Synthesis and stereochemistry of ω-azolylalkenes [1]

ω-Azolylalkenes 3, 4, and 5 were synthesized by N-alkylation of C-alkylation of ω-bromoalkenes 2, which were obtained either by phase transfer Wittig reactions of ω-bromoalkylphosphonium salts 1 with aldehydes or by Wittig reactions of ω-hydroxyalkylphosphonium salts 6 with aldehydes and subsequent bromination. ω-Azolylalkenes 3 were also directly prepared by the Wittig reaction of ω-azolylalkyltriphenylphosphonium salts 8 with aromatic aldehydes. The stereochemistry of these Wittig reactions was studied. © 1997 John Wiley & Sons, Inc.     

FeCI3‐promoted [3+3] cycloaddition: Efficient preparation of 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxylate and 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxamide derivatives

A facile approach was developed on assembly of the 2‐pyridone nucleus by ferric chloride promoted [3+3] cycloaddition in propionic acid. The tandem process involves cyclization of Michael adduct followed by aromatization. Thus, different substituted 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxylate and 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxamide derivatives were prepared in good yields from various enones with malonamic ester and malonamide, respectively     

Synthesis and intramolecular cyclization of 2‐methylsulfany‐4‐oxo‐3(4H)‐quinazolinyl)acetohydrazide

Treatment of ambident sodium salt of 2‐methylsulfanyl‐4(3H)‐quinazolinone with methyl bromoacetate resulted in N₍₃₎‐alkyl ester formation. Reaction of the resulted ester with hydrazine hydrate gave 2‐methylsulfanyl‐4‐oxo‐3(4H)‐quinazolinyl)acetohydrazide, which underwent intramolecular cyclization under heating in dimethylformamide to give 1‐aminoimidazo[2,1‐b]quinazoline‐2,5(1H,3H)‐dione. The latter took place in acylation reaction and in condensation with aromatic aldehydes.     

Synthesis and reactions of 3‐cyano‐4,6‐dimethyl‐2‐pyridone

Rapid synthesis of 3‐cyano‐4,6‐dimethyl‐2‐pyridone 3 , using piprazine as a catalyst was reported. X‐ray data of the 4,6‐dimethyl‐2‐oxo‐1,2‐dihydropyridine‐3‐carbonitrile exhibited its oxo form. Synthesis of isoquinolinecarbonitrile and pyridylpyridazine using compound 3 was investigated. Reactivity of the synthesized pyridone toward different organic reagents was also studied. J. Heterocyclic Chem., (2011).     

Some nucleophilic substitutions in 2‐cyano‐3‐nitroimidazo[1,2‐a]pyridine

In some nucleophilic substitution reactions of 2‐cyano‐3‐nitroimidazo[1,2‐a]pyridine, nitrogen (alkylamines, guanidine) and oxygen nucleophiles (alkoxides) underwent substitution of the 2‐cyano group, while sulfur nucleophiles (alkylthiols) underwent substitution of the 3‐nitro group.     

端位苯甲羧取代单苯环取代全氟二苯乙炔类化合物的合成及液晶性研究

本文设计合成了四类端位4-氰基和4-硝基苯甲羧取代的二苯乙炔类化合物，并通过DSC和偏光显微镜对它们的液晶性进行了研究。讨论了二苯乙炔核中全氟亚苯基的左右位置对液晶性的影响，比较了氰基取代和硝基取代的苯甲羧二苯乙炔类化合物的液晶性差异。     

Synthesis and chemical reactivity of 3‐oxo‐2‐arylhydrazono‐propanenitriles

2‐Formyl‐2‐arylhydrazonoethanenitriles 6b‐d where prepared via reacting enaminonitrile 2b,c with aromatic diazonium salts. These reacted with phenylhydrazine to yield bis hydrazones that were converted to arylazopyr‐azoles via a novel Vilsmeier‐Haack reaction type. Reaction of 6c with hydroxylamine afforded oxime that could be successfully cyclised into arylazoisoxazole. Reaction of 6c with hydrazine hydrate to yield arylazoamino‐pyrazole that proved to be excellent precursors for synthesis functional substituted pyrazolopyrimidines.     

