水中取代水杨醛和氰乙酸酯的反应研究

以水杨醛和氰乙酸酯为原料, 以水为溶剂, 以三乙基苄基氯化铵为催化剂在不同的反应温度下合成了两个系列的色烯衍生物, 该方法具有反应条件温和、立体选择性好、产率高等优点.     

Surprisingly mild "enolate-counterion-free"pd(0)-catalyzed intramolecular allylic alkylations

[reaction: see text] Palladium-catalyzed intramolecular allylic alkylations of unsaturated EWG-activated amides can take place under phase-transfer conditions or in the presence of a crown ether. These new reaction conditions are milder and higher yielding than those previously reported. A rationalization for such an unexpected result is put forth and validated by DFT-B3LYP calculations. The results suggest cyclization via a counterion-free (E)-enolate TS.     

Highly stable Cp*-Ir(III) complexes with N-heterocyclic carbene ligands as C-H activation catalysts for the deuteration of organic molecules

The preparation of a series of complexes of the type CpIrX2(NHC) provides effective catalysts for the H/D exchange of a wide range of organic molecules in methanol-d4. The reaction proceeds with higher yields under milder reaction conditions than previous CpIr systems reported thus far. For comparative purposes, we also studied the catalytic activity of CpIrCl2(PMe3) under the same reaction conditions. The molecular structures of two of the new CpIr(NHC) complexes are described.     

Selective hydroformylation of various olefins using diphosphinite ligands

Novel diphosphinite ligands are synthesized by the reaction of various derivatives of 1,3‐diols with chlorodiphenylphosphine. The synthesized ligands exhibited considerable impact on hydroformylation of various olefins with excellent regioselectivity toward branched aldehyde. The effect of solvent, temperature, pressure and catalyst loading on the hydroformylation reaction is also described. The synthesized diphosphinite ligands with rhodium precursor works under milder reaction conditions as compared to traditional phosphine and phosphite‐based ligands. Copyright © 2013 John Wiley & Sons, Ltd.     

Copper-catalyzed N-alkylation of amides and amines with alcohols employing the aerobic relay race methodology

By employing aerobic oxidation to aldehydes as a more effective alcohol activation strategy, we developed a green Cu-catalyzed N-alkylation method for various amides and amines with alcohols. This reaction is more advantageous than the literature methods for it uses a ligand-free copper catalyst, can be readily carried out under milder aerobic conditions and generates water as the only byproduct. More importantly, based on our mechanistic studies and also supported by the literature, rather than following the previously-proposed mechanisms, we deduce that the newly-proposed relay race process should be the most possible and a more rational mechanism for the reactions, especially under aerobic conditions.     

Phosphorylation of alcohols with N-phosphoryl oxazolidinones employing copper(II) triflate catalysis

[reaction: see text]. Phosphoryl transfer from N-phosphoryl 5,5-diphenyl oxazolidinone is efficiently catalyzed by copper(II) triflate. The utility of this method has been demonstrated in the phosphorylation of representative primary, secondary, tertiary, phenolic, and allylic alcohols. These reaction conditions are significantly milder than employing alkoxides and allow the phosphorylation of biologically relevant molecules.     

含氟对称1-芳基-1,1-双酰胺类化合物的制备及其晶体结构研究

本文通过室温下三氟乙酰胺、一溴二氟乙酰胺或含氟的苯甲酰胺与芳醛在三氟甲磺酸和亚硫酰氯存在下的反应,高产率的制备了含氟对称1-芳基-1,1-双酰胺类化合物(RfCONH)2CHAr 。化合物3aa和3ab的结构通过X-射线衍射分析得到进一步确证。     

Diels-Alder reaction of maldoxin with an isopropenylallene

The Diels-Alder reaction of maldoxin with an isopropenylallene at 60-75 °C afforded an adduct closely related to chloropestolide A (24%) and a second adduct (0-11%) that underwent an ene reaction to generate the chloropupukeanolide D (11-22%) skeleton. The Diels-Alder reaction occurred with good selectively (>5:1) from a single face of maldoxin under much milder conditions than previously reported for the analogous dimethoxycyclohexadienone. Furthermore, the ene reaction took place under mild conditions, whereas the analogous Diels-Alder adduct from the dimethoxycyclohexadienone did not undergo an ene reaction.     

