Synthesis of symmetrical 1, 3-diynes via tandem reaction of (Z)-arylvinyl bromides in the presence of DBU and CuI

Microwave-assisted tandem reaction of(Z)-arylvinyl bromides involving an elimination and homocoupling in the presence of DBU and Cul in DMF affords a variety of symmetrical 1,3-diynes in good to excellent yields.This tandem process,eliminating the need of volatile and savory terminal alkynes,provides an alternative to the conventional homocoupling methods for the synthesis of symmetrical 1,3-diynes.     

Coupling of 3,8-Dibromo-1,10-phenanthroline with 3,5-Diethynylheptyloxybenzene: A Suzuki/Miyaura Versus a Sonogashira Perspective

Abstract

We report a new application of the Suzuki-Miyaura reaction whereas two bifunctional reactants, 3,8-dibromo-1,10-phenanthroline and 3,5-diethynylheptyloxylbenzene (9), yield 3,8-bis(3-ethynyl-5-heptyloxyphenylethynyl)-1,10-phenanthroline (2) efficiently (74% yield) without polymerization. This was achieved by reacting a stoichiometric amount of 9 and (Me₃Si)₂NLi to obtain quantitatively the monoacetylide anion of 9 (10). The latter was activated with B-methoxy-9-BBN and reacted in analogy to the alkynyl copper complex of a Sonogashira route. However, in the Sonogashira reaction, the alkynyl copper complex is present in small equilibrium concentrations and polymerization takes place even when reagents are mixed slowly. Actually the Sonogashira route gave no desired product 2, as the latter polymerizes easily via homo-coupling in the presence of air and Cu(I).     

Straightforward Method for the Preparation of Lysine-Based Double-Chained Anionic Surfactants

Double-chained surfactants with potential biocompatibility have been prepared in high yields by lysine acylation with four natural saturated fatty acids (C₆ to C₁₂) and with cis-undec-5-enoic acid. The surfactants were found to assemble into nanotubules in aqueous medium and, when mixed with a commercial cationic surfactant, to spontaneously form liposomes.     

A Ring Expansion Strategy in Antiviral Synthesis: A Novel Approach to TAK‐779

Abstract

A synthesis of TAK‐779 that relies on construction of a key carboxylic acid intermediate by a ring expansion with TMSCHN₂ is described.     

Synthesis of 1,4,5-trisubstituted-1,2,3-triazoles via coupling reaction of diaminomaleonitrile with aromatic diazonium salts

A mild procedure for the preparation of 2-(5-amino-1-aryl-1H-1,2,3-triazol-4-yl)-2-iminoacetonitriles and 2-(5-amino-1-aryl-1H-1,2,3-triazol-4-yl)-2-oxoacetonitriles was achieved by the reaction of diaminomaleonitrile and phenyl/substituted phenyl diazonium chlorides. 4-Nitrophenyl diazonium chloride afforded 2-amino-3-(3-(4-nitrophenyl)triaz-1-en-1-yl)maleonitrile. Triazole iminoacetonitrile and maleonitrile derivatives were reacted further with excess acetone and benzaldehyde with a catalytic amount of 1,8-diazabicyclo[5.4.0]undec-7-ene to yield 5-(5-imino-2,2-dimethyl-2,5-dihydrooxazol-4-yl)-3-aryl-3H-1,2,3-triazol-4-amine and (E)-N-benzylidene-5-(5-imino-2-aryl-2,5-dihydrooxazol-4-yl)-3-aryl-3H-1,2,3-triazol-4-amine, respectively. Two competitive reactions, i.e., nucleophilic substitution and nucleophilic addition, were observed when triazole oxoacetonitrile and maleonitrile derivatives were reacted with hydroxylamine hydrochloride in the presence of sodium acetate.     

A silver(I)-catalyzed reaction of 2-alkynylbenzaldoxime with arylsulfonyl chloride

A silver-catalyzed reaction of 2-alkynylbenzaldoxime with arylsulfonyl chloride proceeds smoothly at room temperature to afford 4-tosyloxyisoquinolines in moderate to good yields. Additionally, the resulting 4-tosyloxyisoquinolines could be further elaborated through palladium-catalyzed coupling reactions leading to diverse isoquinolines.     

Mild addition of carbon nucleophiles to pyridine and quinoline N-oxides under different activation conditions

In the course of our syntheses of functionalised pyridine and quinoline derivatives, we examined the reactivities of pyridine and quinoline N-oxides towards the nucleophilic addition of acidic carbon derivatives. Different activating reagents were used, such as PyBroP, triflic anhydride and a combination of pyrrolidine phosphoramide and triflic anhydride.     

Synthesis of Star-like Polybutadienes by a Combination of Living Anionic Polymerization and “Click” Coupling Method

Three-arm and four-arm star-like polybutadienes(PBds) were synthesized via the combination of living anionic polymerization and the click coupling method. Kinetic study showed that the click reaction between the azido group terminated PBd-t-N3 and the alkyne-containing multifunctional linking reagent was fast and highly efficient. All coupling reactions were fully accomplished within 40 min at 50 °C in toluene in the presence of the reducing agent Cu(0), proven by 1H-NMR, FTIR and GPC measurements. For the coupling reactions between the PBd-t-N3 polymer and dialkyne-containing compound, the final conversion of the coupled PBd-PBd polymer was ca. 97.0%. When a PBd-t-N3 polymer was reacted with trialkyne-containing or tetraalkyne-containing compound, the conversion of three-arm or four-arm PBd was around 95.5% or 87.0%, respectively. Several factors influencing the coupling efficiency were studied, including the molecular weight of the initial PBd-t-N3, arm numbers and the molar ratio of the azido group to the alkynyl group. The results indicated that the conversion of the target products would be promoted when the molecular weight of the PBd-t-N3 was low and the molar ratio of the azido to alkynyl groups was close to 1.     

锰催化的C?C键生成反应研究进展

迄今为止,贵金属(铑、钯、钌等)在过渡金属催化的碳碳键生成反应中发挥着主导作用,然而使用廉价金属催化剂更符合可持续发展的要求。锰是地壳中含量排第三位的过渡金属,价格便宜,环境危害性小,有潜力成为贵金属催化剂的替代品并发挥其自身独特的反应性。尽管锰参与的当量反应有大量文献报道,目前锰催化的反应尤其是碳碳键生成反应的发展还不成熟,如何实现高效的催化循环是锰催化领域面临的主要难题之一。本文对锰催化的付-克烷基化反应、格氏试剂的酰化反应、偶联反应、碳金属化反应、自由基反应和碳氢键活化反应进行了综述。