Catalytic Asymmetric Intramolecular Hydroarylations of ω‐Aryloxy‐ and Arylamino‐Tethered α,β‐Unsaturated Aldehydes

Economical approach : The first organocatalytic asymmetric intramolecular hydroarylation of phenol‐ and aniline‐derived enals offers one of the most straightforward and atom‐economic approaches to enantioriched chromans and tetrahydroquinolines (up to 96 % ee; see scheme).

     

Synthesis of 1‐Amino‐5,6‐diaryl‐3‐cyano‐1H‐pyridin‐2‐ones and 6,7‐Diaryl‐4‐cyano‐3‐hydroxy‐1H‐[1,2]diazepines from Isoflavones

The one‐step cyclocondensation of substituted isoflavones (=3‐phenyl‐4H‐1‐benzopyran‐4‐ones) with cyanoacetohydrazide in the presence of KOH afforded a mixture of 1‐amino‐5,6‐diaryl‐3‐cyano‐1H‐2‐pyridin‐2‐ones and 6,7‐diaryl‐4‐cyano‐3‐hydroxy‐1H‐[1,2]diazepines.     

Kinetic simulations for cyclization of α,ω‐telechelic polymers

In this work, we conducted kinetic simulations to examine the effects of various experimental conditions on cyclization during the feed of α,ω‐telechelic polymers into a reaction mixture. The simulations showed that the interplay between the feed rate and rate coefficients for cyclization and multiblock formation were the dominant and controlling parameters. The simulations were in good agreement with previously published results on cyclization of α,ω‐telechelic polystyrene with different molecular weights by the Cu‐catalyzed azide/alkyne cycloaddition (CuAAC) reaction. They also showed that high dilution was not a necessary condition for cyclization and that high percentages of monocyclic could be rapidly produced in solutions that are more concentrated. Previously reported work demonstrated that cyclic polystyrene could be prepared in less than 9 min at 25 °C using the CuAAC “click” reaction. These simulations allow for optimization and better experimental design, leading to the possibility of large scale production of cyclic polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Intramolecular cyclization of ethyl ω-(5-amino-4-aminocarbonylimidazol-1-yl)carboxylates

Attempted elaboration of the title compounds to purines by reaction with ethyl formate leads instead to some novel fused imidazoles by intramolecular cyclization.     

Diastereo‐ and Enantioselective Intramolecular [2+2] Photocycloaddition Reactions of 3‐(ω′‐Alkenyl)‐ and 3‐(ω′‐Alkenyloxy)‐Substituted 5,6‐Dihydro‐1H‐pyridin‐2‐ones

3‐(ω′‐Alkenyl)‐substituted 5,6‐dihydro‐1H‐pyridin‐2‐ones 2 – 4 were prepared as photocycloaddition precursors either by cross‐coupling from 3‐iodo‐5,6‐dihydro‐1H‐pyridin‐2‐one ( 8 ) or—more favorably—from the corresponding α‐(ω′‐alkenyl)‐substituted δ‐valerolactams 9 – 11 by a selenylation/elimination sequence (56–62 % overall yield). 3‐(ω′‐Alkenyloxy)‐substituted 5,6‐dihydro‐1H‐pyridin‐2‐ones 5 and 6 were accessible in 43 and 37 % overall yield from 3‐diazopiperidin‐2‐one ( 15 ) by an α,α‐chloroselenylation reaction at the 3‐position followed by nucleophilic displacement of a chloride ion with an ω‐alkenolate and oxidative elimination of selenoxide. Upon irradiation at λ=254 nm, the precursor compounds underwent a clean intramolecular [2+2] photocycloaddition reaction. Substrates 2 and 5 , tethered by a two‐atom chain, exclusively delivered the respective crossed products 19 and 20 , and substrates 3 , 5 , and 6 , tethered by longer chains, gave the straight products 21 – 23 . The completely regio‐ and diastereoselective photocycloaddition reactions proceeded in 63–83 % yield. Irradiation in the presence of the chiral templates (?)‐ 1 and (+)‐ 31 at ?75 °C in toluene rendered the reactions enantioselective with selectivities varying between 40 and 85 % ee. Truncated template rac‐ 31 was prepared as a noranalogue of the well‐established template 1 in eight steps and 56 % yield from the Kemp triacid ( 24 ). Subsequent resolution delivered the enantiomerically pure templates (?)‐ 31 and (+)‐ 31 . The outcome of the reactions is compared to the results achieved with 4‐substituted 5,6‐dihydro‐1H‐pyridin‐2‐ones and quinolones.     

