Poly(N-bromobenzene-1,3-disulfonamide) and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide as novel catalytic reagents for silylation of alcohols, phenols, and thiols using hexamethyldisilazane

Poly(N-bromobenzene-1,3-disulfonamide) [PBBS] and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide [TBBDA] are effective catalysts for the silylation of alcohols, phenols, and thiols in the presence of hexamethyldisilazane with, or without solvent, and also under microwave irradiation.     

Poly(N-bromo-N-ethylbenzene-1,3-disulfonamide) and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide as efficient reagents for synthesis of quinolines

Poly(N-bromo-N-ethylbenzene-1,3-disulfonamide) [PBBS] and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide [TBBDA] were used as efficient reagents for the synthesis of quinolines in excellent yields from 2-aminoaryl ketones and carbonyl compounds under aqueous and solvent-free conditions.     

Poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide), N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide and novel poly(N,N′-dibromo-N-phenylbenzene-1,3-disulfonamide) as powerful reagents for benzylic bromination

N,N,N′,N′-Tetrabromobenzene-1,3-disulfonamide [TBBDA], poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide) [PBBS], and novel poly(N,N′-dibromo-N-phenylbenzene-1,3-disulfonamide) [PBPS] can be used for bromination of benzylic positions in solvent.     

Highly efficient one-pot synthesis of tetrahydropyridines

The combination of aromatic aldehydes, and 1,3-dicarbonyl compounds in the presence of a catalytic amount of poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide) [PBBS] and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide [TBBDA] leads to the formation of highly substituted tetrahydropyridines. In this way, a series of pharmacologically interesting substituted piperidine derivatives were obtained in moderate to high yields at room temperature.     

One-pot synthesis of 2-amino-3-cyanopyridine derivatives under solvent-free conditions

A series of 2-amino-3-cyanopyridines were obtained from aryl aldehydes, substituted acetophenones, malononitrile and ammonium acetate in good to excellent yields by proceeding through a simple, mild and efficient procedure utilizing N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide [TBBDA] and poly(N-bromo-N-ethylbenzene-1,3-disulfonamide) [PBBS] as catalysts.     

Interaction of 3,5-di-tert-butyl-o-benzoquinone with secondary amines—a pathway to new sterically hindered N,N-disubstituted o-aminophenols

The interaction of 3,5-di-tert-butyl-o-benzoquinone with secondary amines has been studied. The synthetic procedure was developed in order to synthesize a series of new N,N-disubstituted o-aminophenols. The interaction of 3,5-di-tert-butyl-o-benzoquinone with dimethylamine leads to 2-(N,N-dimethylamino)-4,6-di-tert-butyl-phenol, which is oxidized in the reaction medium by the parent 3,5-di-tert-butyl-o-benzoquinone forming spirocompound 4,5′,6,7′-tetra-tert-butyl-3′-methyl-3′H-spiro[1,3-benzodioxol-2,2′-[1,3]benzoxazole].     

N,N,N,N-Tetramethyl-1,3-propanediamine as the catalyst of choice for the Baylis-Hillman reaction of cycloalkenone: rate acceleration by stabilizing the zwitterionic intermediate via the ion-dipole interaction

N,N,N^′,N^′-Tetramethyl-1,3-propanediamine (TMPDA) can be used as an efficient catalyst for the Baylis-Hillman reaction of cycloalkenones. The increased reaction rate was thought be derived from the stabilizing effect of the zwitterionic intermediate via the ion-dipole interaction.     

An efficient,rapid and facile procedure for conversion of aldoximes to nitriles using triphenylphosphine and N-halo sulfonamides

N,N,N＇,N＇-Tetrabromobenzene-1,3-disulfonamide （TBBDA）/triphenylphosphine and N,N,N＇,N＇-tetra- chlorobenzene-1,3-disulfonamide （TCBDA）/triphenylphosphine have been introduced as highly efficient systems for the versatile conversion of aldoxime derivatives into nitriles. The process reported here is operationally simple and reactions have been mildly performed in dichloromethane at room temperature.     

Mild bromination of unreactive aromatic compounds

N,N,N′,N′-Tetrabromobenzene-1,3-disulfonamide and poly(N,N′-dibromo-N-ethylene-benzene-1,3-disulfonamide) in concentrated H₂SO₄ can be used as efficient reagents for the mild bromination of unreactive arenes at room temperature, under solvent-free conditions, in good yields.     

