A NEW AND EFFICIENT SYNTHESIS OF INDENONE

Reaction of dichloroketone 2 with NEt₃ gave indenone (4) in high yield. Catodic reaction of 2 in the presence of C/Pt electrodes afforded the rearranged product 3 in high yield besides a small amount of chlorohydroxyketone 5. Reaction of rearranged dichloroketone 3 with NEt₃ provided indenone (4) as the sole product. The mechanism of these reaction was discussed.     

A MILD AND EFFICIENT CsOH-PROMOTED SYNTHESIS OF DITERTIARY PHOSPHINES

A mild and efficient method for the synthesis of ditertiary phosphines has been developed. In the presence of cesium hydroxide, molecular sieves, and DMF, various dihalides were coupled with diphenylphosphine at room temperature, and the results have demonstrated that this methodology offers a general synthetic procedure producing a variety of ditertiary phosphines in high yields.     

A NEW EFFICIENT SYNTHESIS OF TRIFLUOROACETYL HALIDES AND MIXED ANHYDRIDES OF PHOSPHORUS AND TRIFLUOROACETIC ACIDS

Abstract

Reaction of trifluoroacetic anhydride with chloroanhydrides of phosphorus acids R₂P(O)CI results in formation of mixed anhydrides R₂P(O) OCOCF₃ and trifluoroacetic acid halides CF₃COX (X=Cl, Br, I) in quantitative yield.     

A NOVEL AND EFFICIENT SYNTHESIS OF 3-ARYL AND 3-HETEROARYL SUBSTITUTED-1H-INDAZOLES AND THEIR MANNICH DERIVATIVES

ABSTRACT

A general and highly convenient procedure for the synthesis of 3-heteroaryl and 3-aryl substituted-1H-indazoles has been developed. These compounds (3a–f) were synthesized in good yield by refluxing the NaHSO₃ adduct of heteroaromatic and aromatic aldehyde and phenyl hydrazine in DMF. This procedure is more general and shorter than earlier methods. Five new 3-hetero-aryl substituted-1H-indazoles were synthesized and characterized. New Mannich derivatives of 3-(1H-pyrrol-2-yl)-1H-indazole (3a) and 3-(1H-indol-3-yl)-1H-indazole (3b) were prepared from morpholine and formaldehyde.     

HIGHLY EFFICIENT SYNTHESIS OF 2-AMINO-3-PYRIDINECARBOXALDEHYDE

2-Amino-3-pyridinecarboxaldehyde is synthesized in a highly efficient process via ortho-lithiation of 2-(pivaloylamino)pyridine and reaction with DMF, followed by acid hydrolysis. Major impurities were identified and were cleanly eliminated through careful choice of base and solvent.     

AN EFFICIENT ONE POT SYNTHESIS OF 1,3,4-OXADIAZOLES

Various 1,3,4-oxadiazoles have been synthesized in excellent yields by BF₃?Et₂O promoted cyclodehydration of 1,2-diacyl and diaroyl hydrazines prepared in situ from corresponding acid chlorides and hydrazine.     

EFFICIENT,MULTIGRAM-SCALE SYNTHESIS OF THREE 2,5-DIHALOBENZOQUINONES

ABSTRACT

2,5-Dibromo-, 2,5-dichloro- and 2,5-diiodobenzoquinone were conveniently prepared from 1,4-dimethoxybenzene in 87%, 97% and 84% overall yields. None of the two steps of the synthesis required purification.     

TRIPHENYPHOSPHINE-MEDIATED EFFICIENT SYNTHESIS OF FUNCTIONALIZED 2-OXO-2H-CHROMENES

Dimethyl acetylenedicarboxylate reacts smoothly with phenol derivatives, such as 4-chloro-3,5-dimethylphenol, 2-chloro-5-methylphenol, 4-chloro-2-methylphenol, 2,4-dichlorophenol, or 2-bromophenol in the presence of triphenylphosphine to produce highly functionalized 2-oxo-2 H-chromenes (coumarins) in moderate yields.     

LARGE SCALE,EFFICIENT SYNTHESIS OF 9-UNSUBSTITUTED DIPYRRINONE

ABSTRACT

9-Unsubstituted dipyrrinone 8, the useful precursor for the synthesis of biliverdins, bilirubins, and other bile pigments, was synthesized in large scale and high yield starting from acetaldehyde and nitroethane in eight steps with overall yield 10%. The key intermediate 3,4-dimethyl-2-ethoxycarbonylpyrrole 3 was synthesized via Zard–Barton's method in high yield.     

EFFICIENT SYNTHESIS OF POLYLACTOSAMINE STRUCTURES THROUGH REGIOSELECTIVE GLYCOSYLATIONS[1]

Di-, tri- and tetramers of β-(1→3)-linked N-acetyllactosamine residues have been synthesised as their methyl glycosides, to be used in ITC binding studies to various galectins. The synthetic strategy involves two types of regioselective glycosylations: couplings of a galactosyl donor to 3,4-diol N-tetrachlorophthalimido glucose acceptors to give the lactosamine monomer building blocks, and subsequent formation of the oligomers through consecutive couplings of lactosamine donors to 2′,3′,4′-lactosamine acceptors, with high selectivity for the desired products.     

