Synthesis of polymer intermediates containing the hexafluoroisopropylidene group via functionalization of 2,2-diphenylhexafluoropropane

The title compound was synthesized by hydrogenolysis of its precursor 2,2-bis(4-trifluoromethanesulfonatophenyl)hexafluoropropane ( 2 ) in the presence of a base. 2,2-Diphenylhexafluoropropane ( 6 ) can be appropriately functionalized at the 3,3′-positions to give the diamino ( 7 ), dibromo ( 11 ), dicarboxaldehydo ( 13 ), 3-ethynyl-3′-carboxaldehydo ( 14 ) derivatives which are important monomers in the synthesis of various high-temperatures resistant polymers and oligomers containing the hexafluoroisopropylidene (6F) group. 2,2-Bis(4-triflatophenyl)hexafluoropropane ( 2 ) undergoes quantitative dinitration at the 3,3′-positions to yield 2,2-bis(3-nitro-4-triflatophenyl)hexafluoropropane ( 3 ) which ultimately leads to the 3,3′-diamino-4,4′-bis(arylamino) ( 5 ) and 3,3′-diamino-4,4′-dihydroxy ( 8 ) derivatives which are specifically designed for phenylbenzimidazole, benzimidazoquinazoline, and benzoxazole polymers and oligomers.     

Stereoinvertive C–C Bond Formation at the Boron-Bound Stereogenic Centers through Copper-Bipyridine-Catalyzed Intramolecular Coupling of α-Aminobenzylboronic Esters

Enantiospecific intramolecular Suzuki–Miyaura-type coupling with α-(2-halobenzoylamino)benzylboronic esters to give 3-substituted isoindolinones is achieved by using copper catalysts with 2,2′-bipyridine-based achiral ligands. Enantioenriched α-aminobenzylboron reactants bearing a hydrogen atom at the boron-bound stereogenic carbons undergo stereoinvertive coupling in the presence of a 6-phenyl-2,2′-bipyridine ligand with high enantiospecificity. α-Aminobenzylboronates bearing fully substituted boron-bound stereogenic centers also gave the 3,3-disubstituted isoindolinones with stereospecific stereochemical inversion in the presence of simple 2,2′-bipyridine as a ligand.     

A convenient ring formation of 3-aryl-2,2-dialkyl-2,3-dihydrobenzofurans from phenols and 2-aryl-2,2-dialkylacetaldehydes

A new and simple route for the preparation of 3-aryl-2,2-dialkyl-2,3-dihydrobenzofurans from phenols is described. In the presence of an acid catalyst phenols react with 2-aryl-2,2-dialkylacetaldehydes, prepared in good yield from 2-arylacetonitriles in 2 steps, to give 3-aryl-2,2-dialkyl-2,3-dihydrobenzofurans. Electron-donating substituents were required on the phenols in order to give 3-aryl-2,2-dialkyl-2,3-dihydrobenzofurans in good yield.     

Platinum complex-catalyzed hydrosilylation and isomerization of methylenecyclopropane derivatives. Effect of structures of the substrate and catalyst

PtI(2)(PPh(3))(2) catalyzes hydrosilylation of 2,2-diphenyl-1-methylenecyclopropane with HSiEt(3), HSiPh(3), HSiEt(2)Ph, HSiPhCl(2), and HSiCl(3) under solvent-free conditions at 140 degrees C to produce the silyl compounds with a (2,2-diphenylcyclopropyl)methyl substituent in moderate to high yields without ring-opening of the substrate. PtI(2)(PPh(3))(2) is converted by the reaction into PtH(I)(PPh(3))(2), which also catalyzes the hydrosilylation of the methylenecyclopropanes. The reaction of 2-phenyl-1-methylenecyclopropane, 2-methyl-2-phenyl-1-methylenecyclopropane, 2,2-diphenethyl-1-methylenecyclopropane, and alkylidenecyclopropanes with HSiEt(3) catalyzed by PtI(2)(PPh(3))(2) causes addition of hydrosilane to the substrate accompanied by ring-opening. 2,2-Diphenyl-1-methylenecyclopropane undergoes ring-opening isomerization in the presence of HSi(OEt)Me(2) and Pt(PEt(3))(3) catalyst to give 1,1-diphenyl-1,3-butadiene. The pathways for the hydrosilylation and the isomerization are discussed.     