Efficient and eco-friendly synthesis of 2-amino-4H-chromene derivatives using catalytic amount of tetrabutylammonium chloride (TBAC) in water and solvent-free conditions

A simple, efficient and eco-friendly procedure has been developed using tetrabutylammonium chloride as catalyst for the synthesis of 2-amino-4H-chromene derivatives in water and solvent-free neat conditions. The present methodology offers several advantages such as excellent yields, short reaction time and environmentally benign milder reaction conditions.     

Kinetic Comparison of Trifluoroacetic Acid Cleavage Reactions of Resin-Bound Carbamates, Ureas, Secondary Amides, and Sulfonamides from Benzyl-, Benzhydryl-, and Indole-Based Linkers

The kinetics of cleavage reactions of 16 resin-bound carbamates, ureas, secondary amides, and sulfonamides from four different acid labile linkers including benzyl, benzhydryl, and indole linkers has been investigated. The optimized cleavage conditions are generally milder than those commonly used and reported (e.g., 0.5% TFA as opposed to 5%). Among various linkers studied in this work, the indole linker has been found to be the most acid labile followed by the Rink linker. The rate of cleavage of compounds linked to the resin via various functional groups can be summarized as follows: sulfonamide >carbamate approximately urea > amide. This study shows that cleavages of 16 compounds from four different acid labile linkers have been optimized to much milder conditions in terms of TFA concentration and the reaction time. It also demonstrates that single bead FTIR is an effective tool for optimizing cleavage conditions.     

A mild and efficient synthesis of 4-quinolones and quinolone heterocycles

The cycloacylation of aniline derivatives to 4-quinolones in the presence of Eaton's reagent is described. This high-yielding methodology is applicable to a wide variety of functionalized anilines and requires milder conditions than those traditionally employed. This cyclization protocol is used to prepare a host of heterocycles and bis-quinolones and is characterized by relatively low reaction temperature and ease of product isolation.     

Hydrides,Amides and Imides Mediated Ammonia Synthesis and Decomposition

Ammonia is feeding nearly half the world population and also holds the promise as a carbon‐free energy carrier. The development of ammonia synthesis and decomposition processes under milder conditions is a grand challenge for more than a century. Increasing effort is devoted to this area in recent years and encouraging progress has been achieved. In this paper, we summarize our recent research using alkali or alkaline earth metal amides, imides and hydrides for ammonia synthesis and decomposition. These materials could serve as either indispensible component of active center in thermal catalytic process or nitrogen carrier for chemical looping ammonia synthesis. The synergy of amide, imide, or hydride with transition metals enables ammonia synthesis or decomposition with unprecedented high efficiency under milder reaction conditions, and thus opens an avenue to advance the chemistry or catalysis of N₂ fixation reaction. The compositional and structural diversity of the amide, imide and hydride materials provides plenty of opportunity and potential for further exploration and optimization.     

Tetrabutylammonium bromide (TBAB): a neutral and efficient catalyst for the synthesis of biscoumarin and 3,4-dihydropyrano[c]chromene derivatives in water and solvent-free conditions

A simple, efficient and ecofriendly procedure has been developed using tetrabutylammonium bromide as catalyst for the synthesis of biscoumarin and dihydropyrano[c]chromene derivatives in water and solvent-free neat conditions. The present methodology offers several advantages such as excellent yields, short reaction time and environmentally benign milder reaction conditions.     

A highly flexible green synthesis of 1H-pyrazolo[1,2-b]phthalazine- 5,10-dione derivatives with CuI nanoparticles as catalyst under solvent-free conditions

CuI nanoparticles as an efficient catalyst have been used for the preparation of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones by the four-component condensation reaction of phthalic anhydride, hydrazine monohydrate, aromatic aldehydes and malononitrile or ethyl cyanoacetate under solventfree conditions in good to excellent yields, short reaction times and environmentally benign, milder reaction conditions.     