AN EFFICIENT AND STRAIGHTFORWARD SYNTHESIS OF SIALYL Le X GLYCOLIPID AS A POTENT SELECTIN BLOCKER[[1]]

An efficient synthesis of sialyl Lewis X (sLe^x) glycolipid as a potent selectin blocker is described. 2-(Tetradecyl)hexadecanol which functions as an artificial ceramide, was glycosylated with phenyl 4-O-acetyl-6-O-benzyl-2-deoxy-3-O-(4-methoxybenzyl)-2-phthalimido-1-thio-β-d-glucopyranoside at the first step of the synthetic scheme. The N-acetylglucosamine acceptor carrying the hydrophobic aglycon was then coupled with sialyl-α-(2→3)galactose donor to afford the trisaccharide which upon successive α-l-fucosylation and deprotections, resulted in sLe^x glycolipid in quite straightforward steps.     

AN EFFICIENT SYNTHESIS OF 3,4-DIHYDRO-1H-2,3-BENZOTHIAZINE 2,2-DIOXIDES USING AMBERLYST 15 AND AMBERLYST XN 1010

ABSTRACT

Resins Amberlyst 15 and Amberlyst XN 1010 are used in the synthesis of 3,4-dihydro-1H-2,3-benzothiazines 2,2-dioxide. Advantages of this new procedure are simple work-up, high yield and selectivity, easy recovery of the catalyst and no waste problems.     

AN EFFICIENT ONE POT SYNTHESIS OF CARBAMATE ESTERS THROUGH ALCOHOLIC TOSYLATES*

ABSTRACT

An efficient O-alkylation of alcoholic tosylates with amines in a K₂CO₃/CO₂ system in the presence of tetrabutyl ammonium iodide (TBAI) provides exclusive formation of carbamates.

     

荧光素及四碘荧光素水溶液产氢的光化学研究

荧光素水溶液(浓度1×10^-4mol/L,pH 12.5)的荧光能为三乙醇胺(TEOA)所猝灭,其规律符合Stern-Volmer方程.荧光素的单重激发态的猝灭产物,荧光素的还原态,能够在氯铂酸钾(K₂PtCl₆)的存在下还原水产氢.但荧光寿命短(7.0ns),产氢的量子产率只有0.024.四碘荧光素由于有重原子效应,其单重激发态通过系间窜越转变成三重激发态,再和TEOA反应生成还原态去还原水产氢.由于磷光寿命长(～10^-3s),产氢的量子产率达0.30.     

AN EFFICIENT SYNTHESIS OF POLYMETHYLENE-BIS-AROYL THIOUREA DERIVATIVES UNDER THE CONDITION OF PHASE-TRANSFER CATALYSIS

Reaction of polymethylene diamine with aroyl chloride and ammonium thiocyanate under the condition of solid–liquid phase-transfer catalysis using polyethylene glycol-400 (PEG-400) as the catalyst yielded polymethylene-bis-aroyl thiourea derivatives 3a–q in good-to-excellent yield. The products have been characterized by analytical and spectral (IR and H¹ NMR) data.     

荧光素钠溶液的pH值对其激光及光谱特性的影响

本文研究了荧光素钠乙醇溶液的pH值对其激光能量转换效率以及吸收光谱、荧光光谱等特性的影响。通过对其吸收光谱的研究, 证明荧光素钠在乙醇溶液中存在多种互变异构体。在不同pH值的溶液中, 它们具有不同的浓度而处于酸碱平衡。各种异构体对λ=337.1 nm激发光的吸收截面σ_P和其荧光最子产额φ各不相同。随着pH值的增大, 溶液中双价阴离子的浓度逐渐增大。而双价阴离子的σ_P和φ值为最大。由于激光输出能量的大小与σ_P和φ直接有关, 因此, 荧光素钠溶液的激光能量转换效率也将随着pH值的增大而提高。     

荧光素掺杂的TiO2凝胶的制备及光谱研究

近些年来,溶胶－凝胶（Ｓｏｌ－Ｇｅｌ）方法作为一种软化学合成方法具有很多优点［１］,例如制作简单、烧结温度低,制得样品稳定、坚韧,制备灵活性高等。作为一种常用的染料,荧光素（ＦＬ）常用于研究非线性光学。利用Ｓｏｌ－Ｇｅｌ法可以很好地将染料分子固定在光...     

荧光素在明胶片中的光吸收及稳定性

由于对非线性光学材料的需求,近年来已有很多工作对荧光素的光学及光化学性质进行研究,研究对象既有溶液也有聚合物薄膜。本工作使用明胶片研究荧光素在明胶片中的光吸收、荧光及光稳定性。     

AN EXCEEDINGLY MILD AND EFFICIENT SYNTHESIS OF 1,2,4-TRIAZOLO[4,3-a][1,8]NAPHTHYRIDINES USING IODOBENZENE DIACETATE IN THE SOLID STATE

ABSTRACT

An efficient and mild method for the synthesis of 1,2,4-triazolo[4,3-a][1,8]naphthyridines using iodobenzene diacetate (IBD) in the solid state at room temperature has been described. The reaction proceeds efficiently at room temperature in good yields and in a solid of high purity.