine with di-2-pyridyl ketone in boron trifluoride etherate, and reaction of di-2-pyridyl methanamine imines with molecular sieves in benzene.     

Formal Umpolung Addition of Phosphites to 2-Azaaryl Ketones under Chiral Brønsted Base Catalysis: Enantioselective Protonation Utilizing [1,2]-Phospha-Brook Rearrangement

The formal enantioselective umpolung addition of dialkyl phosphites to 2-azaaryl ketones was developed under Brønsted base catalysis. The reaction involves the enantioselective protonation of the transient α-oxygenated (2-azaaryl)methyl anion generated through the 1,2-addition of the anion of dialkyl phosphite to the 2-azaaryl ketone and the subsequent [1,2]-phospha-Brook rearrangement. A chiral bis(guanidino)iminophosphorane organosuperbase efficiently catalyzed the reaction to provide enantio-enriched phosphates in high yields with good to high enantioselectivities. This is a rare example of the catalytic enantioselective protonation of transient carbanions other than enolates, constructing a trisubstituted stereogenic center α to 2-azaarenes.