Palladium-Catalyzed Syntheses of Polyethynyl-Substituted 2,2′-Bithiophenes

The syntheses of polyethynyl-substituted 2,2′-bithiophenes 2 and related 5,5′-dicarbaldehyde derivatives 1 are described. The treatment of easily available polybrominated 2,2′-bithiophenes 3 and 2,2′-bithiophene-5,5′-dicarbaldehydes 4 with phenyl or (trimethylsilyl)acetylene in the presence of Pd^II and Cu^I in (i-Pr)₂NH yields substituted polyethynyl-2,2′-bithiophene compounds. The Me₃Si protecting groups can be removed by protodesilylation under basic conditions to give the corresponding terminal ethynyl groups. These polyethynyl-bithiophenes could be interesting precursors for the synthesis of macrocycles with interesting properties.     

Syntheses of 4-(2-hydroperoxy-2,2-diarylethyl)-3,5-dimethylpyrazoles, 4-(2-hydroxy-2,2-diarylethyl)-3,5-dimethylpyrazoles and the related compounds

The reactions of 1,1-disubstituted ethenes with 2,4-pentanedione in the presence of manganese(III) acetate and atmospheric oxygen yielded 4-acetyl-6,6-diaryl-3-methyl-1,2-dioxan-3-ols. The latter gave 4-(2-hydroperoxy-2,2-diarylemyl)-3,5-dimethylpyrazoles by the reaction with hydrazines in methanol-acetic acid (1:1 v/v) at 50° in 15-77% yields, or 4-(2-hydroxy-2,2-diarylethyl)-3,5-dimethylpyrazoles by the reaction with hydrazines in methanol in 2-78% yields. The acid-catalyzed reaction of 4-(2-hydroperoxy-2,2-diarylethyl)-3,5-dimethylpyrazoles yielded 4-(aroylmethyl)-3,5-dimethylpyrazoles (15-55%) and 4-(2,2-diarylethenyl)-3,5-dimethylpyrazoles (9-29%).     

Spectrophotometric determination of ethanol by an enzymatic method with 2, 2'-azino-di(3-ethylbenzthiazo- line-6-sulfonate)

The method is based on the oxidation of ethanol in the presence of alcohol oxidase, followed by oxidation of 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonate) in the presence of peroxidase.     

Aldol condensation of 6-alkoxy-2,2-dimethylchroman-4-ones with substituted benzaldehydes using tetramethylorthosilicate and potassium fluoride

The aldol condensation of 6-alkoxy-2,2-dimethylchromanones 1 or 2 with substituted benzaldehydes in the presence of tetramethylorthosilicate and potassium fluoride affords 6-alkoxy-3-benzylidene-2,2-dimethylchromanones 5-10 while other conventional methods were unsuccessful.     

Preparation and Characterization of Antimony and Arsenic Tricyanide and Their 2,2′‐Bipyridine Adducts

The arsenic(III) and antimony(III) cyanides M(CN)₃ (M=As, Sb) have been prepared in quantitative yields from the corresponding trifluorides through fluoride–cyanide exchange with Me₃SiCN in acetonitrile. When the reaction was carried out in the presence of one equivalent of 2,2′‐bipyridine, the adducts [M(CN)₃ ? (2,2′‐bipy)] were obtained. The crystal structures of As(CN)₃, [As(CN)₃ ? (2,2′‐bipy)] and [Sb(CN)₃ ? (2,2′‐bipy)] were determined and are surprisingly different. As(CN)₃ possesses a polymeric three‐dimensional structure, [As(CN)₃ ? (2,2′‐bipy)] exhibits a two‐dimensional sheet structure, and [Sb(CN)₃ ? (2,2′‐bipy)] has a chain structure, and none of the structures resembles those found for the corresponding arsenic and antimony triazides.     

Synthesis and structural studies of homooligomers of geminally disubstituted β(2,2)-amino acids with carbohydrate side chain

A new class of geminally disubstituted C-linked carbo-β(2,2)-amino acids (β(2,2)-Caa) were prepared from d-glucose. The structures of homooligomeric di-, tetra-, and hexapeptides prepared from (S)-β(2,2)-Caa were studied with NMR (in CDCl(3)), CD, and Molecular Dynamics calculations. These β(2,2)-peptides have shown the presence of stable 6-membered (6-mr) NH(i)···CO(i) intra-residue H-bonded (C(6)) strands. It was found that the strand structures realized in these systems were additionally stabilized by the electrostatic interaction arising due to the proximity of amide proton (NH(i)) to the oxygen of the preceding methoxy group (O(Me)(i-1)) at the C3 carbon of the carbohydrate ring. The new β(2,2)-Caa residues with additional support to H-bonding considerably expand the domain of foldamers.     

