A convenient synthesis of nitro-substituted 1,2-benzisothiazol-3(2H)-one 1,1-dioxides (nitrosaccharins)

Nitro-substituted 1,2-benzisothiazol-3(2H)-one 1,1-dioxides (nitrosaccharins) have been synthesized by amminolysis of nitro 2-chlorosulfonylbenzoate esters. This method appears to have advantages over the original procedure of oxidation of an ortho-toluenesulfonamide.     

Efficient and selective deprotection method for N-protected 2(3H)-benzoxazolones and 2(3H)-benzothiazolones

Cyclic carbamate flanked with heterocyclic or aliphatic moieties are frequently used in medicinal chemistry. The synthesis of derivatives bearing a free NH often requires the use of a protection method. A literature search reveals very few protection/deprotection methods for cyclic carbamates. In this paper, we described different methods applicable to 2(3H)-benzoxazolone and 2(3H)-benzothiazolone.     

Synthesis of N,N′-disubstituted cyclic 1,2-diamines derived from (1R,2R)-1,2-diaminocyclohexane

The synthesis of N,N′-unsymmetrically tetrasubstituted cyclic 1,2-diamines derived from (1R,2R)-diaminocyclohexane is reported. We comment on the structural nature of these cyclic 1,2-diamines and discuss their characteristic features.     

Synthesis and derivatisation of N,N′-trisubstituted 1,2-diamines derived from (1R,2R)-1,2-diaminocyclohexane

The synthesis of N,N′-trisubstituted 1,2-diamines can be achieved by simple reduction of an aminal derived from (1R,2R)-diaminocyclohexane. We comment on the scope and limitation of this reduction and discuss its application towards the synthesis of unsymmetrical N,N′-tetrasubstituted 1,2-diamines.     

One-pot multistep synthesis of 3,4-fused isoquinolin-1(2H)-one analogs

We have developed a robust approach for the synthesis of 3,4-fused isoquinolin-1(2H)-one analogs. A benzonitrile or a nicotinonitrile bearing an ortho-substituent, such as -OH, -SH, or -NHR (R = alkyl or aryl) can be deprotonated by KOtBu and then reacted with methyl 2-(bromomethyl)benzoate (8) to form its corresponding O-, S-, or N-alkylation product. The product thus formed is then treated with KOtBu again to initiate a cascade process that will lead to the formation of its corresponding 3,4-fused isoquinolin-1(2H)-one. This multistep synthesis as well as the final product purification is achieved in a one-pot manner.     

Catalytic photocarboxylation of 1,1-diphenylethylene with N,N,N′,N′-tetramethylbenzidine and carbon dioxide

Photocarboxylation of 1,1-diphenylethylene with N,N,N′,N′-tetramethylbenzidine (TMB) in MeCN under bubbling of CO₂ proceeded with high catalytic efficiency, giving 3,3-diphenylacrylic acid (DPA) and 3-hydroxy-3,3-diphenylpropionic acid (20). The turnover number (TON=(DPA+20)/TMB) reached 17. Similarly, 1-phenyl-1-cyclohexene yielded cis-2-acetamido-2-phenylcyclohexanecarboxylic acid with TON 5.9. As compared with related N,N-dimethylaniline derivatives, TMB is more resistant to photodecomposition, has the much larger absorbance in the S₀→S₁ transition, and has the lower quenching efficiency by CO₂. Probably these factors are partly responsible for the high TON observed for TMB.     

N,N′-Diisopropyl- and N,N′-dicyclohexylthiourea cadmium(II) complexes as precursors for the synthesis of CdS nanoparticles

Crystals of the cadmium(II) complexes of N,N-diisopropylthiourea and N,N-dicyclohexylthiourea were obtained and their X-ray single crystal structures determined. These complexes are air-stable, easy to prepare and inexpensive and decompose cleanly to give good quality crystalline CdS. The nanoparticles of CdS thus obtained showed quantum confinement effects in their optical spectra, with close to band-edge emission in luminescence experiments. The broad diffraction patterns observed are typical of nanodimensional particles. The variation of concentration of precursor-to-HDA ratio change the isolated materials from spheres to rod-shaped. TEM images showed agglomerates of needle-like plate of particles.     

Mild and regioselective iodination of aromatic compounds with N,N′-diiodo-N,N′-1,2-ethanediylbis(p-toluenesulphonamide)

N,N′-Diiodo-N,N′-1,2-ethanediylbis(p-tolouenesulphonamide) [NIBTS] and catalytic trifluoroacetic acid can be used for the regioselective iodination of aromatic compounds in acetonitrile under mild conditions in excellent yields.     