1,n-Diamines. Part 3: Microwave-assisted synthesis of N-acyl-N′-arylhexahydropyrimidines and hexahydro-1,3-diazepines

In this Letter we present a method for the synthesis of N-acyl-N′-arylhexahydropyrimidines 1, by ring closure of N-acyl-N′-aryl-1,3-propanediamines 3 with formaldehyde. Cyclodehydrations were performed in aqueous medium under microwave irradiation, and led to high yields of the desired compounds in remarkably short reaction times. The method also allowed for the synthesis of hitherto unreported N-acyl-N′-arylhexahydro-1,3-diazepines 2. The acyclic tetramethylenic precursors 4 were synthesized by selective functionalization of N-arylputrescines.     

DFT study of the reaction sites of N,N′-substituted p-phenylenediamine antioxidants

The geometry of N,N′-diphenyl-p-phenylenediamine (DPPD), N-phenyl-N′-(1′-methylbenzyl)-p-phenylenediamine (SPPD), N-phenyl-N′-(1,3-dimethyl-butyl)-p-phenylenediamine (6PPD), N-phenyl-N′-isopropyl-p-phenylenediamine (IPPD), and N-(1-methyl-1-phenylethyl)-N′-phenyl-p-phenylenediamine (CPPD) as well as of their dehydrogenation products has been optimized at B3LYP/6-31G^∗ level of theory. Our results support the idea of formation of stable ketimine Ph-NC structures (instead of quinonediimine structures) during consecutive dehydrogenation of SPPD, 6PPD, and IPPD antioxidants despite the formation of tertiary carbon-centered radicals in the first dehydrogenation step is energetically preferred for SPPD only.     

Copper(I) catalysis: Synthesis of N,N′-diarylated and N-aryl,N′-formylated chiral C2-symmetric diamines

Chiral N,N′-diaryl C₂-symmetric diamines and N-aryl,N′-formyl-trans-(1R,2R)-diaminocyclohexane are readily accessed by copper catalyzed N,N′-diarylation and N-aryl,N′-formylation of trans-(1R,2R)-diaminocyclohexane with aryl bromides. N,N′-diarylation using (R)-1,1′-binaphthyl-2,2′-diamine and iodobenzene gave the corresponding (R)-N,N′-diphenyl-1,1′-binaphthyl-2,2′-diamine derivative in 83% yield.     

Acyclic tertiary diamines and 1,4,7,10-tetraazacyclododecane with fluorine-containing β-diketones: Leading to low melting ionic adducts

N,N,N′,N′-Tetramethylmethanediamine (1a), N,N,N′,N′-tetramethylethanediamine (1b), N,N,N′,N′-tetramethyl-1,3-propanediamine (1c), and N,N,N′,N′-tetramethyl-1,6-hexanediamine (1d) were reacted at 25 °C with 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (2a), 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (2b), 2-thenoyltrifluoroacetone (2c), and 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione (2d) to form the ionic adducts 3-18. 1,4,7,10-Tetraazacyclododecane (1e) reacted at 25 °C with β-diketones (2a-d) and 1,1,1-trifluoro-2,4-pentanedione (2e) to give ionic solids 19-23 in good yields. Some of the products are liquid at 25 °C and are thermally stable over long liquid ranges as determined by thermal gravimetric analyses. Single-crystal X-ray structure determinations show that compounds 9 and 21 crystallize in the monoclinic space groups P2(1)/c and P2(1)/n, respectively. All the new compounds were characterized by ¹H, ¹⁹F and ¹³C NMR, electrospray MS and/or elemental analyses.     

Helicity of N,N′-diaryl-trans-1,2-diaminocyclohexane derivatives. Implications for molecular helicity manipulations

Derivatives of trans-1,2-diaminocyclohexane (DACH), useful as chiral ligands, scaffolds and building blocks, differ in their conformation. The conformation of N,N′-diaryl-DACH derivatives was studied by the semiempirical and DFT computational methods and by exciton-coupled circular dichroism. It was found that, contrary to M-helical N,N′-diimine, N,N′-diimide and N,N′-diamide derivatives, the aromatic residues in N,N′-diphenyl derivatives are oriented to form a P-helix for the (R,R)-DACH absolute configuration. The helicity of the bis-aryl system is modified in the case of 1-naphthyl or 2-naphthyl derivatives. Further switching of helicity has been demonstrated by either protonation or mono-N-acetylation of N,N′-diaryl DACH derivatives.     