Theoretical and experimental studies of the all gas-phase iodine laser

All gas-phase iodine laser (AGIL) powered by the decomposition of nitrogen trichloride (NCl₃) is studied. This reaction scheme uses commonly available reagents and reaction paths are milder than the previously studied azide-based AGIL. Theoretical studies revealed the necessary operational conditions for achieving positive gain. An apparatus is made based on the results of the theoretical works. Positive gain at iodine I(² P _1/2)-I(² P _3/2) transition is observed for the first time. The article is published in the original.     

A convenient route to enantiomerically pure highly oxygenated decalins from sugar allyltin derivatives

Preparation of enantiomerically pure, highly oxygenated decalins via tandem Wittig-type Diels–Alder reactions from the corresponding sugar-derived dieno-phosphoranes and/or -phosphonates and sugar aldehydes is described. Application of the phosphonates is more convenient than phosphoranes since the former can be prepared in much higher yields and react with aldehydes under milder conditions. The intermediate trienes resulting from the Wittig-type process undergo spontaneous and highly stereoselective cyclization to the cis-decalins under the reaction conditions.     

Transition‐Metal‐Free Formal Sonogashira Coupling and α‐Carbonyl Arylation Reactions

Transition‐metal‐free formal Sonogashira coupling and α‐carbonyl arylation reactions have been developed. These transformations are based on the nucleophilic aromatic substitution (S_NAr) of β‐carbonyl sulfones to electron‐deficient aryl fluorides, producing a key intermediate that, depending on the reaction conditions, gives the aromatic alkynes or α‐aryl carbonyl compounds. The development of these reactions is presented and, based on investigations under basic and acidic conditions, mechanisms have been proposed. To develop the formal Sonogashira coupling further, a milder, two‐step protocol is also disclosed that expands the reaction concept. The scope of these reactions is demonstrated for the synthesis of Sonogashira and α‐carbonyl arylated products from a range of electron‐deficient aryl fluorides with a variety of functional groups and aryl‐, heteroaryl‐, alkyl‐, and alkoxy‐substituted sulfone nucleophiles. These transition‐metal‐free reactions complement the metal‐catalyzed versions in terms of substitution patterns, simplicity, and reaction conditions.     

Construction of the benzindenoazepine skeleton via cyclopentannulation of Fischer aminocarbene complexes: total synthesis of bulgaramine

A total synthesis of bulgaramine has been accomplished with a longest linear sequence of eight steps and an overall yield of 23% from commercially available 3,4-dimethoxyphenethyl alcohol. An intramolecular cyclopentannulation reaction of a Fischer aminocarbene complex provided the key step and occurred under significantly milder conditions and in higher yields than those of other reported examples of this reaction type. The reaction solvent was a critical factor in the cyclopentannulation reaction, with measurable amounts of the desired product observed only when THF was utilized. The product yield could be further enhanced by the addition of two-electron donor ligands, demonstrating the first example of this effect on the thermal reaction of aminocarbene complexes with alkynes.     

Transesterification of palm oil using supercritical methanol with co-solvent HCFC-141b

The transesterification of palm oil in supercritical methanol has been investigated without using any catalyst. HCFC-141b was used as co-solvent to reduce the molar ratio of methanol to palm oil under the milder conditions. The reaction was carried out in a flow-type tubular reactor. The residence time was fixed at 40 min. When the molar ratio of methanol to palm oil was set to 20:1 at 325 °C and 35 MPa, the optimum molar ratio of methanol to co-solvent was found to be 20:1. Addition of HCFC-141b increased FAME production even at the lower molar ratio of methanol to palm oil. In addition, a similar FAME content was obtained under the milder conditions (5 MPa lower pressure) compared with conditions without co-solvent at higher pressure. The role of HCFC-141b in the transesterification reaction under supercritical conditions was investigated.     

Synthesis of Polystyrene and Polystyrene/Poly(methyl methacrylate) Nanoparticles

Summary: Polystyrene nanosize particles have been synthesized by a differential microemulsion polymerization process involving the use of a small amount of poly(methyl methacrylate) as the seeds. Sodium dodecyl sulfate and ammonium persulfate were used as the surfactant and initiator, respectively. The effects of various reaction conditions on the particle size have been investigated. Particle sizes of less than 20 nm have been achieved at milder conditions than those previously reported in the literature.

An HRTEM image of PS/PMMA nanoparticles.