1,2‐Ph2‐9‐I‐1,2‐closo‐C2B10H9

The title compound, 9‐iodo‐1,2‐di­phenyl‐1,2‐dicarba‐closo‐dodecaborane(9), C₁₄H₁₉B₁₀I, has the expected pseudo‐icosahedral cluster geometry, with a cage C—C distance of 1.724 (4) Å, comparable to that in the non‐iodinated parent. However, the twist angles, θ, of the phenyl rings are 2.1 (6) and 27.6 (5)°, the latter being unusually large.     

Potassium 3‐cyano‐4‐(dicyanomethylene)‐5‐oxo‐4,5‐dihydro‐1H‐pyrrol‐2‐olate

The crystal structure of the title potassium salt, K⁺·C₈HN₄O₂⁻, of the organic anion 3‐cyano‐4‐(di­cyano­methyl­ene)‐5‐oxo‐4,5‐di­hydro‐1H‐pyrrol‐2‐olate shows that the di­cyano­methyl­ene moiety is able to accept an electron in the same way as does tetra­cyano­ethyl­ene, to yield the novel product. The organic anion is nearly planar, with deviations caused by steric crowding among the exocyclic cyano groups. The K⁺ cations lie within tricapped trigonal prisms that stack to form channels. The three‐dimensional structure is completed by the formation of hydrogen‐bonded chains by the anions.     

Synthesis of 1,3‐Dihydro‐3‐oxo‐2‐benzofuran‐1‐carboxylates via Intramolecular Cyclization of 2‐[2‐(Dimethoxymethyl)phenyl]‐ 2‐hydroxyalkanoates Followed by Oxidation

A novel and efficient method for the preparation of 1,3‐dihydro‐3‐oxo‐2‐benzofuran‐1‐carboxylates 4 under mild conditions has been developed. Thus, the reaction of [2‐(dimethoxymethyl)phenyl]lithiums, generated easily from 1‐bromo‐2‐(dimethoxymethyl)benzenes 1 , with α‐keto esters gives the corresponding 2‐[2‐(dimethoxymethyl)phenyl]‐2‐hydroxyalkanoates 2 . The TsOH‐catalyzed cyclization of these hydroxy acetals is followed by the oxidation of the resulting cyclic acetals 3 with PCC to give the desired products in satisfactory yields. The reaction of [2‐(dimethoxymethyl)‐4,5‐dimethoxyphenyl]lithium with (MeOC?O)₂, followed by treatment with NaBH₄ or organolithiums, affords 2‐[2‐(dimethoxymethyl)‐4,5‐dimethoxyphenyl]‐2‐hydroxyalkanoates 6 , which can similarly be transformed into the corresponding 1,3‐dihydro‐3‐oxo‐2‐benzofuran‐1‐carboxylates 7 in reasonable yields.     

Tetra­piperidinium di‐μ‐methoxy‐di‐μ5‐oxo‐tetra‐μ3‐oxo‐dodeca‐μ2‐oxo‐octa­oxodeca­vanadate

The structure of the title compound, (C₅H₁₂N)₄[V₁₀O₂₆(CH₃O)₂], reveals the presence of four protonated piperidin­ium cations and a [{V₁₀O₂₆}(OCH₃)₂]⁴⁻ polyanion having an embedded centre of inversion. The compound is distinguished by presenting, in contrast with other anionic deca­vanadates, two meth­oxy groups bridging the outermost V atoms, and it becomes the first example of this type among reported deca­vanadates.