One-pot synthesis of pyrimidines under solvent-free conditions

N,N,N’,N’-Tetrabromobenzene-1,3-disulfonamide was used as an efficient catalyst for the one-pot synthesis of pyrimidine derivatives in excellent yields from triethoxymethane, ammonium acetate, and various ketone derivatives at 100–110 °C under solvent-free conditions.     

Poly(N,N′-dichloro-N-ethyl-benzene-1,3-disulfonamide, N,N,N′,N′-tetrachlorobenzene-1,3-disulfonamide, poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide, and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide catalyzed formylation of amines and alcohols using ethyl formate under microwave irradiation

A simple, rapid, and efficient procedure for formylation of primary and secondary amines and alcohols using ethyl formate catalyzed with poly(N,N′-dichloro-N-ethyl-benzene-1,3-disulfonamide (PCBS), N,N,N′,N′-tetrachlorobenzene-1,3-disulfonamide (TCBDA), poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide (PBBS) and also N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide (TBBDA) was adopted. The reactions were performed under microwave irradiation with high yields.     

Unexpected course of rearrangement of substituted S-(1(3H)-isobenzofuranone-3-yl)isothiuronium bromides

Three series of S-(1(3H)-isobenzofuranone-3-yl)isothiuronium bromides differing in substitution at the isothiuronium moiety (none, one or two methyl groups) and at the benzene ring were prepared and characterized. These salts were then treated with various bases (acetate, triethylamine, Na₂CO₃) to give either 1-hydroxy-3-oxo-1,3-dihydro-2H-isoindol-2-carbothioamides or the product of S to N isobenzofuranone-3-yl migration, i.e., 1,3-dimethyl-1-(3-oxo-1,3-dihydro-2-benzofuran-1-yl)thioureas. If ammonia was used in reaction with N,N′-dimethyl isothiuronium salts then 3-hydroxy-2,3-dihydro-1H-isoindol-1-ones were formed together with 1,3-dimethyl-1-(3-oxo-1,3-dihydro-2-benzofuran-1-yl)thioureas in parallel reaction with the yields increasing with ammonia concentration. The formation of isoindolones takes place in two steps with an aldehyde intermediate, which can be trapped with N,N-dimethylhydrazine.     

Cascade assembly of N,N′-dialkylbarbituric acids and aldehydes: a simple and efficient one-pot approach to the substituted 1,5-dihydro-2H,2′H-spiro(furo[2,3-d]pyrimidine-6,5′-pyrimidine)-2,2′,4,4′,6′(1′H,3H,3′H)-pentone framework

Cascade assembly of N,N′-dialkylbarbituric acids and aldehydes in the presence of bromine leads to the selective and efficient formation of substituted 1,5-dihydro-2H,2′H-spiro(furo[2,3-d]pyrimidine-6,5′-pyrimidine)-2,2′,4,4′,6′-(1′H,3H,3′H)-pentones in 70-88% yields via a complex cascade process. Spirobarbiturates containing the furo[2,3-d]pyrimidine framework are a class of compounds with interesting pharmacological and physiological activity.     

Synthesis of N,N′-bis and N,N,N′,N′-tetra-[(3,5-di-substituted-1-pyrazolyl)methyl]para-phenylenediamines: new candidate ligands for metal complex wires

A series of tridentate ligands N,N-bis-[(di-substituted-1-pyrazolyl)methyl]arylamines 2-3a,b and benzylamine 4a,b, tetradentate N,N′-bis-[(di-substituted-1-pyrazolyl)methyl]para-phenylenediamines 7a,b and hexadentate N,N,N′,N′-tetra-[(di-substituted-1-pyrazolyl)methyl]para-phenylenediamines 8a,b has been prepared in good yield by condensation of arylamines, benzylamine or para-phenylenediamine with N-hydroxymethyl disubstituted pyrazoles 1a,b. The synthesis and characterisation of these various polydentate ligands are described.     

Versatile synthesis of oxindole-1,3-dicarboxamides

A new, high-yielding synthesis of oxindole-1,3-dicarboxamides was elaborated starting from 1-phenoxycarbonyl-3-ethoxycarbonyl-2-oxindole and 1,3-diphenoxycarbonyl-2-oxindole. This method permits also the preparation of N,N,N′-tri- and N,N,N′,N′-tetrasubstituted oxidole-1,3-dicarboxamides, families of compounds that are unknown in the literature. The scope and limitations of the methodology have also been investigated, and a remarkable selectivity has been observed among the amines used in the amidation steps.