Isocyanide‐Based Three‐Component Synthesis of Highly Substituted 1,6‐Dihydro‐6,6‐dimethylpyrazine‐2,3‐dicarbonitrile, 3,4‐Dihydrobenzo[g]quinoxalin‐2‐amine,and 3,4‐Dihydro‐3,3‐dimethyl‐quinoxalin‐2‐amine Derivatives

A novel and efficient isocyanide‐based multicomponent reaction between alkyl or aryl isocyanides 1 , 2,3‐diaminomaleonitrile ( 2 ), naphthalene‐2,3‐diamines ( 6 ) or benzene‐1,2‐diamine ( 9 ), and 3‐oxopentanedioic acid ( 3 ) or Meldrum's acid ( 4 ) or ketones 7 was developed for the ecologic synthesis, at room temperature under mild conditions, of 1,6‐dihydropyrazine‐2,3‐dicarbonitriles 5a – 5f in H₂O without using any catalyst, and of 3,4‐dihydrobenzo[g]quinoxalin‐2‐amine and 3,4‐dihydro‐3,3‐dimethyl‐quinoxalin‐2‐amine derivatives 8a – 8g and 10a – 10e , respectively, in the presence of a catalytic amount of p‐toluenesulfonic acid (TsOH) in EtOH, in good to excellent yields (Scheme 1).     

A Convenient Synthesis of 2,3‐Dihydro‐4H‐thiopyrano[2,3‐b]‐, ‐[2,3‐c]‐, or ‐[3,2‐c]pyridin‐4‐ones by the Reaction of the Corresponding 1‐(Chloropyridinyl)alk‐2‐en‐1‐ones with NaSH

2,3‐Dihydro‐4H‐thiopyrano[2,3‐b]pyridin‐4‐ones 4 were prepared by a three‐step sequence from commercially available 2‐chloropyridine ( 1 ). Thus, successive treatment of 1 with ⁱPr₂NLi (LDA) and α,β‐unsaturated aldehydes gave 1‐(2‐chloropyridin‐3‐yl)alk‐2‐en‐1‐ols 2 , which were oxidized with MnO₂ to 1‐(2‐chloropyridin‐3‐yl)alk‐2‐en‐1‐ones 3 . The reactions of 3 with NaSH?n H₂O proceeded smoothly at 0° in DMF to provide the desired thiopyranopyridinones. Similarly, 2,3‐dihydro‐4H‐thiopyrano[2,3‐c]pyridin‐4‐ones 8 and 2,3‐dihydro‐4H‐thiopyrano[3,2‐c]pyridin‐4‐ones 12 were obtained starting from 3‐chloropyridine ( 5 ) and 4‐chloropyridine ( 9 ), respectively.     

Palladium(II) and Platinum(II) Complexes with Bisphosphanes, [S2C=C(CN)2]2– and [Se2C=C(CN)2]2– as Chelating Ligands

The palladium(II) and platin(II) 1, 1‐dicyanoethylene‐2, 2‐dithiolates [(L–L)M{S₂C=C(CN)₂}] (M = Pd: L–L = dppm, dppe, dcpe, dpmb; M = Pt: dppe, dcpe, dpmb) were prepared either from[(L–L)MCl₂] and K₂[S₂C=C(CN)₂] or from [(PPh₃)₂M{S₂C=C(CN)₂}] and the bisphosphane. Moreover, [(dppe)Pt{S₂C=C(CN)₂}]was obtained from [(1, 5‐C₈H₁₂)Pt{S₂C=C(CN)₂}] and dppeby ligand exchange. The 1, 1‐dicyanoethylene‐2, 2‐diselenolates[(dppe)M{Se₂C=C(CN)₂}] (M = Pd, Pt) were prepared from[(dppe)MCl₂] and K₂[Se₂C=C(CN)₂]. The oxidation potentials of the square‐planar palladium and platinum complexes were determined by cyclic voltammetry. The reaction of [(dcpe)Pd(S₂C=O)] with TCNE led to a ligand fragment exchange and gave the 1, 1‐dicyanoethylene‐2, 2‐dithiolate [(dcpe)Pd{S₂C=C(CN)₂}] in good yield.     

Synthesis of Nitro‐Octaaza Derivatives of Reduced Anthracene

Nitro compounds of octaaza derivatives of reduced anthracene were synthesized for the first time by reaction of 2,3,4a,6,7,8a,9,10‐octaaza‐4,8‐dioxo‐3,4,4a,7,8,8a,9,9a,10,10a‐decahydroanthracene with nitric acid, mixed nitric acid/sulfuric acid, and nitric acid/acetic anhydride at between –20 and –30 °C. In addition, 1,2,4,5‐tetrazine azido derivatives were obtained by hydrolytic decomposition of the starting compound by nitrous acid. All the resultant compounds exhibit high thermal stability.     

