A Switchable Catalyst Duo for Acyl Transfer Proximity Catalysis and Regulation of Substrate Selectivity

Enzymes are encoded with a gamut of information to catalyze a highly selective transformation by selecting the proper reactants from an intricate mixture of constituents. Mimicking biological machinery, two switchable catalysts with differently sized cavities and allosteric control are conceived that allow complementary size-selective acyl transfer in an on/off manner by modulating the effective local concentration of the substrates. Selective activation of one of two catalysts in a mixture of reactants of similar reactivity enabled upregulation of the desired product.     

2-取代-4(3H)-喹唑啉酮在Br(o)nsted酸性功能化离子液体中的微波合成

以N-甲基咪唑、吡啶为起始原料,合成了二种新型Br(o)nsted酸性功能化离子液体:1-(4-磺酸基)苄基-3-甲基咪唑硫酸氢根盐(3a),N-(4-磺酸基)苄基吡啶硫酸氢根盐(3b),以其作为反应介质与催化剂,研究了2-取代-4(3H)-喹唑啉酮的三组分、一锅法微波合成.结果表明,当n(2-氨基苯甲酸):n(酰氯):n(乙酸铵):n(3a或3b)=1:1.2:1.5:0.1时,反应6 min即可完成,产率81%～95%.离子液体经减压蒸馏、真空干燥可重复使用3次,催化活性基本保持不变.     

2-取代-4(3H)-喹唑啉酮在BrФnsted酸性功能化离子液体中的微波合成

以N-甲基咪唑、吡啶为起始原料,合成了二种新型BrФnsted酸性功能化离子液体:1-(4-磺酸基)苄基-3-甲基咪唑硫酸氢根盐(3a),N-(4-磺酸基)苄基吡啶硫酸氢根盐(3b),以其作为反应介质与催化剂,研究了2-取代-4(3H)-喹唑啉酮的三组分、一锅法微波合成.结果表明,当n(2-氨基苯甲酸):n(酰氯):n(乙酸铵):n(3a或3b)=1:1.2:1.5:0.1时,反应6min即可完成,产率81%～95%.离子液体经减压蒸馏、真空干燥可重复使用3次,催化活性基本保持不变.     

HPVC皮带轮的注塑模设计与应用

针对HPVC皮带轮制件的结构与材料特点,给出了皮带轮合理的成型工艺及注射成型参数;对注塑模具的结构与工作过程、分型面选择、排气机构、模具成型件、浇注系统、脱模机构等作了详细的设计阐述,提出了该类模具设计的注意要点.     

Heteropoly acid supported on activated natural clay-catalyzed synthesis of 3,4-dihydropyrimidinones/thiones through Biginelli reaction under solvent-free conditions

Dihydropyrimidinones/thiones (DHPM’s) have been prepared by one-pot condensation of methyl acetoacetate, aldehydes, urea/thiourea in the presence of heteropoly-11-tungsto-1-vanadophosphoric acid, H₄[PVW₁₁O₄₀]?·?32H₂O, (HPV) supported on activated natural clay (HPVAC) under solvent-free reaction condition have been proposed. The DHPM derivatives were identified through elemental analysis and melting point measurements and characterized by FT-IR, ¹H-NMR, ¹³C-NMR spectroscopic methods.     

Microwave-assisted multicomponent reaction in water leading to highly regioselective formation of benzo[f]azulen-1-ones

Microwave-assisted three-component reaction has been established for the regioselective synthesis of benzo[f]azulen-1-ones. The reaction was performed in aqueous media under microwave irradiation by using readily available and inexpensive starting materials. A total of 38 examples were examined to show a broad substrate scope and good overall yields (70-89%). The present new synthesis shows attractive green chemistry characteristics, such as the use of water as reaction media, concise one-pot conditions, short reaction periods (7-24 min), easy work-up/purification, and reduced waste production without the use of any strong acids or metal promoters.     

Facile Synthesis and Crystal Structure of a Novel Cyanopyridine

The title compound 2-amino-4-(4-hydroxy-3,5-dimethoxyphenyl)-5-methyl-6-phenyl nicotinonitrile,C 21 H 19 N 3 O 3,was synthesized via four-component reactions between propio-phenone,malononitrile,syringaldehyde and ammonium acetate in ethanol under reflux without catalyst and characterized by IR,1 H NMR,13 C NMR,MS,EA and single-crystal X-ray diffraction.Single-crystal X-ray diffraction analysis shows that the compound is of monoclinic system,space group P2 1 /n with a=8.4600(17),b=17.139(3),c=13.408(3),β=107.06(3)°,V=1858.6(6)3,Z=4,M r=361.39,F(000)=760,μ(MoKα)=0.088 mm-1,D c=1.292 g/cm 3,λ=0.71073,the final R=0.0751 and wR=0.0938 for 3333 observed reflections with I > 2σ(I).The crystal packing of the title compound is stabilized by intermolecular hydrogen bonds.     

Immobilization of 1,4-Diazabicyclo[2.2.2]Octane (DABCO) over Mesoporous Silica SBA-15: An Efficient Approach for the Synthesis of Functionalized Spirochromenes

Immobilized 1,4-diazabicyclo[2.2.2]octane (DABCO) over mesoporous silica SBA-15 has been found to be an efficient heterogeneous base catalyst for the synthesis of biologically active functionalized spirochromene derivatives via three-component reaction of isatins/acenaphthoquinone, activated methylene reagents, and 1,3-dicarbonyl compounds in aqueous media. This ecofriendly protocol offers several advantages such as a cost-effective procedure with excellent yield, short reaction time, simple workup, recovery and reusability of catalyst, good functional group tolerance, and broad scope of usable substrates.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Solvent-free microwave activated three-component synthesis of thiazolo-s-triazine C-nucleosides

Novel three-component one-pot reactions of thiazole Schiff's bases, ammonium acetate and an aldose, under solvent-free microwave irradiation, expeditiously and diastereoselectively yield acyclic C-nucleosides incorporating the thiazolo-s-triazine structure as a nucleobase.