Efficient Isomerization for Preparing thans-2,2-Dimethyl-3-(2,2-dichloroethenyl) cyclopropanecarbonyl Chloride

2,2-Dimethyl-3-(2,2-dichloroethecyclopropanecarbonylchloride(hereafterreferredtoaspermethricacidchloride)isausefulintermediateforthepreparationofsomesyntheticpyrethroids,suchaspermethrinandcypermethrin.Permethricacidchloridehasageometricalisomericpair,oiLyandtrans,owingtoitscyclopropanering.Itisknownthat,ingeneral,theestersderivedfromtheirans-isomerarelesstoxictomammalsthanthosederivedfromtheets-isomerl--3.Thepermethricacidproducedindustriallyisalwaysinformsofmixturesoftrans-andets-isomers.Ac…     

Stereoinvertive C–C Bond Formation at the Boron‐Bound Stereogenic Centers through Copper‐Bipyridine‐Catalyzed Intramolecular Coupling of α‐Aminobenzylboronic Esters

Enantiospecific intramolecular Suzuki–Miyaura‐type coupling with α‐(2‐halobenzoylamino)benzylboronic esters to give 3‐substituted isoindolinones is achieved by using copper catalysts with 2,2′‐bipyridine‐based achiral ligands. Enantioenriched α‐aminobenzylboron reactants bearing a hydrogen atom at the boron‐bound stereogenic carbons undergo stereoinvertive coupling in the presence of a 6‐phenyl‐2,2′‐bipyridine ligand with high enantiospecificity. α‐Aminobenzylboronates bearing fully substituted boron‐bound stereogenic centers also gave the 3,3‐disubstituted isoindolinones with stereospecific stereochemical inversion in the presence of simple 2,2′‐bipyridine as a ligand.     

Asymmetric desymmetrization of 2,2',6,6'-tetrahydroxybiphenyl through annulation with enantiomerically pure bis(mesylate)

[formula: see text] 2,2',6,6'-Tetrahydroxybiphenyl undergoes a facile annulation reaction with bis(mesylate) derived from (S)-1,2-propanediol in the presence of Cs2CO3 to give the corresponding asymmetric desymmetrization product of S axial chirality with exclusive diastereoselectivity. The desymmetrization product can be utilized as a versatile chiral building block in asymmetric synthesis of axially chiral 6,6'-disubstituted 2,2'-biphenyldiols.     

Energetic and conformational changes upon complexation of gelatin with sodium dodecyl sulfate

The effect of sodium bis(2-ethylhexyl)sulfosuccinate/isooctane/water microemulsions on the stability of 2,2-dimethyl-2,3-dihydro-1-benzofuran-7-yl methylcarbamate (carbofuran, CF), 3-hydroxy-2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate (3-hydroxycarbofuran, HCF) and 3-keto-2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate (3-ketocarbofuran, KCF) in basic media has been studied. The presence of these microheterogeneous media implies a large basic hydrolysis of CF and HCF on increasing surfactant concentration and, also, on increasing water content in the microemulsion. The hydrolysis rate constants are approximately 2- and 10-fold higher than those in pure water for HCF and CF, respectively. In contrast, a steep descent in the rate of decomposition for KCF was observed. These behaviours can be ascribed to the presence of CF derivatives both in the hydrophilic phase and in the lipophilic phase, while the hydroxyl ions are only restricted to the water pool of the microemulsion (hydrophilic phase). The kinetic rate constants for the basic hydrolysis in AOT-based microemulsions have been obtained on the basis of a pseudophase model. Taking into account that an important part of soils are colloids, the possibility of the presence of restricted water environments implies that soil composition and its structure will play an important role in the stability of these carbamates. In fact, we observed that the presence of these restricted aqueous media in the environment, in particular in watersheds and in wastewaters, could reduce significantly the half-life of these pesticides (33% and 91% for HCF and CF, respectively).     

Novel synthesis of 2,2-dialkyl-3-dialkylamino-2,3-dihydro-1H-naphtho[2,1-b]pyrans

2,2-Dialkyl-3-dialkylamino-2,3-dihydro-1H-naphtho[2,1-b]pyrans were prepared from 2-naphthol, a secondary amine, and 3-hydroxy-2,2-dialkylpropanal in the presence of a catalytic amount of p-toluenesulfonic acid. This one-pot reaction involves retro-aldol disintegration of 3-hydroxy-2,2-dialkylpropanal followed by formation of a Mannich base intermediate from 2-naphthol, a secondary amine, and formaldehyde (retro-aldol product). This Mannich base then disproportionates into a quinone methide intermediate and the secondary amine is regenerated. It then forms an enamine intermediate with 2,2-dialkylacetaldehyde (another retro-aldol product). Finally, the quinone methide intermediate undergoes electrocyclic ring closure with enamines to produce the title compounds.     