Beiträge zur Chemie des Phosphors. 245 [1], LiP7(BNEt2)2 und P7(BNEt2)4Cl: Zwei neuartige polycyclische Boraphosphane

Contributions to the Chemistry of Phosphorus. 245, LiP₇(BNEt₂)₂ and P₇(BNEt₂)₄Cl: Two Novel Polycyclic Boraphosphanes The directed synthesis of a noval tetracyclic heteropolyphosphane skeleton from a tricyclophosphane has been achieved by condensation of Li₃P₇ · 3DME with Cl(Et₂N)B‐B(NEt₂)Cl to the diboranonaphosphanide LiP₇(BNEt₂)₂ ( 1 ). When the reaction proceeds the mixed‐substituted diboranonaphosphane P₇(BNEt₂)₄Cl ( 2 ) is formed. According to their ³¹P NMR spectra 1 and 2 possess a B₂P₇(3) skeleton analogous to that of the hydrocarbon deltacyclane. Additional weak signals in the ³¹P NMR spectrum of 2 indicate that also small amounts of the symmetrically substituted diborane(4) P₁₄B₆(NEt₂)₆ ( 3 ) are formed.     

Efficient Synthesis of a Styryl Analogue of (2S,3R,4E)‐N2‐Octadecanoyl‐4‐tetradecasphingenine via Cross‐Metathesis Reaction

The first total synthesis of sphingolipid (2S,3R,4E)‐N²‐octadecanoyl‐4‐tetradecasphingenine ( 1a ), a natural sphingolipid isolated from Bombycis Corpus 101A, and of its styryl analogue 1b was achieved in good overall yield (Schemes 1 and 2). The key step involved the installation with (E) stereoselectivity of a long lipophilic chain or phenyl group on allyl alcohol derivative 3 via a cross‐metathesis reaction (→ 5a or 5b ). The N‐Boc protected 3 was easily accessible from (S)‐Garner aldehyde.     

Copper‐Catalyzed Tandem Synthesis of Functionalized Sulfonyl‐yn‐imines from Sodium Arylsulfinates,Trichloroacetonitrile, and Terminal Alkynes

A one‐pot synthesis of functionalized sulfonyl‐yn‐imines via a Cu‐catalyzed tandem reaction of sodium arylsulfinates, trichloroacetonitrile, and terminal alkynes has been developed.     

Synthesis of 4‐Arylisocoumarins (=4‐Aryl‐1H‐2‐benzopyran‐1‐ones) through Acidic Hydrolysis of (Z)‐2‐(1‐Aryl‐2‐methoxyethenyl)benzaldehydes,Followed by Oxidation

4‐Arylisocoumarins (=4‐aryl‐1H‐2‐benzopyran‐1‐ones) 6 were prepared from 2‐(1‐aryl‐2‐methoxyethenyl)‐1‐bromobenzenes 1 . Successive treatment of these bromo styrenes with BuLi and 1‐formylpiperidine gave a mixture of (E)‐ and (Z)‐2‐(1‐aryl‐2‐methoxyethenyl)benzaldehydes 2 . Hydrolysis of (Z)‐isomers with conc. HBr, followed by pyridinium chlorochromate (PCC) oxidation of the resulting 1H‐2‐benzopyran‐1‐ol derivatives 4 (and 5 ), afforded the desired products.     

A Facile Synthesis of 1‐Substituted 3‐Alkoxy‐1H‐isoindoles Based on the Reaction of 2‐(Dialkoxymethyl)phenyllithiums with Nitriles,Followed by Acid‐Catalyzed Cyclization

A two‐step synthesis of 1‐substituted 3‐alkoxy‐1H‐isoindoles 4 has been developed. Thus, the reaction of 2‐(dialkoxymethyl)phenyllithium compounds, which are easily generated in situ by Br/Li exchange between 1‐bromo‐2‐(dialkoxymethyl)benzenes 1 and BuLi in THF at ?78°, with nitriles afforded [2‐(dialkoxymethyl)phenyl]methanimines 2 , which were treated with a catalytic amount of TsOH?H₂O in refluxing CHCl₃ to give the desired products in reasonable yields. Similarly, 3‐aryl‐1‐ethoxy‐1‐methyl‐1H‐isoindoles 7 have been prepared starting from 1‐bromo‐2‐(1,1‐diethoxyethyl)benzenes 5 .     

Synthesis of 4‐Aryl‐8‐fluoro‐3a,4,5,9b‐tetrahydro‐3H‐cyclopenta[c]quinolines and Their Ozonides

4‐Aryl‐8‐fluoro‐3a,4,5,9b‐tetrahydro‐3H‐cyclopenta[c]quinolines are synthesized by acid‐catalyzed (CF₃CO₂H) three‐component cyclocondensation of 4‐fluoroaniline with aromatic aldehydes and cyclopentadiene. Stable ozonides with (1R*,4S*,5aR*,6S*,11bS*)‐configurations are obtained by ozonolysis of corresponding trifluoroacetyl derivatives.     