Electrochemical and electrochromic properties of novel aromatic poly(amine-amide)s derived from N,N′-bis(4-carboxyphenyl)-N,N′-diphenyl-1,4-phenylenediamine

A series of novel triphenylamine-containing aromatic poly(amine-amide)s were prepared from the dicarboxylic acid, N,N′-bis(4-carboxyphenyl)-N,N′-diphenyl-1,4-phenylenediamine, and various diamines by direct phosphorylation polycondensation. All the poly(amine-amide)s were amorphous, soluble in a variety of organic solvents, and could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (195-280 °C). These polymers exhibited strong UV-Vis absorption bands at 330-346 nm and their photoluminescence showed maximum bands around 516-535 nm in NMP solution. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine-amide)s prepared by casting polymer solution onto an indium-tin oxide (ITO)-coated glass substrate exhibited two reversible oxidative redox couples at potential 0.73-0.78 V and 1.12-1.18 V, respectively vs Ag/AgCl in acetonitrile solution. All the poly(amine-amide)s exhibited excellent reversibility of electrochromic characteristics by continuous ten cyclic scans between 0.0 and 1.40 V, with a color change from original pale yellowish neutral form to the green and then to blue oxidized forms.     

Synthesis of diazafluorene- and diazafluorenone-N,N′-dioxides using HOF·CH3CN

A variety of diazafluorenes and diazafluorenones were oxidized using the HOF·CH₃CN complex to form the corresponding N,N′-dioxide derivatives under mild conditions. The products exhibit red-shift absorptions in the UV/visible spectrum relative to the parent compounds. Many such oxidations could not be achieved with any other oxygen-transfer agent.     

Dysoxylentin A, the first 21-nortriterpenoid bearing a 2-(propan-2-ylidenyl)furan-3(2H)-one, from Dysoxylum lenticellatum

Dysoxylentin A (1), the first 21-nortriterpenoid bearing a 2-(propan-2-ylidenyl)furan-3(2H)-one functional group was isolated from the stem of Dysoxylum lenticellatum. Its structure was elucidated by extensive spectroscopic analysis. A plausible biosynthetic pathway was postulated. Dysoxylentin A exhibited selective cytotoxicity against HL-60 tumor cell line.     

Efficient synthesis of N,N′-dialkyl-N″-dialkylaminocarbothioyl thioureas from cyclic secondary amines, CS2, and N,N′-dialkyl carbodiimides in water

A mild, convenient, and practical one-pot procedure for direct synthesis of N,N′-dialkyl-N″-dialkylaminocarbothioyl thioureas is described via three-component reaction of cyclic secondary amines, CS₂, and N,N′-dialkyl carbodiimides in water at room temperature.     

A concise synthesis of asymmetrical N,N′-disubstituted guanidines

We present a new and concise method for the preparation of asymmetrical N,N′-disubstituted guanidines starting from thiourea via the reaction of N-Boc-protected N′-alkyl/aryl substituted thioureas with an amine in the presence of mercury(II) chloride and triethylamine.     

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.     

Endo and exo cyclometallated iron carbonyl complexes derived from N-(N′-methyl-2-pyrrolylmethylidene)-2-thienylmethylamine

The reaction of N-(N′-methyl-2-pyrrolylmethylidene)-2-thienylmethylamine (1) with Fe₂(CO)₉ in refluxing toluene gives endo cyclometallated iron carbonyl complexes 2 and 5, exo cyclometallated iron carbonyl complex 3, and unexpected iron carbonyl complex 4. Complexes 2, 3, and 5 are geometric isomers. Complex 5 differs from complex 2 in the switch of the original substituent from α to β position of the pyrrolyl ring, and the pyrrolyl ring bridges to the diiron centers in μ-(3,2-η¹:η²) coordination mode in stead of μ-(2,3-η¹:η²). In complex 4, the pyrrolyl moiety of the original ligand 1 has been displaced by a thienyl group, which comes from the same ligand. Single crystals of 2, 3, and 5 were subjected to the X-ray diffraction analysis. The major product 2 undergoes: (i) thermolysis to recover the original ligand 1; (ii) reduction to form a hydrogenation product, 6, of the original ligand; (iii) substitution to form a monophosphine-substituted complex 7; (iv) chemical as well as electrochemical oxidation to produce a carbonylation product, γ-butyrolactam 8.     

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.