Synthesis of 6-carboxy-2,2-dimethylchromans and chromenes

The condensation of hydroxybenzoic acids and their methyl esters with isoprene in the presence of orthophosphoric acid gives corresponding 2,2-dimethylchromans, which can be dehydrogenated with DDQ or NBS to give the corresponding 6-carboxy-2,2-dimethylchromenes. The synthesis of β-tubaic acid, a natural compound, has also been achieved.     

Photochemische Cycloadditionen von 3-Phenyl-2H-azirinen mit kumulierten Doppelbindungen. Vorläufige Mitteilung

Irradiation of 2-methyl- ( 1c ) and 2,2-dimethyl-3-phenyl-2H-azirine ( 1d ) in benzene solution in the presence of carbon dioxide yields 2-methyl-4-phenyl- ( 3c ) and 2,2-dimethyl-4-phenyl-3-oxazolin-5-one ( 3d ), respectively. Similar cycloadducts are observed (see table) when 2,3-diphenyl-2H-azirine ( 1b ) and 1d are irradiated in the presence of phenylisocyanate, o-tolylisocyanate, phenylisothiocyanate or di-o-tolyl-carbodiimide.     

Synthesis, structure, magnetism and nuclease activity of tetranuclear copper(II) phosphonates containing ancillary 2,2'-bipyridine or 1,10-phenanthroline ligands

The reaction of cyclohexylphosphonic acid (C(6)H(11)PO(3)H(2)), anhydrous CuCl(2) and 2,2'-bipyridine (bpy) in the presence of triethylamine followed by a metathesis reaction with KNO(3) afforded [Cu(4)(mu-Cl)(2)(mu(3)-C(6)H(11)PO(3))(2)(bpy)(4)](NO(3))(2) (1). In an analogous reaction involving Cu(OAc)(2).H(2)O, the complex [Cu(4)(mu-CH(3)COO)(2)(mu(3)-C(6)H(11)PO(3))(2)(2,2'-bpy)(4)](CH(3)COO)(2) (2) has been isolated. The three-component reaction involving Cu(NO(3))(2).3H(2)O, cyclohexylphosphonic acid and 2,2'-bipyridine in the presence of triethylamine afforded the tetranuclear assembly [Cu(4)(mu-OH)(mu(3)-C(6)H(11)PO(3))(2)(2,2'-bpy)(4) (H(2)O)(2)](NO(3))(3) (3). Replacing 2,2'-bipyridine with 1,10-phenanthroline (phen) in the above reaction resulted in [Cu(4)(mu-OH)(mu(3)-C(6)H(11)PO(3))(2)(phen)(4)(H(2)O)(2)](NO(3))(3) (4). In all the copper(II) phosphonates (1-4) the two phosphonate ions bridge the four copper(II) ions in a capping coordination action. Each phosphonate ion bridges four copper(II) ions in a mu(4), eta(3) coordination mode or 4.211 of the Harris notation. Variable-temperature magnetic studies on reveal that all four complexes exhibit moderately strong intramolecular antiferromagnetic coupling. The DNA cleavage activity of complexes 1-4 is also described. Compounds 1 and 3 were able to completely convert the supercoiled pBR322 DNA form I to nick form II without any co-oxidant. In contrast, 50% conversion occurred with and 40% with 4. In the presence of magnesium monoperoxyphthalate all four compounds achieved rapid conversion of form I to form II.     

Improved Synthesis of 1‐Hydroxy‐2,2,5,5‐tetramethyl‐3‐imidazoline 3‐Oxide (HTIO)

A simple, efficient, mild, and reproducible method for the synthesis of 1‐hydroxy‐2,2,5,5‐tetramethyl‐3‐imidazoline 3‐oxide is described. The method is based on the condensation of 2‐hydroxyamino‐2‐methylpropanal oxime with 2,2‐diethoxypropane in the presence of an equimolar quantity of acetic acid. Cost‐effectiveness of the condensation procedure could be also achieved by replacing 2,2‐diethoxypropane with less expensive 2,2‐dimethoxypropane.     

Effect of reaction conditions on the hydration of isoprene

Effect of conditions (partial pressure of isoprene, temperature, catalyst concentration, medium) on the rate and selectivity of reactions occurring in interaction of isoprene with water in the presence of orthophosphoric acid as a catalyst was studied at elevated temperatures and pressures in the liquid phase. The reaction orders with respect to isoprene were determined for reactions in which 3-methylbutanone-2,2-methylbutanal, and 2,2-dimethylpropanal are formed. The applicability of various acidity characteristics for describing the rates of the reactions under study are considered.