Cyclization of (2‐Alkenylphenyl)carbonyl Compounds to Polycyclic Arenes Catalyzed by Copper(II) Trifluoromethanesulfonate or Trifluoromethanesulfuric Acid

Various polycyclic arenes, such as naphthalenes, tetrahydroantharacenes, tetrahydrotetracenes, dihydropentacenes, and dihydropentaphenes are prepared from 2‐alkenylphenyl ketones and aldehydes by the catalytic use of copper(II) trifluoromethanesulfonate (Cu(OTf)₂) or trifluoromethanesulfuric acid (TfOH).     

Synthesis of 4,6‐Dimethyldibenzothiophene and 1,2,3,4‐Tetrahydro‐4,6‐dimethyldibenzothiophene via Tilak Annulation

1,2,3,4‐Tetrahydro‐4,6‐dimethyldibenzothiophene was prepared by coupling 2‐bromo‐3‐methylcyclohexanone with 2‐methylbenzenethiol and annulating the product with the aid of polyphosphoric acid. A mixture of 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene and 4,6‐dimethyldibenzothiophene was prepared by coupling 2‐bromo‐3‐methylcyclohex‐2‐en‐1‐one with 2‐methylbenzenethiol and annulating the product with the aid of polyphosphoric acid. 2‐Bromo‐3‐methylcyclohexanone was synthesized by conjugate addition of Me₃Al to 2‐bromocyclohex‐2‐en‐1‐one with CuBr as catalyst and 2‐bromo‐3‐methylcyclohex‐2‐en‐1‐one by bromination? elimination of 3‐methylcyclohex‐2‐en‐1‐one. 1,2,3,4,4a,9b‐Hexahydro‐4,6‐dimethyldibenzothiophene was prepared by reduction of 1,2,3,4‐tetrahydro‐4,6‐dimethyldibenzothiophene with Zn and CF₃COOH.     

Synthesis and Transformation of Methyl 2‐(6‐Hydroxy‐2‐phenylpyrimidin‐4‐yl)acetate: Simple Preparation of Pyrimidines with Heterocyclic Substituents

A simple and efficient synthesis of four new substituted pyrimidines, compounds 9a – d , from the title compound 3 is described. Conversion of 3 to methyl (E)‐3‐(dimethylamino)‐2‐(6‐methoxy‐2‐phenylpyrimidin‐4‐yl)prop‐2‐enoate ( 4 ), followed by condensation with various dinucleophiles according to the ‘enaminone methodology’, afforded the target compounds 9 in medium‐to‐good yields.     

Stereoselective Total Synthesis of the Natural Oxylipin (6R,7E,9R,10S)‐6,9,10‐Trihydroxyoctadec‐7‐enoic Acid

The stereoselective total synthesis of the natural oxylipin, (6R,7E,9R,10S)‐6,9,10‐trihydroxyoctadec‐7‐enoic acid, has been accomplished using nonanal and hexane‐1,6‐diol as the starting materials. The synthesis involves Sharpless kinetic resolution, asymmetric epoxidation, and olefin cross‐metathesis as the key steps.     

Synthesis and characterization of a microsphere‐based coating for textiles with potential as an in situ bioactive delivery system

Proteinaceous microspheres have a wide range of biomedical applications, including their use as drug delivery systems. On the other hand, bioactive and antimicrobial textiles are promising substrates for medical care, in particular, as wound‐dressings. This work relates the development of a new process for the functionalization of textiles through the simultaneous formation and linkage of protein‐based microspheres onto textile fibers by sonochemical techniques. The microspheres developed by this process possess antimicrobial properties by themselves, but other may be incorporated by the encapsulation of various pharmaceutical formulations. This new type of microspheres and particularly their fixation onto textile materials encourage the development of textiles that can be used as delivery systems in a simple, fast, and non‐toxic process. Here it is reported the production of microspheres with a combination of bovine serum albumin (BSA), L ‐Cysteine (L ‐Cys), and n‐dodecane, using the ultrasound technology. The size distribution and morphology of the microspheres was determined as a function of several parameters such as irradiation time and BSA and L ‐Cys concentrations. The produced microspheres were analyzed using a laser light scattering size analyzer, an optical microscope and a scanning electron microscope. The new coating of BSA + L ‐Cys microspheres revealed a high stability and excellent antibacterial properties being a promising alternative to design textile‐based bioactive delivery systems with potential application in the development of textile‐based wound‐dressings. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and Antibacterial Activity of 3‐(5‐Methylisoxazol‐3‐yl) −1,2,4‐triazolo [3,4‐b]‐1,3,4‐thiadiazine Derivatives

The condensed products 2‐10 of 4‐amino‐5‐mercapto‐3‐(5‐methylisoxazol‐3‐yl)‐l,2,4‐triazole (1) with chloroacetaldehyde, 2‐bromocyclohexanone, chloranil, ωbromo‐ω‐(1H‐1, 2,4‐triazol‐l‐yl)acetophenone, 2‐bromo‐4′‐substituted acetophenones and 2‐bromo‐6′‐methoxy‐2′‐acetonaphthone were described. The antibacterial activities were also evaluated.